Leishmaniasis

Leishmaniasis is a disease caused by an intracellular protozoa parasite transmitted by the bite of a female sandfly (Phlebotomus species). The clinical spectrum of leishmaniasis ranges from a self-resolving, localized cutaneous ulcer to widely disseminated progressive lesions of the skin, to a mutilating mucocutaneous disease, and even to a lethal systemic illness that affects the reticuloendothelial system.

Classic Leishmania major lesion from a case in Iraq shows a volcanic appearance with rolled edges.

The predominant mode of leishmaniasis transmission is a sandfly's bite.

Leishmania donovani is one of the main Leishmania species that infects humans.

This condition affects as many as 12 million people worldwide, with 900,000 to 1.3 million new cases each year. The global incidence of leishmaniasis has increased in recent years due to increased international leisure- and military-related travel, human alteration of vector habitats, and concomitant factors that increase susceptibility, such as infection with human immunodeficiency virus (HIV) and malnutrition. With the exception of Australia, the Pacific Islands, and Antarctica, the parasites have been identified throughout large portions of the world.

Old World localized cutaneous leishmaniasis located on the trunk of a soldier stationed in Kuwait. This lesion was a 3-cm by 4-cm nontender ulceration that developed over the course of 6 months at the site of a sandfly bite. The patient reported seeing several rats around his encampment.

Old World cutaneous leishmaniasis located on the right arm of the same soldier stationed in Kuwait. This 2-cm by 3-cm lesion was located at the exposed area where the sleeve ended. Note the satellite lesions.

The taxonomy of Leishmania organisms is complex, and no single categorization is generally accepted.

Taxonomy of some of the medically important protozoans showing the relative relationship of the Kinetoplastida parasites generally, and Leishmania specifically.

The 2 simplest and most widely used disease categorization systems are based on clinical disease and geographic occurrence, as follows:

• Clinical disease: The primary clinical forms of leishmaniasis are cutaneous, mucocutaneous, and visceral disease; cutaneous manifestations can be further subdivided into localized, diffuse (disseminated), recidivans, and post–kala-azar dermal leishmaniasis

• Geographic occurrence: Old World leishmaniasis is caused by Leishmania species found in Africa, Asia, the Middle East, the Mediterranean, and India, and it produces cutaneous or visceral disease; New World leishmaniasis is caused by Leishmania species found in Central America and South America, and it produces cutaneous, mucocutaneous, and visceral disease. Diagnosis of leishmaniasis often is difficult because of the small size of the protozoa sequestered within macrophages of the skin, bone marrow, and reticuloendothelial system.

Therapy has long been a challenge in the more severe forms of the disease, and it is made more difficult by the emergence of drug resistance. No effective vaccine for leishmaniasis is available.

Modes of transmission

In leishmaniasis, the obligatory intracellular protozoa are transmitted to mammals via the bite of the tiny 2- to 3-mm female sandfly of the genus Phlebotomus in the Old World (Eastern Hemisphere) and Lutzomyia in the New World (Western Hemisphere).

Sandfly. Courtesy of Kenneth F. Wagner, MD.

The bite of 1 infected sandfly is sufficient to cause the disease, because a sandfly can egest more than 1000 parasites per bite. Traditionally divided between Old World and New World parasites, more than 20 pathogenic species of Leishmania have been identified[1] ; about 30 of the 500 known phlebotomine sandfly species have been positively identified as vectors of the disease.[2]

The sandfly usually is one half to one third the size of a mosquito (see the image below). Leishmaniasis infections are considered zoonotic diseases, because for most species of Leishmania, an animal reservoir is required for endemic conditions to persist. Humans are generally considered incidental hosts. Infections in wild animals are usually not pathogenic, with the exception of dogs, which may be severely affected.

Comparison of a sandfly (left) and a mosquito (right). The sandfly's small size affects the efficacy of bed nets when used without permethrin treatment.

Common Old World hosts are domestic and feral dogs, rodents, foxes, jackals, wolves, raccoon-dogs, and hyraxes. Common New World hosts include sloths, anteaters, opossums, and rodents. The reservoir of infection for Indian kala-azar is humans, whereas it is rodents for African kala-azar, foxes in Brazil and Central Asia, and canines for the Mediterranean and Chinese kala-azar. Other mammalian reservoirs for the Leishmania parasite include equines and monkeys.

Uncommon modes of transmission include congenital transmission, contaminated needle sticks, blood transfusion, sexual intercourse, and, rarely, inoculation of cultures. Although clear documentation of the potential of transfusion-associated leishmaniasis exists, there is less certainty of clear documentation of the actual occurrence of transfusion-related disease, because most cases in the literature occur in endemic areas of the world.[3, 4]

In India, visceral leishmaniasis caused by L donovani does not appear to have an animal reservoir and is thought to be transmitted via human-sandfly-human interaction.

Coinfection with human immunodeficiency virus (HIV) has led to the spread of leishmaniasis, typically a rural disease, into urban areas. In patients infected with HIV, leishmaniasis accelerates the onset of acquired immunodeficiency syndrome (AIDS) by cumulative immunosuppression and by stimulating the replication of the virus. It may also change asymptomatic Leishmania infections into symptomatic infections. Sharing of needles by intravenous drug users can spread not only HIV but also leishmaniasis.

Leishmania life cycle

The parasites exist in the flagellated promastigote stage in sandflies and in artificial culture and then transform into the nonflagellated amastigote form in animal and human hosts.

Life cycles of the medically important Kinetoplastida illustrating the similarities and differences between the trypanosomes and Leishmania.

Only the female sandfly transmits the protozoan, infecting itself with the Leishmania parasites contained in the blood it sucks from its human or mammalian host. Over 4-25 days, the parasite continues its development inside the sandfly, where it undergoes a major transformation into the promastigote form. A large number of flagellate forms (promastigotes) are produced by binary fission. Multiplication proceeds in the mid gut of the sandfly, and the flagellates tend to migrate to the pharynx and buccal cavity of the sandfly. A heavy pharyngeal infection is observed between Days 6 and 9 of an infected blood meal. The promastigotes are regurgitated via a bite during this period, resulting in the spread of leishmaniasis.

Following the bite, some of the flagellates that enter the new host’s circulation are destroyed, whereas others enter the intracellular lysosomal organelles of macrophages of the reticuloendothelial system, where they lose their flagella and change into the amastigote form (see the first image below). The amastigote forms also multiply by binary fission, with multiplication continuing until the host cell is packed with the parasites and ruptures, liberating the amastigotes into the circulation (see the second image below). The free amastigotes then invade fresh cells, thus repeating the cycle and, in the process, infecting the entire reticuloendothelial system. Some of the free amastigotes are drawn by the sandfly during its blood meal, thus completing the cycle.

Post–kala-azar dermal leishmaniasis. Courtesy of R. E. Kuntz and R. H. Watten, Naval Medical Research Unit, Taipei, Taiwan.

Mucocutaneous leishmaniasis. Courtesy of Kenneth F. Wagner, MD.

Depending on the species of parasite and the host’s immune status, the parasites may incubate for weeks to months before presenting as skin lesions or as a disseminated systemic infection involving the liver, spleen, and bone marrow. Temperature is an important factor that helps determine the localization of leishmanial lesions. Species causing visceral leishmaniasis are able to grow at core temperatures, whereas those responsible for cutaneous leishmaniasis grow best at lower temperatures. Pathogenesis appears related to T-cell cytotoxicity.

Cutaneous leishmaniasis is caused by L tropica; an animal reservoir for leishmaniasis caused by this organism has not been identified, although it has been found in some dogs in endemic areas. Morphologically, it is indistinguishable from L donovani. The life cycle is exactly the same as that of L donovani except that the amastigote form resides in the large mononuclear cells of the skin.

Pathogenesis

After inoculation by sandflies, the flagellated promastigotes bind to macrophages in the skin. Two of the parasite surface molecules appear to play a prominent role in parasite-phagocyte interactions. The extent and presentation of disease depend on several factors, including the humoral and cell-mediated immune response of the host, the virulence of the infecting species, and the parasite burden. Infections may heal spontaneously or may progress to chronic disease, often resulting in death from secondary infection.

Promastigotes activate complement through the alternate pathway and are opsonized. The most important immunologic feature is a marked suppression of the cell-mediated immunity to leishmanial antigens. In persons with asymptomatic self-resolving infection, T-helper (Th1) cells predominate, with interleukin 2 (IL-2), interferon-gamma, and IL-12 as the prominent cytokines that induce disease resolution, although immune suppression years later can result in disease. An overproduction of both specific immunoglobulins and nonspecific immunoglobulins also occurs. The increase in gamma globulin leads to a reversal of the albumin-globulin ratio commonly associated with this disease.

As noted earlier, leishmaniasis involves the reticuloendothelial system. Parasitized macrophages disseminate infection to all parts of the body but more so to the spleen, liver, and bone marrow. The spleen is enlarged, with a thickening of the capsule, and is soft and fragile; its vascular spaces are dilated and engorged with blood. The reticular cells of Billroth are markedly increased and packed with the amastigote forms of the parasite. However, no evidence of fibrosis is present. In the liver, the Kupffer cells are increased in size and number and infected with amastigote forms of Leishmania. Bone marrow turns hyperplastic, and parasitized macrophages replace the normal hemopoietic tissue.

With visceral or diffuse (disseminated) cutaneous disease, patients exhibit relative anergy to the Leishmania organism and have a prominent Th2 cytokine profile. Typically, visceral leishmaniasis incubates for weeks to months before becoming clinically apparent. The disease can be subacute, acute, or chronic, and can manifest in patients who are immunocompromised years after they have left endemic regions.

In addition, susceptibility genes in band 22q12 have been found in an ethnic group in parts of Sudan that has a high prevalence rate of visceral leishmaniasis.

Risk factors

Poverty and malnutrition play a major role in the increased susceptibility to leishmaniasis. Extracting timber, mining, building dams, widening areas under cultivation, creating new irrigation schemes, expanding road construction in primary forests such as the Amazon, continuing widespread migration from rural to urban areas, and continuing fast urbanization worldwide are among the primary causes for increased exposure to the sandfly. 

Distribution map of cutaneous leishmaniasis.

Geographical distribution of visceral leishmaniasis in the Old and New world. Source: World Health Organization, Department of Control of Neglected Tropical Diseases, Innovative and Intensified Disease Management (WHO/NTD/IDM) Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS), Tuberculosis and Malaria (HTM) WHO, October 2010: http://www.who.int/leishmaniasis/leishmaniasis_maps/en/.

Another risk factor is the movement of susceptible populations into endemic areas, including large-scale migration of populations for economic reasons. In the city of Kabul, Afghanistan, which has a population of less than 2 million, an estimated 270,000 cases of cutaneous leishmaniasis occurred in 1996. The resurgence of visceral leishmaniasis has occurred because of deficiencies in the control of the vector (sandfly), absence of a vaccine, and lack of access to medical treatment due to cost and increasing drug resistance to first-line treatment.

Coexistence of leishmaniasis with human immunodeficiency virus (HIV) infection is a serious concern. Leishmaniasis is spreading in several areas of the world because of the rapid dissemination of the acquired immunodeficiency syndrome (AIDS) epidemic. The immune deficiency has led to increased susceptibility to infections, including leishmaniasis: Persons with AIDS are at 100-1000 times greater risk of developing visceral leishmaniasis in certain areas. Thus far, co-infections have been reported in 33 countries worldwide.

Distribution map of human immunodeficiency virus (HIV) and leishmaniasis coinfection.

Children are at greater risk than adults in endemic areas. Incomplete therapy of the initial disease is a risk factor for recurrence.

Commonly associated parasite species and their geographic distribution are summarized below.

Distribution of cutaneous leishmaniasis

Old World spread of localized cutaneous disease includes the following Leishmania species:

• L donovani - China, India, Bangladesh, Sudan

• L tropica - Middle East, China, India, Mediterranean

• L aethiopica - Ethiopia, Kenya, Namibia

• L major - Middle East, Africa, India, Asia

• L infantum - Asia, Africa, Europe

Old World spread of diffuse cutaneous leishmaniasis is via L aethiopica in Ethiopia, Kenya, and Namibia.

Geographical distribution of Old World cutaneous leishmaniasis due to L tropica and related species and L aethiopica. Source: World Health Organization, Department of Control of Neglected Tropical Diseases, Innovative and Intensified Disease Management (WHO/NTD/IDM) Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS), Tuberculosis and Malaria (HTM) WHO, October 2010: http://www.who.int/leishmaniasis/leishmaniasis_maps/en/index1.html

Geographical distribution of Old World cutaneous leishmaniasis due to L major. Source: World Health Organization, Department of Control of Neglected Tropical Diseases, Innovative and Intensified Disease Management (WHO/NTD/IDM) Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS), Tuberculosis and Malaria (HTM) WHO, October 2010: http://www.who.int/leishmaniasis/leishmaniasis_maps/en/index1.html.

New World spread of localized cutaneous disease includes the following Leishmania species:

• L mexicana - Central, South, and North America

• L amazonensis - Dominican Republic, Central and South America

• L venezuelensis - Venezuela

• L (Viannia) braziliensis - Central and South America

• L (Viannia) guyanensis - Guyana, French Guyana, Surinam, Brazil

• L (Viannia) panamensis - Costa Rica, Panama, Colombia, Ecuador

• L (Viannia) peruviana - Peru, Argentina

• L donovani chagasi - Texas, Caribbean, Central and South America

New World spread of diffuse cutaneous leishmaniasis is via (1) L mexicana in Central, South, and North America, (2) L amazonensis in the Dominican Republic and Central and South America, and (3) L venezuelensis in Venezuela.

Leishmaniasis recidivans

A relatively uncommon clinical variant of leishmaniasis, leishmaniasis recidivans appears as a recurrence of lesions at the site of apparently healed disease years after the original infection.

Old World spread of leishmaniasis recidivans is via L tropica in the Middle East, China, India, and the Mediterranean. New World spread of leishmaniasis recidivans is via L (Viannia) braziliensis in Central and South America.

Post–kala-azar leishmaniasis

The term kala-azar—which means black (kala) fever (azar) in Hindi—is reserved for severe (advanced) cases of visceral leishmaniasis, although the terms kala-azar and visceral leishmaniasis sometimes are used interchangeably.[2]

Post–kala-azar dermal leishmaniasis (PKDL) is a syndrome characterized by skin lesions that develop at variable intervals after (or during) therapy for visceral leishmaniasis.[2] This condition is best described in cases of L donovani infection in South Asia and East Africa. In general, post–kala-azar dermal leishmaniasis is more common, develops earlier, and is less chronic in patients in East Africa.[2]

Old World spread of post–kala–azar leishmaniasis is via the following:

• L donovani - China, India, and Bangladesh

• L infantum - Asia, Africa, and Europe

• New World spread of post–kala–azar leishmaniasis is via L donovani chagasi in Central and South America.

Distribution of mucocutaneous leishmaniasis

Old World spread of mucocutaneous leishmaniasis is via L aethiopica in Ethiopia, Kenya, and Namibia.

New World spread of mucocutaneous leishmaniasis includes the following Leishmania species:

• L (Viannia) braziliensis - Central and South America

• L (Viannia) panamensis - Central and South America

• L (Viannia) guyanensis - Guyana, French Guyana, Surinam, and Brazil

• Less often seen with L mexicana - Central, South, and North America

• Less often seen with L amazonensis - Brazil and Panama

  Geographical distribution of cutaneous and mucocutaneous leishmaniasis in the New World. Source: World Health Organization, Department of Control of Neglected Tropical Diseases, Innovative and Intensified Disease Management (WHO/NTD/IDM) Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS), Tuberculosis and Malaria (HTM) WHO, October 2010: http://www.who.int/leishmaniasis/leishmaniasis_maps/en/

Distribution of visceral leishmaniasis

Old World spread of visceral leishmaniasis is via the following:

• L donovani - China, India, Bangladesh, Sudan, and Kenya

• L infantum - Asia, North Africa, and South Europe

• (Rarely) L tropica - Iran and Kenya

New World spread of visceral leishmaniasis is via L donovani chagasi in Central and South America.

Distribution map of visceral leishmaniasis.

Distribution of viscerotropic leishmaniasis

Old World spread of viscerotropic leishmaniasis is via L tropica in the Middle East.

United States statistics

Endemic leishmaniasis is uncommon in the United States. Although sandflies are found as far north as upstate New York, and visceral leishmaniasis has been identified in foxhounds in a wide geographic distribution in the United States, virtually no human transmission is believed to occur in the majority of the United States.

Periodic, isolated cases of localized and diffuse cutaneous leishmaniasis have been reported in areas bordering Mexico, such as southern Texas, Oklahoma,[5, 6] and Pennsylvania, with no associated travel outside the patient’s home. The usual reservoir is the wood rat of the Southern Plains, but parasites have been identified in coyotes and domesticated dogs and cats. Spread by the sandfly vector Lutzomyia anthophora, leishmaniasis cases are usually associated with exposure to the habitat of the wood rat.

There were 2 cases of L mexicana cutaneous leishmaniasis described at the end of 2009 and none after that year. Per the WHO Global Health Observatory Data Repository, no new cases of visceral leishmaniasis have been reported since 2005.

Most of the cases of leishmaniasis found in the United States are acquired elsewhere: US travelers, government workers, graduate students, Peace Corps workers, and military personnel are at risk overseas. Between 1985 and 1990, the Centers for Disease Control and Prevention (CDC) was notified of 129 cases involving travelers from the United States who acquired the disease abroad.

During World War II, more than 1000 cases of cutaneous leishmaniasis were reported among US service members serving in the Persian Gulf. Illnesses now attributed to leishmaniasis have been identified throughout military campaigns from World War I back to antiquity.

During the first Persian Gulf War, an estimated 400 cases of cutaneous leishmaniasis and 12 cases of viscerotropic leishmaniasis were reported.[7] The etiologic agent for most of the cutaneous leishmaniasis cases appears to have been L major. Since 2001, more than 700 US military personnel have been diagnosed with cutaneous leishmaniasis and 4 with visceral leishmaniasis after serving in Afghanistan and the Middle East.

The conflicts in Iraq and Afghanistan led to approximately 2000 laboratory-confirmed cases (and at least double the number of unconfirmed cases) of cutaneous leishmaniasis and 5 laboratory-confirmed cases of visceral leishmaniasis in American soldiers alone from 2003-2008.[8, 9] More than 500 cases of leishmaniasis were diagnosed over an 18-month period in soldiers returning to the United States from the Middle East, especially from Iraq. A large portion of these was identified as cutaneous leishmaniasis. Up to 1% of US forces serving in the Southwest Asian Theater may have been infected.[10]

International statistics

Geographic distribution of leishmaniasis is generally restricted to tropical and temperate regions (natural habitats of the sandfly), and it is limited by the sandfly’s susceptibility to cold climates, its tendency to take blood from humans or animals only, and its capacity to support the internal development of specific species of Leishmania. With the increase in international travel, immigration, overseas military exercises, and coinfection with human immunodeficiency virus (HIV), leishmaniasis is becoming more prevalent throughout the world.

The World Health Organization (WHO) reports endemic leishmaniasis in 98 countries and 3 territories on 5 continents (Africa, Asia, Europe, North America, South America), with an official estimated annual incidence of 0.7-1.3 million cases of cutaneous disease and 0.2-0.4 million cases of visceral disease.[11]

Approximately 95% of cases of cutaneous disease occur in the Americas, the Mediterranean Basin, the Middle East, and Central Asia. More than two thirds of these cases are reported in 6 countries, including Afghanistan, Algeria, Brazil, Colombia, Iran, and Syria. Over 90% of new cases of visceral leishmaniasis occur in 6 countries: Bangladesh, Brazil, Ethiopia, India, South Sudan, and Sudan.[11] India has the largest burden of visceral leishmaniasis, with 13,869 new cases reported in 2013.[12]

The visceral leishmaniasis control program has achieved significant gains in Southeast Asia, with the incidence declining to 10,209 cases in 2014, which is approximately 75% lower than in 2005, when the Kala-Azar control program was launched. In this region, the disease is on the verge of being removed from the Public Health Problem list.[13]

Almost 90% of mucocutaneous leishmaniasis cases occur in Bolivia, Brazil, and Peru.[11]

In Colombia, the military fighting the Fuerzas Armadas Revolucionarias de Colombia (FARC) saw more than 30,000 cases of leishmaniasis over 3-year period.

Countries and/or regions not considered to have endemic leishmaniasis despite being surrounded by regions that do include Australia and the South Pacific, Chile, Uruguay, and Canada.

Visceral and cutaneous leishmaniasis in patients with AIDS have been increasingly appreciated as a potential opportunistic infection. Coinfection with HIV has been reported in more than 35 countries throughout southern Europe, the Mediterranean Basin, Central and South America, and India.[14] Disease occurs in conjunction with severe immunosuppression. The incidence of coinfection has decreased in developed countries because of the widespread use of antiretroviral therapy.

Racial, sexual, and age-related differences in incidence

Although no racial preferences are recognized or described for leishmaniasis, some minor associations with various racial groups have been noted. However, but those data are confounded by and result more strongly in association with occupational exposure

Males have an increased incidence of infection, about double that of females. The higher rates of infection in men, particularly visceral leishmaniasis, may be from increased environmental exposure to the habitat of the sandfly through occupation and leisure activity.

Leishmaniasis affects various age groups, depending on the infecting species, geographic location, disease reservoir, and host immunocompetence. Individuals at the extremes of age may be less able to mount effective immune responses to infection and therefore manifest clinical disease more often, especially seen in association with visceral leishmaniasis.

Cutaneous leishmaniasis affects all age groups. Reports from Afghanistan and Colombia show that adolescents and young adults are at risk the most. In Iran, most cases of the disease are found in infants.

Visceral leishmaniasis is found in all age groups in India and Brazil, where an animal reservoir has not been identified. In areas with known animal reservoirs, such as the Mediterranean Basin, visceral leishmaniasis mainly affects children, with devastating outcomes (eg, L infantum primarily affects children aged 1-4 y). This apparent predilection for the young appears to occur in highly endemic areas because of what may be protective immunity reducing the risk for reinfection in adults. Untreated visceral leishmaniasis in a pregnant individual can also have consequences on the fetus or result in congenital visceral leishmaniasis.

Generally, the prognosis depends on the nutritional and overall immune status of the host, the precise species of infection, as well as appropriate therapy.

Cutaneous leishmaniasis

Localized cutaneous leishmaniasis often spontaneously resolves in 3-6 months without therapy, although some infections persist indefinitely. Most individuals respond exceedingly well to therapy: Rapid, complete resolution of the lesion(s), with decreased potential for secondary bacterial infections and diminished scarring, is the rule. This is not to say that the disease is without morbidity, especially in areas where even minimal facial disfiguring can condemn young girls to life without the prospect of marriage or acceptance in society.

Most cases of diffuse cutaneous leishmaniasis, post–kala-azar dermal leishmaniasis, and leishmaniasis recidivans are chronic and resistant to treatment. These forms can be exceedingly disfiguring cosmetically because of the degree of persistent involvement; however, they are associated with low mortality rates.

Mucocutaneous leishmaniasis

Mucocutaneous leishmaniasis is chronic and progressive. This form of the disease affects the mucous membranes of the mouth, nose, and soft palate, and it is especially debilitating and destructive, resulting in extensive midfacial mutilation. Death can occur from secondary infection and after respiratory tract mucosal invasion. Respiratory compromise and dysphagia may lead to malnutrition and pneumonia.

The general consensus is that less than 5% of individuals infected by L brasiliensis, and a smaller percentage of individuals infected by L panamensis and L guyanensis, develop mucosal metastases several months to years after the apparent resolution of cutaneous disease. However, no rigorous studies prove this commonly accepted rate.

Visceral leishmaniasis

Visceral leishmaniasis is a serious, progressive, and potentially lethal systemic disease. It tends to affect individuals in poor states of health, with poor nutritional status, and with even the most minor decreased immune status much more severely than individuals with good health, good nutritional status, and intact immune systems.

In well-nourished individuals with intact immune systems, full recovery from visceral disease is expected after treatment with the appropriate medication. With early therapy and supportive care, mortality in patients with visceral disease is reduced to approximately 5%; without therapy, most patients with visceral disease (kala-azar) (75-95%) die within 2 years, often from malnutrition and secondary infection, such as bacterial pneumonia, septicemia, dysentery, tuberculosis, cancrum oris, and uncontrolled hemorrhage or its sequelae.

In some endemic regions, pentavalent antimonial resistance is causing increased mortality rates.

Complications

Complications of leishmaniasis occur as a consequence of anemia, leukopenia, and thrombocytopenia. They may include the following:

• Secondary bacterial infection, including pneumonia and tuberculosis

• Septicemia

• Disfigurement of nose, lips, and palate (eg, cancrum oris)

• Uncontrolled bleeding

• Splenic rupture

• Late stages: Edema, cachexia, and hyperpigmentation

• Metastatic lesions in the nasopharynx with tissue destruction

Coinfection with human immunodeficiency virus (HIV) can complicate cases of visceral leishmaniasis. A well-described and feared interaction is kala-azar in combination with HIV infection, which leads to more severe and rapidly progressive fatal outcomes from both diseases acting synergistically.

Behavior modification to avoid vector contact, combined with insect control measures, significantly diminishes the risk of acquiring infection.

Educate patients about (1) the possibility of recurrent disease, and instruct them to schedule follow-ups as needed; (2) the transmission of leishmaniasis; and (3) the risk factors of leishmaniasis, including the following:

• Exposure to sandfly habitat

• Age (depending on the infecting species and geographic area)

• Male sex

• Adults who are immunologically naïve and entering an endemic area

• Patients who are immunosuppressed (eg, transplant recipients, chronic steroid users, those with malignancies)

• Malnutrition

• Human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS)

• Intravenous drug use in endemic areas

Although the Leishmania species differ clinically and biologically, their characteristics overlap and each clinical syndrome can be produced by multiple species of Leishmania.

Cutaneous leishmaniasis

The broad spectrum of clinical manifestations of cutaneous leishmaniasis often is compared with that of leprosy. Cutaneous leishmaniasis can be simple or diffuse (disseminated). Different species, as well as host factors, can also affect the clinical picture, in which some species cause "wet" ulcers and others "dry" ulcers.

The hallmark of cutaneous leishmaniasis is skin lesions, which can spontaneously heal in 2-10 months. Inoculation occurs after a sandfly bites an exposed part of the body (usually the legs, arms, neck, or face). Incubation occurs over weeks to months, followed by the appearance of an erythematous papule, which can evolve into a plaque or ulcer. These lesions usually are painless.

No systemic symptoms are evident. After recovery or successful treatment, cutaneous leishmaniasis induces immunity to reinfection by the species of Leishmania that caused the disease.

Localized cutaneous disease

Both New World and Old World species cause localized cutaneous leishmaniasis. New World disease usually presents with a solitary nodule, whereas Old World disease is associated with multiple lesions. Systemic symptoms are absent. Wound progression occurs over time and may exhibit localized lymphangitic spread. 

Old World localized cutaneous leishmaniasis located on the trunk of a soldier stationed in Kuwait. This lesion was a 3-cm by 4-cm nontender ulceration that developed over the course of 6 months at the site of a sandfly bite. The patient reported seeing several rats around his encampment.

Old World cutaneous leishmaniasis located on the right arm of the same soldier stationed in Kuwait. This 2-cm by 3-cm lesion was located at the exposed area where the sleeve ended. Note the satellite lesions.

The lesions usually are without pain or pruritus, although secondary bacterial infection may complicate the wound (see the following image). Healing may occur spontaneously over 2-12 months and is followed by scarring and changes in pigmentation. New World disease may progress to mucocutaneous leishmaniasis.

Active cutaneous leishmaniasis lesion with likely secondary infection in a soldier.

Diffuse cutaneous leishmaniasis

Diffuse cutaneous disease develops in an anergic host with poor immune response. This condition is associated with a deficient cell-mediated immunity that enables the parasite to disseminate in the subcutaneous tissues and has been reported in patients with human immunodeficiency virus (HIV) infection.

Infection is characterized by a primary lesion, which slowly spreads to involve multiple areas of the skin (face, ears, extremities, buttocks) until the whole body is affected. Plaques, ulcers, and nodules may form over the entire body, resembling lepromatous leprosy (see the image below). However, no neurologic or systemic invasion is involved; as a result, although the lesions are neither destructive nor erosive, they are disfiguring. The infections are chronic and may recur after treatment.

Although diffuse disease is more common with New World species in Central and South America, Old World L aethiopica may progress to diffuse disease in East Africa.

Diffuse (disseminated) cutaneous leishmaniasis. Courtesy of Jacinto Convit, National Institute of Dermatology in Caracas, Venezuela.

Leishmaniasis recidivans

Leishmaniasis recidivans may occur years after a localized cutaneous lesion has healed, commonly presenting on the face (see the following image). New ulcers and papules form over the edge of the old scar and proceed inward to form a psoriasiform lesion. Infection may be from reactivation of dormant parasites or new infection from a different species. Skin trauma can result in activation of seemingly latent cutaneous infection long after the initial bite. The infections tend to be resistant to treatment.

Leishmaniasis recidivans. Courtesy of Kenneth F. Wagner, MD.

Post-kala-azar dermal leishmaniasis

Post-kala-azar dermal leishmaniasis follows the treatment of visceral leishmaniasis and has predominantly been described in Africa (about 2% of cases) and India (about 10% of cases).

The Indian variant occurs in patients 1-2 years and as long as 20 years after recovery from visceral leishmaniasis. This condition is characterized by multiple, hypopigmented, erythematous macules. Over time, these macules can transform into large nontender plaques and nodules that involve the face and trunk (see the image below). The disease resembles lepromatous leprosy and requires intensive therapy. The African variant occurs shortly after treatment of visceral leishmaniasis and is characterized by an erythematous papular rash on the face, buttocks, and extremities. These lesions spontaneously resolve over the course of several months.

Post–kala-azar dermal leishmaniasis. Courtesy of R. E. Kuntz and R. H. Watten, Naval Medical Research Unit, Taipei, Taiwan.

In Sudan, patients often present with a facial rash consisting of small papules resembling measles that spreads to involve other parts of the body. This syndrome may heal spontaneously, but relapse is common. Established disease is generally difficult to treat.

Post–kala-azar dermal leishmaniasis that is resistant to antimonial agents has been reported, with an incidence rate of 1 in 700 cases.

Mucocutaneous leishmaniasis

Mucocutaneous disease, also called espundia in South America, usually develops by metastasis from disseminated protozoa rather than by local spread. This condition is most commonly caused by New World species, although Old World L aethiopica has also been reported to cause this syndrome. Secondary infection plays a prominent role in the size and persistence of ulcers.

Infection by L (Viannia) braziliensis may lead to mucosal involvement in up to 10% of infections, depending on the region in which it was acquired. The incubation period is from 1 to 3 months. The initial infection is characterized by a persistent cutaneous lesion that eventually heals, although as many as 30% of patients report no prior evidence of leishmaniasis.

Ulcer progression is slow and steady. Several years later, oral and respiratory mucosal involvement occurs, causing inflammation and mutilation of the nose, mouth, oropharynx, and trachea (see the following image), resulting in symptoms of nasal obstruction and bleeding. These can become sites of infection, sometimes leading to sepsis. Cases in which the time between the primary lesion and the appearance of mucosal involvement is up to 2 decades have been reported.

Mucocutaneous leishmaniasis. Courtesy of Kenneth F. Wagner, MD.

Progressive mucocutaneous disease is difficult to treat and often recurs. With prolonged infection, death occurs from respiratory compromise and malnutrition. Mucocutaneous leishmaniasis may arise after inadequate treatment of certain Leishmania species.

Children rarely are affected.

Visceral leishmaniasis

Visceral disease, the most devastating and fatal form of leishmaniasis, is classically known as kala-azar or the Indian name for “black fever/disease,” which is a reference to the characteristic darkening of the skin that is seen in patients with this condition. Other terms used to describe visceral disease include Dumdum fever, Assam fever, and infantile splenomegaly in various parts of the world.

This condition occurs with both New and Old World species and results from systemic infection of the liver, spleen, and bone marrow. The spectrum of illness ranges from asymptomatic infection or self-resolving disease to fulminant, severe, life-threatening infection; many subclinical cases occur and go unrecognized for each clinically recognized case.

The syndrome is characterized by the pentad of fever, weight loss, hepatosplenomegaly, pancytopenia, and hypergammaglobulinemia. The fever is continuous or remittent and becomes intermittent at a later stage. It is also characteristically described as a double rise in 24 hours, in which waves of pyrexia may be followed by a period without fever. Patients may also report night sweats, weakness, diarrhea, malaise, and anorexia. Melanocyte stimulation and xerosis can occur, causing characteristic skin hyperpigmentation.

Onset of visceral disease can be insidious or sudden. The incubation period varies after infection (usually 3-6 mo, but can be months or years) and may depend on the patient's age and immune status as well as the species of Leishmania. Young malnourished children are most susceptible to developing progressive infection; those who present later in the course of the disease may present with edema caused by hypoalbuminemia, hemorrhage caused by thrombocytopenia, or growth failure caused by features of chronic infection.

If visceral disease is left untreated, death frequently occurs within 2 years which may be due to hemorrhage (secondary to infiltration of the hematopoietic system), severe anemia, immunosuppression, and/or secondary infections.

A variant of visceral leishmaniasis has been described in US soldiers who participated in the Gulf War. This is associated with light parasitic burden and mild symptoms including fever, malaise, and nausea.

Viscerotropic leishmaniasis

Viscerotropic leishmaniasis has an indolent but distinct clinical presentation and does not appear to progress to full visceral leishmaniasis. Patients have presented with an array of symptoms months to years after infection, including fever, rigors, fatigue, malaise, nonproductive cough, intermittent diarrhea, headache, arthralgias, myalgias, nausea, adenopathy, transient hepatosplenomegaly, and abdominal pain.

Although L tropica traditionally has been associated with cutaneous leishmaniasis, several reports of visceral disease have been reported from Kenya, India, and Israel. In addition, reports of patients returning from the Middle East showed presentations ranged from 1 month to 2 years after exposure, with many of symptoms described above: malaise, fatigue, intermittent fever, cough, diarrhea, abdominal pain, and other gastrointestinal symptoms.

Cutaneous leishmaniasis

Cutaneous disease may have the following physical manifestations:

• Localized cutaneous leishmaniasis: Crusted papules or ulcers on exposed skin; lesions may be associated with sporotrichotic spread

• Diffuse (disseminated) cutaneous leishmaniasis: Multiple, widespread nontender, nonulcerating cutaneous papules and nodules; analogous to lepromatous leprosy lesions

• Leishmaniasis recidivans: Presents as a recurrence of lesions at the site of apparently healed disease years after the original infection, typically on the face and often involving the cheek; manifests as an enlarging papule, plaque, or coalescence of papules that heals with central scarring (ie, lesions in the center or periphery of an old healed leishmaniasis scar); relentless expansion at the periphery may cause significant facial destruction similar to the lupus vulgaris variant of cutaneous tuberculosis

• Post–kala-azar dermal leishmaniasis: Develops months to years after the patient's recovery from visceral leishmaniasis, with cutaneous lesions ranging from hypopigmented macules to erythematous papules and from nodules to plaques; the lesions may be numerous and persist for decades

The presentation of cutaneous disease varies depending on the stage of disease, although it mainly occurs in 2 forms, (1) an oriental sore caused by L tropica and (2) American cutaneous leishmaniasis caused by L brasiliensis. Lesions are usually found in exposed areas (eg, face, arms, legs). The skin lesion begins as a nontender, firm, red papule several centimeters in size at the site of the sandfly bite. In time, the lesion becomes darker, widens with central ulceration, serous crusting, and granuloma formation. The border often has a raised erythematous rim known as the volcano sign. 

Classic Leishmania major lesion from a case in Iraq shows a volcanic appearance with rolled edges.

Active cutaneous leishmaniasis lesion with likely secondary infection in a soldier.

The lesions may be moist or open with seropurulent exudate, or the ulcers may be dry with a crusted scab and become fibrotic or hyperkeratotic with healing (after about 3-6 mo, leaving a raised border).

Healed cutaneous leishmaniasis lesions. Photo courtesy of Robert Norris, MD, Stanford University Medical Center.

Urban cutaneous leishmaniasis, caused by a subspecies of L tropica, presents as a dry cutaneous ulcer on the face and has an urban distribution. The incubation period is approximately 2 months. It is common in Western India, North Africa, the Mediterranean region, and Middle East. A similar disease in Mexico, Honduras, and Guatemala is known as the bay sore or chiclero ulcer. It is a chronic lesion that occurs at the site of a sand fly bite.

Rural cutaneous leishmaniasis is caused by L tropica and has a rural distribution. Multiple moist cutaneous lesions appear on the extremities and are associated with marked local subcutaneous infiltration and regional lymphadenitis. Both lesions are common in Central Asia.

Other findings of cutaneous disease include eczematous, psoriasiform, varicelliform, and verrucous lesions. The area surrounding the primary lesion may exhibit lymphangitic spread with palpable cords and subcutaneous nodules. This is common in New World lesions caused by L (Viannia) braziliensis infections.

Regional adenopathy, subcutaneous nodules, and satellite lesions may be present. The lesions are usually painless and without pruritus. A generalized inflammatory reaction to migrating parasites may be present in the skin surrounding the sore. Overlying bacterial infection may complicate the natural history. Healing occurs over months to years, leaving a characteristic retracted hypopigmented scar. Untreated sores can leave depigmented retracted scars. Thus, although this form is often self-healing, it can create serious disability and permanent scars. 

Old World localized cutaneous leishmaniasis located on the trunk of a soldier stationed in Kuwait. This lesion was a 3-cm by 4-cm nontender ulceration that developed over the course of 6 months at the site of a sandfly bite. The patient reported seeing several rats around his encampment.

Cutaneous leishmaniasis lesions. Photo courtesy of Robert Norris, MD, Stanford University Medical Center.

Cutaneous leishmaniasis with sporotrichotic spread.

Atypical appearance of Leishmania major lesion with local spread beyond the borders of the primary lesion. Many of the lesions in cases from Iraq show an atypical appearance.

Post–kala-azar dermal leishmaniasis

Post–kala-azar dermal lesions are categorized into 3 types, as follows:

• Depigmented macules: The earliest lesions; present on the trunk and extremities

• Erythematous patches: Appear early in the course of disease; seen on the nose, cheeks, and chin, with a butterfly distribution; they are photosensitive and become prominent toward the middle of the day

• Yellowish pink nodules: Appear mostly on the face and replace the earlier lesions; the absence of ulceration distinguishes these nodules from those of cutaneous leishmaniasis (oriental sore)

Mucocutaneous leishmaniasis

Mucocutaneous leishmaniasis consists of the relentless destruction of the oropharynx and nose, resulting in extensive midfacial destruction.

The initial skin lesion with mucocutaneous disease is often notable for its prolonged healing time and large size. In most cases, a healed scar can be identified based on careful examination. Months to years after the initial infection, patients may have rhinorrhea, epistaxis, and nasal congestion.

The lesion commonly arises at the mucocutaneous junction around the nose and may spread inward, destroying tissues and leading to deformity that requires plastic surgery. The lesion heals with scarring, causing the typical tapir or camel nose.

Examination reveals the following features:

• Excessive tissue obstructing the nares, septal granulation, and perforation; nose cartilage may be involved, giving rise to external changes known as parrot's beak or camel's nose

• Possible presence of granulation, erosion, and ulceration of the palate, uvula, lips, pharynx, and larynx, with sparing of the bony structures; hoarseness may be a sign of laryngeal involvement

• Gingivitis, periodontitis

• Localized lymphadenopathy

• Optical and genital mucosal involvement in severe cases

Death occurs from suffocation secondary to airway obstruction, respiratory infection, and aspiration pneumonia. 

Mucocutaneous leishmaniasis. Courtesy of Kenneth F. Wagner, MD.

Visceral leishmaniasis

Visceral and viscerotropic disease may manifest with the following physical findings:

• Visceral leishmaniasis (kala-azar): Potentially lethal widespread systemic disease characterized by darkening of the skin as well as the pentad of fever, weight loss, hepatosplenomegaly, pancytopenia, and hypergammaglobulinemia

• Viscerotropic leishmaniasis: Nonspecific abdominal tenderness; fever, rigors, fatigue, malaise, nonproductive cough, intermittent diarrhea, headache, arthralgias, myalgias, nausea, adenopathy, transient hepatosplenomegaly

Patients with visceral leishmaniasis appear thin and cachetic with abdominal distention and protuberance due to massive hepatosplenomegaly (secondary to compensatory production of phagocytic blood cells) (see the image below). The liver and spleen are usually soft and easily palpated in acute disease, with splenic extension to well below the costal margin, and the patient may experience intermittent abdominal distress. Jaundice with mildly elevated enzyme levels is rarely seen and is considered a bad prognostic sign.

Visceral leishmaniasis. Courtesy of Kenneth F. Wagner, MD.

Marked splenomegaly (enlargement/swelling of the spleen) in a patient in lowland Nepal who has visceral leishmaniasis. (Credit: C. Bern, CDC) Source: Centers for Disease Control and Prevention. Parasites home: leishmaniasis. Resources for health professionals: http://www.cdc.gov/parasites/leishmaniasis/health_professionals/.

Epistaxis and petechiae and ecchymosis from severe thrombocytopenia may occur. Anemia is normochromic and normocytic and caused by various factors, including replacement of marrow by the parasites, splenic sequestration, hemorrhage, hemodilution, and hemolysis. Leukopenia is also observed and may contribute to secondary infections. Thrombocytopenia contributes to the hemorrhagic tendency observed in some cases.

Lymphadenopathy is observed in the African and Chinese forms but is rarely observed in the Indian form. Pedal edema is more common in children. Hair changes, such as alopecia and eyelash elongation, may be present. As the disease progresses, characteristic patchy darkening of the face and trunk has been described and may also affect the hands and feet.

Skin lesions that contain parasites and appear as diffuse, warty, nonulcerative lesions may occur in visceral leishmaniasis, especially in Africa. Although uncommon, xerosis may occur. Complications of visceral leishmaniasis include amyloidosis, glomerulonephritis, and cirrhosis.

In patients with human immunodeficiency virus (HIV) and visceral leishmaniasis coinfection, other atypical findings include gastrointestinal and respiratory involvement. Patients have presented with gastrointestinal ulcerations, masses, pleural effusions, and odynophagia. Spread outside of the reticuloendothelial system appears more common.

Unusual clinical presentations of visceral leishmaniasis include the following:

• Pancytopenia without splenomegaly

• Immune-mediated hemolysis

• Generalized lymphadenopathy without hepatosplenomegaly

• Massive hepatic necrosis

• Chronic liver disease

• Retinal hemorrhages (reported in immunodeficient patients)

Historically, the diagnosis of leishmaniasis has been confirmed by isolating, visualizing, and culturing the parasite from infected tissue. For confirmation of cutaneous disease, procedures consist principally of performing biopsies and obtaining dermal scrapings and/or needle aspirates. The smears are stained in Leishman, Giemsa, or Wright stains and examined under oil immersion microscope.

For visceral disease, the parasite can be detected through direct evidence (amastigotes in tissue) from peripheral blood, bone marrow, liver, or splenic aspirates. The most sensitive method is splenic puncture, although iatrogenic complications can be serious, including potentially life-threatening hemorrhage. In current practice, the high sensitivity and specificity of the recombinant K39 assay has generally made such invasive procedures unnecessary.

In endemic areas, the diagnosis of leishmaniasis is often made based on the history and physical examination. Very few of the diagnostic tests discussed in the sections below are available in developing countries.

In both the localized cutaneous and mucocutaneous forms of leishmaniasis, cell-mediated immunity to the parasite is vigorous and organism density in the skin and/or mucosa is low, especially in long-standing disease (although very early in the disease large numbers of the parasites are frequently found). Therefore, growing organisms in culture can be difficult, as can finding them in pathologic specimens.

A Practical Guide for Laboratory Diagnosis of Leishmaniasis is available through the Centers for Disease Control and Prevention (CDC). Note that serologic testing is not discussed in the CDC’s guide.

Cutaneous leishmaniasis

In more than 70% of cutaneous leishmaniasis cases, microscopy of the parasite in Giemsa stains or histologic section can reveal the parasite and should be attempted first. Culture of the organisms is an option but is unreliable (approximately 40% sensitivity), because the organisms are difficult to isolate from the lesion, especially as the lesion becomes older. Consequently, the diagnosis often is epidemiologic (travel to endemic area, clinical picture, coupled with laboratory data).

The organism grows on liquid media with fetal calf serum (eg, Schneider Drosophila medium) (positive results in 1 wk) and Novy-MacNeal-Nicolle (NNN) medium (media available from the CDC), or a biphasic medium. Cultures can produce positive results in 1-3 weeks.

Systemic leishmaniasis

Considerable experience has been gained and success achieved with using bone marrow aspirates (and especially a small piece of the spiculated core tissue) for cultivating the parasite or for looking for macrophages filled with amastigotes in the stained bone marrow aspirate smears.

A variety of immunodiagnostic serologic tests have been developed to aid in the diagnosis of systemic leishmaniasis. However, the only successfully deployed serologic tests are limited to species of Leishmania that cause visceral disease. Limitations include false-negative serologic results due to inadequate titers of antibodies late in the course of the disease and false-positive results in the setting of other infectious or autoimmune diseases.

Serologic testing is useful with the indirect fluorescent antibody (IFA) test, which is 80-100% sensitive in patients with visceral leishmaniasis who are not infected with human immunodeficiency virus (HIV). However, IFA may cross-react in patients who have leprosy, tuberculosis, malaria, schistosomiasis, Chagas disease, and African trypanosomiasis. Serologic tests such as isoenzyme or monoclonal antibody analysis are not well established.

An enzyme-linked immunosorbent assay (ELISA) can be combined with IFA and/or Western blot to increase sensitivity and specificity. Polymerase chain reaction (PCR) is being used more frequently; it is more accurate in determining new-onset leishmaniasis than serum tests (92-99% sensitivity; 100% specificity).

Cutaneous and mucocutaneous leishmaniasis generally display normal laboratory values.

Hematologic tests

Complete blood cell (CBC) count

In patients with visceral leishmaniasis, the presence of (1) normocytic normochromic anemia, (2) leukopenia with decreased neutrophils and a relative monocytosis and lymphocytosis, and (3) thrombocytopenia may occur due to parasitic bone-marrow infiltration. The severity of pancytopenia may vary with only 1 or 2 cell lines decreased.

Coagulation studies

Prothrombin and partial thromboplastin times are generally normal in visceral leishmaniasis.

Peripheral blood smear

Amastigotes are revealed inside the circulating monocytes and neutrophils. However, these are often difficult to locate because of their small numbers.

L donovani is best detected by either (1) creating thick film by producing a single straight leukocyte edge when making a peripheral smear or (2) centrifuging citrated blood and withdrawing the sediment, which is then smeared, dried, and stained. 

Leishmania donovani is one of the main Leishmania species that infects humans.

Parasitologic diagnosis using peripheral blood smear and buffy coat smear is easier in patients with human immunodeficiency virus (HIV) coinfection, because parasites are more commonly found in the circulating monocytes of these patients.

Liver function tests (LFTs)

Patients with visceral leishmaniasis may exhibit mild elevations in alkaline phosphatase, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) levels.

Other tests

Hypogammaglobinemia, circulating immune complexes, and rheumatoid factors are present in sera of most patients with visceral leishmaniasis. Rarely, immunocomplex deposition in the kidneys may lead to mild glomerulonephritis. However, renal failure is not a feature of visceral leishmaniasis.

Ancillary tests important in the diagnosis of visceral disease include measurements of lipase, amylase, gamma globulin, and albumin.

The aldehyde test and the antimony test were the initial tests used to detect hypogammaglobinemia and diagnose visceral leishmaniasis. Findings include elevated gamma globulin levels and a reversal of the albumin-globulin ratio.

For the aldehyde test, obtain approximately 1 mL of blood in a small glass tube, and add 1-2 drops of 40% formalin. The formation of milky whitelike opacity and jellification indicates a positive result. Aldehyde test findings are not positive unless the disease has been present for at least 3 months.

Antimony test findings also depend on a rise in serum gamma globulin levels. Positive findings are indicated by a white flocculent precipitate that is observed when a urea stibamine solution comes in contact with serum.

Cutaneous leishmaniasis

For cutaneous leishmaniasis, take a 3-mm punch or wedge biopsy sample from a cutaneous sore from the raised edge of an active lesion where parasites are present. Avoid samples from the necrotic center. Additional tissue can be obtained through saline aspiration, tissue scrapings, or slit incisions.

Once tissue is obtained, send touch preparations, tissue impression slides, and formalin-fixed paraffin sections for hematoxylin and eosin staining. Send touch preparations and aspirations for Giemsa staining, as well. Direct visualization of amastigotes with their red rodlike cytoplasmic kinetoplast is diagnostic and helps distinguish them from other parasites (see the image below). Brown-Hopps staining has a higher sensitivity than other staining techniques.

Finding an organism in a tissue sample depends on the parasitic burden, the efficacy of the host's immune response, any coexisting bacterial contamination of the ulcer, and the age of the lesion (findings in older lesions are frequently nondiagnostic).

Mucocutaneous leishmaniasis

For mucocutaneous leishmaniasis, tissue can be obtained through dental scrapings or mucosal granuloma biopsy, although parasites may be difficult to isolate. A nonspecific granulomatous reaction often is observed. Giemsa stain may show the organisms.

Visceral leishmaniasis

Historically, bone marrow, liver, or splenic aspirates were the key to the laboratory diagnosis of visceral disease, but in current practice the high sensitivity and specificity of the recombinant K39 assay has generally made such invasive unnecessary.

The safest and most common way to obtain tissue is through bone-marrow aspiration obtained from the sternum or the iliac crest, although splenic aspiration may be used in cases that are difficult to diagnose. Amastigote forms are revealed in plain film, and the promastigote forms are revealed in culture. Although safer than splenic puncture, the parasites are scant and may give a false-negative test result. Positivity rates of 54-86% have been obtained using bone marrow.

Splenic aspiration has a higher sensitivity than bone-marrow aspiration—as many as 98% of positive results have been obtained using splenic aspiration—but this procedure should be attempted only by experienced physicians. Splenic puncture is associated with the risk of uncontrolled hemorrhage and, therefore, should be carried out only when bone marrow examination findings are inconclusive. Contraindications include low platelet count, abnormal prothrombin time, and a spleen that is palpable 4 cm or less below the costophrenic angle.

Additional tissue can be obtained through liver biopsy and lymph node dissection.

Leishmaniasis is a disease that involves the reticuloendothelial system. The parasitized macrophages disseminate infection to all parts of the body, especially to the spleen, liver, and bone marrow.

Organism identification

Direct visualization of the Leishmania organism is diagnostic, but this can be difficult in tissue sections because of its small size (2-4 mm) and because of subtle distinguishing characteristics on routine hematoxylin and eosin (H&E) stains. Diagnosis is usually much easier using Giemsa-stained touch preparations.

Regardless of the method of preparation, identification often requires an experienced pathologist and lengthy searches using high magnification, particularly when organisms are sparse. Giemsa, Brown-Hopps, Gram, or Leishman stains are all used to enhance Leishmania organisms on touch preparations, tissue aspiration, or biopsy samples.

The parasite consists of a nucleus and a kinetoplast surrounded by a cell wall. Visualization of all 3 features (ie, nucleus, cell membrane, and kinetoplast) is required to make a diagnosis based on microscopy findings.

Amastigotes in a macrophage at 1000× magnification. Inset shows the cell membrane and points out the nucleus and kinetoplast, which are required to confirm that the inclusion seen in a macrophage is indeed an amastigote.

Free amastigotes near a disrupted macrophage. On touch preparations like this (Giemsa stain, original magnification × 1000), the amastigotes are easier to identify than on other preparations. These stains clearly demonstrate the cell membrane, nucleus, and kinetoplast; all 3 are required for definitive diagnosis.

The diagnostic sensitivity of microscopic identification of leishmanial amastigotes is typically 75-85%, but it may vary widely, depending on the size of the inoculum, the clinician's experience in sampling a proper area, the experience of the laboratory personnel in making smears or making tissue sections, and the observer's experience in finding the parasite.

Most Leishmania experts believe the ideal way to microscopically identify the parasite is with direct touch preparations from the lesion or biopsy tissue stained with Giemsa rather than with routine tissue sections.

Hepatosplenic features in visceral disease

The spleen is enlarged, with a thickening of the capsule; it is soft and fragile; its vascular spaces are dilated and engorged with blood; and the reticular cells of Billroth are markedly increased and packed with amastigote forms of the parasite. However, no evidence of fibrosis is present.

In the liver, the Kupffer cells are increased in size and number and infected with amastigote forms of Leishmania. The bone marrow is hyperplastic, and parasitized macrophages replace the normal hemopoietic tissue.

Cutaneous disease

Localized cutaneous leishmaniasis is characterized by irregular acanthosis, with or without epidermal ulceration, and dense dermal infiltrate of mixed inflammatory cells, particularly plasma cells, lymphocytes, and histiocytes. Early in the course of localized disease, organisms may be numerous and found readily in the cytoplasm of macrophages. As the lesion ages and as delayed-type immunity is upregulated, the infiltrate is replaced by noncaseating granulomata in which few or no organisms can be seen.

Ulcerated lesions are often secondarily infected by bacteria, in which case histologic changes may be nonspecific. Results with biopsy specimens obtained from old (>6 mo), partially treated, or low-burden infections are frequently nondiagnostic.

Diffuse cutaneous leishmaniasis occurs in individuals with poor cellular immunity to Leishmania parasites. Histologic diagnosis is straightforward in these cases. The dermis contains sheets of macrophages containing great numbers of amastigotes, with few lymphocytes or plasma cells.

Leishmaniasis recidivans is usually difficult to confirm because of the rarity of organisms and because of its histologic similarity to lupus vulgaris.

Post–kala-azar dermal leishmaniasis has a variable histology that is determined by the degree of host immunity and the parasite load. Granulomatous histology is seen with low numbers of organisms, whereas diffuse histiocytic or xanthomatous infiltrates may be seen with numerous organisms.

Visceral leishmaniasis

Definitive diagnosis of visceral disease is made by observing the parasite (more specifically, amastigotes in tissue) on stained Giemsa smears or by observing the culture of bone marrow, splenic, hepatic, or lymph node aspirates.

Light-microscopic examination of a stained bone marrow specimen from a patient with visceral leishmaniasis—showing a macrophage (a special type of white blood cell) containing multiple Leishmania amastigotes (the tissue stage of the parasite). Note that each amastigote has a nucleus (red arrow) and a rod-shaped kinetoplast (black arrow). Visualization of the kinetoplast is important for diagnostic purposes, to be confident the patient has leishmaniasis. (Credit: CDC/DPDx) Source: Centers for Disease Control and Prevention. Parasites home: leishmaniasis. Resources for health professionals: http://www.cdc.gov/parasites/leishmaniasis/health_professionals/

In vitro cultures of tissue are regularly obtained to aid in leishmaniasis diagnosis and to help identify difficult Leishmania species. This technique has approximately the same diagnostic sensitivity as that of pathologic evaluation, but special laboratory capabilities and technical skills are required. These are available in only 2 reference laboratories in the United States (ie, the Centers for Disease Control and Prevention [CDC], Walter Reed Army Institute of Research).

The value of this method is that the species of the parasite can be identified on the basis of long-standardized isoenzyme patterns on cellulose acetate electrophoresis after the parasite is grown in vitro using both the New World methods of Kreutzer and the Old World methods of Dedet.

Specimens may be cultured on Novy-MacNeal-Nicolle (NNN) medium (rabbit-blood agar that has an overlay of Locke solution with added antibiotics), rabbit blood agar, Schneider Drosophila medium, or a multitude of specialized media to induce promastigote growth. Cultures usually take a few days to 2 weeks to demonstrate growth. Positive culture results occur approximately 75% of the time.

Additional cultures can be performed by inoculating tissue into the footpad and nose of hamsters or certain highly susceptible mouse strains (ie, in vivo cultures via animal inoculation). This is a sensitive method, especially in difficult cases, but results can take several weeks to months.

With successful culture, the parasite can be sent to specialized facilities or the Centers for Disease Control and Prevention (CDC) for polymerase chain reaction (PCR), isoenzyme electrophoresis, or monoclonal antibody speciation.

Specific leishmanial antigens prepared from cultures have been used in a number of tests. Serologic detection of antibodies to recombinant K39 antigen (eg, K39 immunochromatographic test, K39 strip test)[16] (see the following image) using a direct agglutination test (DAT), immunofluorescence assay (IFA), or enzyme-linked immunosorbent assay (ELISA) has been shown to be highly sensitive and specific in diagnosing visceral leishmaniasis and post–kala-azar dermal leishmaniasis.[17] A nitrocellulose dipstick test has also been used with K39 testing.

Illustration of one form of the rK39 test for the serologic diagnosis of visceral leishmaniasis. It is an easy, very sensitive, and specific test for visceral disease. In this case, the dipstick second from the left shows a positive result and all the rest show reaction only at the control line.

Recombinant K39 reactivity appears to correlate with active visceral disease caused by L donovani, L chagasi, and L infantum and is absent in cutaneous and mucocutaneous infections. Studies confirmed its diagnostic utility in India and Brazil but showed limited utility in Sudan because of regional species variance.[18, 19, 20] It is important to note that cross-reactions can occur with leprosy, Chagas disease, malaria, and schistosomiasis.

K39-based antigen testing is the only FDA-cleared rapid serologic test available that has undergone the necessary rigors of scientific testing to reliably trust for diagnosing visceral leishmaniasis.[21, 22]

DAT detects the specific immunoglobulin M (IgM) antibody at an early stage and has been found to be useful in the detection of both clinical and subclinical leishmaniasis infections. Because this test is easy to perform and the results are available in 24 hours, it can be used as a rapid test in primary care settings.

Before the use of specific leishmanial antigens, nonspecific antigens were used. These include the Witebsky, Kingenstein, Kuhn (WKK) antigen from the tubercle bacilli and an antigen from the Kedrowsky acid-fast bacillus. False-positive results occur in patients with tuberculosis, leprosy, and tropical Eosinophilia infection.

Over the past several years, significant advances in polymerase chain reaction (PCR) techniques have allowed for the highly sensitive and rapid diagnosis of specific Leishmania species. PCR can identify parasite DNA using sequences from the variable region of kinetoplast DNA.[23] However, a negative serologic test result does not exclude the possibility of a leishmanial infection.

Although limited to military and reference laboratories, leishmanial PCR diagnosis is becoming more widely available in developing-world laboratories and field sites.[24, 25] Even in remote locations and under harsh conditions, this technique has proven its worth, as evidenced by the US military's experience with Leishmania infection in Iraq. Molecular genetic studies can be carried out in various specimens including blood, bone marrow, or tissue.[26]

Validated genus-specific PCR primers exist, and approval of this assay by the US Food and Drug Administration (FDA) has been sought so that it can be used in worldwide facilities certified by the College of American Pathologists (CAP). Species-specific PCR probes allow for rapid speciation in confirmed cases of leishmaniasis, and some are undergoing final validation.

Note: Although many laboratories worldwide offer species-level PCR diagnostics, few have undergone the scientific rigor of complete validation necessary to assure accuracy of these species diagnostics. Many of these assays are suspect and may be misleading.

Consequently, in the United States, FDA approval of these assays should be sought, or the assays should be performed in certified laboratories in order to be confident of the results. Difficult cases should be referred to reference laboratories in the United States for rapid diagnosis and speciation, such as the Walter Reed Army Institute of Research Leishmania Diagnostic Laboratory or the Leishmania Diagnostic Laboratory at the US Centers for Disease Control and Prevention (CDC).

In visceral leishmaniasis, an elevated serum immunoglobulin level with polyclonal spike may be present on serum plasma electrophoresis (SPEP). Visceral disease was traditionally diagnosed based on the addition of formaldehyde to a serum sample (aldehyde test), which would increase the viscosity secondary to excessive immunoglobulins.

Cellulose acetate electrophoresis is a well-standardized method for determining the species of parasites grown from clinical samples. Although this test is standardized, it requires experience and special facilities; therefore, it is available only in highly specialized diagnostic facilities.

No skin tests for leishmaniasis are approved for use in the United States, primarily due to the lack of standardization of these tests.

The Leishmanin skin test (LST), also known as the Montenegro skin test (for its introduction in Montenegro, South America) is similar to the purified protein derivative (PPD) used for Mycobacterium tuberculosis. This test has been used in the developing world to determine delayed-type hypersensitivity reactions.

Killed promastigotes are injected intradermally; a 5-mm area of induration over 48-72 hours suggests past infection (ie, results are negative during active visceral leishmaniasis; positive results occur 2-3 months after infection, usually after successful therapy. The test results are also positive in patients with post–kala-azar dermal leishmaniasis).

The 2 main drawbacks of this test are that acute infections cannot be identified (in endemic regions, >70% of the population will test positive), because it remains positive for life, and those who are immunosuppressed (immunologically anergic patients) may not mount a response. Thus, this test is not used to distinguish between active and resolved disease, but it can be useful in evaluating known naive populations that become immunologically responsive to leishmanial antigens (ie, epidemiologic purposes).

When to treat

Given the associated morbidity, always treat visceral, mucocutaneous, and severe forms of cutaneous leishmaniasis. Patients should receive treatment at facilities experienced in treating the disease as per latest guidelines.

Owing to its potential to progress into mucocutaneous leishmaniasis, definitively treat New World cutaneous leishmaniasis caused by members of the Leishmania Viannia subgenus. Cases due to L tropica (Old World) and some L major from certain regions of Afghanistan may have a more aggressive or chronic course (up to years); L tropica has been implicated in occasional cases of recidivans or viscerotropic leishmaniasis. As such, treatment may need to be more involved in cases caused by this species.

In New World leishmaniasis, estimates of recurrence range from less than 5% to as many as 10% of untreated individuals experiencing chronic ulcers, recidivans lesions, or mucocutaneous involvement. Because of this, treatment is very often the standard of care, and parenteral therapy is usually the treatment of choice.

New World cutaneous leishmaniasis due to L mexicana is not associated with mucocutaneous leishmaniasis and may not require systemic treatment. Cutaneous leishmaniasis acquired in the Old World tends to resolve spontaneously (eg, L major from Iraq), but patients with this infection should receive treatment if the lesions are disfiguring, painful, infected, over joints, or slow to heal.

Individualized management

Tailor treatment to the individual, because leishmaniasis is caused by many species or subspecies of the Leishmania protozoa, all of which have different degrees of virulence and clinical predilections. Consider the clinical pattern of disease, the geographic region in which the infection occurs, the immunologic status of the patient, and the previous attempts at treatment when therapy is started.

Treatment options

In general, if the case is not advanced with serious gastroenterologic, hematologic, or infectious issues, care can be accomplished on an outpatient basis. However, daily visits to a physician for medication may be required.

Multiple medical treatment options are used throughout the world for cutaneous disease. In addition to parenteral and oral medications (see Medication), local therapies for some forms of cutaneous leishmaniasis include (1) cryotherapy, (2) infiltration of sodium stibogluconate at 0.3-0.8 mL, (3) local heat therapy at 40-42°C, and (4) various topical paromomycin preparations, typically 15% with 10% urea.

Of primary importance in dealing with leishmaniasis is the treatment of malnutrition, concurrent systemic illness (eg, human immunodeficiency virus [HIV] infection, tuberculosis), or local infection (secondary bacterial). Malnourished individuals are at greater risk of acquiring leishmaniasis, have increase morbidity and mortality in mucocutaneous and visceral disease, and respond less well to treatment than those with adequate nutrition.

Other things to consider include the following:

• At the onset of therapy, admit patients for laboratory and cardiac monitoring; alternate drug regimens require variable monitoring levels commensurate with their known adverse effects

• Administer antibiotic therapy to treat superimposed bacterial wound infections, and consult an infectious disease specialist or a dermatologist for definitive diagnosis and treatment

• Provide supportive care for patients with visceral and severe mucocutaneous leishmaniasis, as required; supportive treatment includes rest, a high-protein and high-calorie diet, blood transfusions, and wound care

• The earliest sign of improvement is an improvement in symptoms; regression of splenomegaly takes a few months

Despite successful clinical outcomes, the question of whether the parasites are completely eradicated is unclear, because reactivation of leishmaniasis with immunosuppression has been reported.[27]

Immunization

In some areas of the world (eg, Russia, Middle East), live-attenuated L major promastigotes have been used preemptively to immunize against Old World cutaneous leishmaniasis. This practice produces a modified form of the disease and results in a scar at the injection site. Immunity to subsequent L major infections is usually good; however, as with natural infection, cross-reactive immunity to other Leishmania species does not occur.

Many more universally useful and cosmetically acceptable Leishmania vaccine formulations are under investigation. To date, no vaccines are commercially available.

Treatment guidelines

The guideline summary Guidelines for prevention and treatment of opportunistic infections in HIV-infected adults and adolescents. Recommendations from CDC, the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America may be of interest.[28] Recent updates to the guideline can be found at the AIDSinfo website.[29]

The Infectious Diseases Society of America is in the process of developing a new Clinical Practice Guidelines on Leishmaniasis. 

The WHO guideline for the treatment of visceral leishmaniasis in HIV co-infected patients in East Africa and South-East Asia was published in July 2022. It provides evidence for combination therapy for management of visceral Leishmaniasis with liposomal amphotericin B  plus miltefosine and also for secondary prophylaxis after an initial episode of VL.

Leishmaniasis therapies available in the United States are limited and include the following[2] :

• Antiparasitic pentavalent antimonial agents

• Liposomal amphotericin B

• Oral miltefosine

• Pentamidine

• Other agents

• Antibiotics

Antiparasitic pentavalent antimonial agents

The treatment mainstays of leishmaniasis are the pentavalent antimony compounds first introduced in the 1930s. The 2 available preparations, sodium stibogluconate (Pentostam), produced in Great Britain, and meglumine antimonate (Glucantime), produced in France, have similar efficacy. Depending on the species and region, cure rates of 80-100% have generally been reported.

Sodium stibogluconate is only available from the CDC under an Investigational New Drug (IND) protocol. Military personnel may receive sodium stibogluconate from the Walter Reed Army Medical Center. This agent has been for the treatment of cutaneous and mucocutaneous leishmaniasis in the United States; it has also been the drug of choice in the treatment of visceral leishmaniasis, except for in Europe and regions in India with stibogluconate resistance.

In the United States, patients are sometimes monitored as inpatients when pentavalent antimony is administered, but more accepted is the use of infusion centers that complete full evaluations prior to use of the drug. Periodic evaluation of cardiac conduction with electroencephalographic (ECG) monitoring is prudent. Perform laboratory assessments of complete blood counts; renal function; and amylase, lipase, and serum transaminases levels.

Pentavalent antimony should be used according to CDC protocol. If marked variation from the protocol is being considered, CDC experts should be consulted.

A study in Guatemala that involved a combination of intravenous (IV) stibogluconate and allopurinol showed improved efficacy against cutaneous L (Viannia) panamensis infections compared with stibogluconate alone.[30] However, this effect was not reproduced in the treatment of mucosal leishmaniasis. In many regions of the world, direct intralesional injection of pentavalent antimony is used to treat cutaneous disease, although this can be painful and is technically difficult.

In a later study of IV sodium stibogluconate involving US military personnel with cutaneous leishmaniasis caused by L (Viannia) panamensis, the efficacy of a 10-day course was validated, with a significantly reduced side-effect profile over the standard 20-day course.[31] However, the results may not be applicable to infections caused by other species of Leishmania.

Unfortunately, resistance to this agent is on the rise. In the Bihar province of India, where visceral leishmaniasis is endemic, resistance is as high as 43%.

Amphotericin B

Amphotericin B is effective against pentavalent antimony-resistant mucocutaneous disease and visceral leishmaniasis. Its use is limited because of its toxic adverse effect profile. The newer lipid preparations (amphotericin B lipid complex, liposomal amphotericin B, and amphotericin B colloidal dispersion) are more active, better tolerated, and are being used as first-line therapy against visceral leishmaniasis, but the response with cutaneous disease has been mixed, and treatment is costly.

Liposomal amphotericin B is the drug of choice for visceral leishmaniasis because of its shorter course and lower toxicity.

In an open-label comparative study, Sundar et al found that the efficacy of a single infusion of liposomal amphotericin B was equivalent to a conventional amphotericin B infusion (15 alternate-day infusions) for visceral leishmaniasis.[32] Additionally, the liposomal group was less expensive and exhibited fewer infusion-related adverse effects (eg, fever, rigors) compared with conventional amphotericin B.[32]

A separate study by Sundar et al suggested that varied combinations of drugs, including liposomal amphotericin B, miltefosine, and paromomycin (for durations as short as 7-10 days), provide effective, safer, and cheaper regimens compared with the conventional 30-day amphotericin B regimen for visceral leishmaniasis.[33]

A single-dose treatment with liposomal amphotericin B has shown a 91% cure rate in India.[34] In endemic areas of north India, liposomal amphotericin is used in combination with miltefosine.[35] A short-course regimen consisting of a single dose of liposomal amphotericin followed by 7-14 days of miltefosine has resulted in cure rates of over 90%.[35] The single-dose liposomal amphotericin B regimen has become affordable after its inclusion in India’s Kala-azar Programme, assisted by drug donations facilitated by the WHO.

Response to liposomal amphotericin B may be suboptimal in patients infected with human immunodeficiency virus (HIV).[36]

Oral miltefosine

The discovery of an affordable, orally administered, well-tolerated therapy for visceral leishmaniasis has made mass treatment of the disease in the developing world a reality. Miltefosine is the sole oral agent that has been shown to be effective against leishmaniasis. This drug is a phosphocholine analogue that was originally developed as an antineoplastic agent; it interacts with membrane synthesis and signal production.

Phase 2 and 3 drug studies in India showed orally administered miltefosine was 95-97% effective in curing patients with Indian visceral leishmaniasis.[37] Oral treatment of 2.5 mg/kg/day lasting 4-6 weeks was generally well-tolerated. Common adverse effects included gastrointestinal distress and elevated creatinine levels, which resolved with cessation of therapy.

Another visceral leishmaniasis treatment study, which compared oral miltefosine with IV amphotericin B deoxycholate, showed a final cure rate after 6 months of 94% and 97%, respectively.[38, 39]

A 2011 phase IV trial from Bangladesh found monotherapy with oral miltefosine (2.5 mg/kg/d) for 28 days effective in the treatment of visceral leishmaniasis in children and adults.[40] This medication is approved in India for visceral leishmaniasis.

In August 2013, the Centers for Disease Control and Prevention (CDC) expanded access of the investigational new drug (IND) protocol in effect with the Food and Drug Administration (FDA) to make miltefosine available directly from the CDC for treatment of free-living amebae (FLA) in the United States (eg, primary amebic meningoencephalitis [PAM] caused by Naegleria fowleri and granulomatous amebic encephalitis caused by Balamuthia mandrillaris and Acanthamoeba species.[41]

In March 2014, the FDA approved oral miltefosine for visceral leishmaniasis due to L donovani; cutaneous leishmaniasis due to L braziliensis, L guyanensis, and L panamensis; and mucosal leishmaniasis due to L braziliensis.[2, 38] FDA approval was for patients who are aged 12 years or older, weigh at least 66 lb, and are not pregnant or breastfeeding.[2]

Intramuscular pentamidine

Intramuscular pentamidine is effective against visceral leishmaniasis, but this drug is associated with persistent diabetes mellitus and disease recurrence. Pentamidine is the drug of choice to treat L (Viannia) guyanensis in French Guyana, where antimonial resistance is prevalent.[42]

Other agents

Orally administered ketoconazole, itraconazole, fluconazole, allopurinol, and dapsone have been examined internationally, but none is as effective as the pentavalent antimony compounds. However, given their minimal adverse effect profile, these agents may be useful in accelerating the cure in patients with cutaneous leishmaniasis that does not progress to mucosal disease and tends to self-resolve.

Dapsone was shown to be effective in most cases of Indian cutaneous leishmaniasis after 6 weeks of therapy.[43]

Ketoconazole has a variable cure rate for New World cutaneous leishmaniasis, depending on the species. One study showed a 89% cure rate for individuals infected with L mexicana compared with 30% for L (Viannia) braziliensis.[30] Efficacy against L (Viannia) panamensis in Panama and L major in Iran and Israel has been demonstrated, whereas no effect was noted against L tropica in India and Turkey.[44]

Fluconazole was reportedly effective against 79% of patients infected with uncomplicated cutaneous leishmaniasis caused by L major in Saudi Arabia.[45]

Antibiotics

Patients with leishmaniasis may have concurrent systemic illness or local infection. Visceral leishmaniasis is an important opportunistic infection associated with acquired immunodeficiency syndrome (AIDS), and patients co-infected with human immunodeficiency virus (HIV) can develop unusual manifestations of leishmaniasis. Guidelines for prevention and treatment of opportunistic diseases in patients with HIV infection have been established.[28, 29]

Pentamidine is a first-line medication in cutaneous leishmaniasis except for L mexicana (ketoconazole 600 mg PO qd for 28 days). It is a treatment alternative in visceral leishmaniasis. Available antibiotic preparations include pentamidine isethionate (Pentam) and pentamidine dimethanesulfonate (Lomidine). Pentamidine dimethane sulphonate administered in the same dose schedule is more effective than pentamidine isethionate.

Treatment of cutaneous leishmaniasis differs according to the etiology and geographic location of the infection. For certain types of cutaneous leishmaniasis where the potential for mucosal spread is low, topical paromomycin can be used. If only one or a few small lesions are present (excluding face or over a joint), careful follow-up without drug treatment may be appropriate.

For more invasive lesions (eg, those failing to respond to topical treatment; metastatic spread to the lymph nodes; or large, disfiguring, and multiple skin lesions, especially those on the face, near mucosal surfaces, or near joints), sodium stibogluconate or pentamidine can be used.

Oral miltefosine

Treatment of New World cutaneous leishmaniasis has met with variable levels of success. In a randomized controlled trial from Brazil, miltefosine used alone was significantly better than parenteral stibogluconate in older children and adults.[46] In Colombia, miltefosine treatment cured 91% of infections involving L (Viannia) panamensis, similar to antimony therapy, while curing only 53% of infections involving L (Viannia) braziliensis in Guatemala, well below historic antimony cure rates.

However, another study in Bolivia showed oral miltefosine given for 28 days yielded an 82% cure rate compared with 88% for intramuscularly administered meglumine antimonate against L (Viannia) braziliensis.[47] The tolerance for oral miltefosine was so superior to intramuscularly administered meglumine antimonate that the researchers were unable to convince local treating physicians to continue treating the control group with the intramuscular therapy.

Topical paromomycin

Topical paromomycin has been shown to be effective against cutaneous leishmaniasis caused by L major and L mexicana. Because these species do not tend to cause visceral or mucocutaneous disease, topical paromomycin can spare the patient systemic adverse effects associated with parenteral medications. Topical therapy is not recommended for treatment of New World species that are known to progress to mucocutaneous disease.

In a randomized, double-blind, parallel group–controlled study in 375 patients from a region of Tunisia where leishmaniasis is endemic, Ben Salah et al demonstrated that paromomycin topical cream, with or without gentamicin, was effective against ulcerative cutaneous leishmaniasis.[48, 49] Study subjects received 15% paromomycin, 15% paromomycin plus 0.5% gentamicin, or vehicle control (containing neither gentamicin nor paromomycin). After 20 days of treatment, paromomycin alone achieved a cure rate of 82%, paromomycin-gentamicin achieved a cure rate of 81%, and vehicle control achieved a cure rate of 58%.[48, 49]

An ointment that contains 15% paromomycin and 12% methylbenzethonium chloride showed an even higher cure rate of 87% after 20 days of topical treatment for cutaneous L major.[50] Unfortunately, the performance of this cream with infections caused by L tropica has been disappointing.

Although topical paromomycin is not commercially available in the United States, this cream may be available from compounding pharmacies and is used in Israel for the treatment of L major lesions.

Other agents and therapeutic modalities

A short course of intramuscular pentamidine for 4 days was reported to be effective for cutaneous disease in Colombia.[51] A single report from Tunisia found doxycycline to be effective in cutaneous leishmaniasis.[52]

Other reported treatments include topical imiquimod cream, cryotherapy, thermotherapy, ketoconazole, photodynamic therapy, itraconazole, and allopurinol. However, these are effective only when used in combination with the first-line drugs

Because Leishmania species are temperature-sensitive, local treatment with heat or cold provides an alternative to pharmaceutical therapy in some cases. Cryotherapy can be used on small, uncomplicated Old World lesions. A 15- to 20-second freeze-thaw-refreeze cycle repeated as needed over 1-2 weeks was sufficient to cure most cases of uncomplicated L tropica and L major infections.

In 2003, the FDA approved the ThermoMed device for the treatment of cutaneous leishmaniasis. This device heats the skin through radiofrequency waves directed to a specified area and depth. A study conducted in Afghanistan involving cutaneous disease caused by L tropica demonstrated a cure rate of 69% at 100 days after treatment.[53] However, the lesions treated in this study were small. Further studies may demonstrate this to be a useful therapy for mild disease.

Mucocutaneous disease responds to a 20-day course of sodium antimony gluconate; amphotericin B may be used to treat advanced or resistant cases. Pentavalent antimony for a course of 4 weeks has also been recommended.

A single arm study in adults conducted to evaluate oral miltefosine efficacy for the treatment of mucocutaneous leishmaniasis showed that by 12 months after the end of therapy, 62% of patients had complete resolution of edema, erythema, infiltration, and erosion from the involved mucosal sites.[38] The study was conducted in Bolivia, where L braziliensis is epidemiologically the prevalent species.

The protective effect against subsequent mucocutaneous disease is unknown at this time. One study showed a 1-year cure rate of 75% among Bolivian patients who presented with mild mucocutaneous leishmaniasis. The particular strain of L (Viannia) braziliensis affected an area known to have antimonial resistance. One-year cure rates were lower among patients with more severe disease. Long-term studies will be required to determine if a definitive cure was achieved.

Be alert for complications related to reticuloendothelial system failure. Patients may have bleeding or neutropenia leading to infectious conditions such as pneumonia or diarrhea. Transfusions may be necessary for severe bleeding or anemia. Antibiotics are indicated to treat intercurrent infectious conditions.

On the Indian subcontinent, the following treatment regimens are recommended for visceral leishmaniasis:

• Liposomal amphotericin B alone, given as a single dose (currently recommended as the drug of choice by the Kala-Azar elimination programme of India)
• Liposomal amphotericin B in a single dose, in combination with 7 days of oral miltefosine or 10 days of paromomycin
• Miltefosine plus paromomycin for 10 days
• Amphotericin B deoxycholate: 0.75-1 mg/kg/day via infusion, daily or on alternate days for 15-20 doses
• Miltefosine orally for 28 days or paromomycin intramuscularly for 28 days
• Pentavalent antimonials: 20 mg Sb5+/kg/day intramuscularly or intravenously for 30 days in areas where they remain effective: Bangladesh, Nepal, and the Indian states of Jharkhand, West Bengal, and Uttar Pradesh ^{[13, 54]}

Outside of India, treatment with a pentavalent antimonial compound is usually effective. The use of an alternative parenteral agent should be considered even for first-line therapy in areas where resistance to pentavalent antimony therapy is prevalent, as it is in India, or if nonantimonial therapy would be advantageous for other reasons (eg, toxicity profile, duration of therapy).

The advent of liposomal formulations of amphotericin B, which passively target amphotericin to macrophage-rich organs, have generally replaced the deoxycholate formulations. As noted earlier, liposomal amphotericin B is much more costly than conventional amphotericin B (making them cost-prohibitive in poor countries), but they are associated with less nephrotoxicity and can be given in considerably shorter courses. Although visceral leishmaniasis is traditionally treated with multiple doses of amphotericin B deoxycholate, it appears, based on a single randomized trial, that a single dose of liposomal amphotericin B may be just as effective and cheaper.[32]

Other parenteral alternatives that have merit include amphotericin B (not only in deoxycholate form but also in liposomal forms) and have generally replaced pentamidine. Injectable paromomycin has also been reported to be noninferior to amphotericin B.

Oral miltefosine is FDA approved for visceral, cutaneous, and mucocutaneous leishmaniasis. Sitamaquine is another oral therapy in the research pipeline for the treatment of visceral disease. Originally discovered by the Walter Reed Army Research Institute, this 8-aminoquinoline is currently undergoing phase 3 trials in Kenya and India.

Resistant visceral leishmaniasis

Drug resistance can be primary or secondary. Causes include (1) delayed diagnosis (prolonged duration of illness), (2) interrupted and low-dose treatment, (3) immunologic failure, (4) emergence of resistant strains of parasites, and (5) leishmaniasis associated with acquired immunodeficiency syndrome (AIDS).

Patients with stibogluconate-resistant disease should be treated with alternative agents, such as liposomal amphotericin (0.5-3 mg/kg) on alternate days until a dose of 20 mg/kg or pentamidine (2-4 mg/kg) on alternate days for 15 doses. Pentamidine is available in 2 preparations: pentamidine isethionate (Pentam 300) and pentamidine dimethane sulphonate (Lomidine). However, the effectiveness of pentamidine has recently declined.

Liposomal amphotericin has reported cure rates of more than 90% in various studies. However, the high cost of this drug is a disadvantage to its use in areas where visceral leishmaniasis is prevalent.

Another alternative agent is oral miltefosine. Miltefosine did not prevent visceral relapse in patients co-infected with human immunodeficiency virus (HIV) but remained effective with retreatment and over prolonged periods of therapy.[55]

A shift from monotherapy to multidrug combinations in short courses delivered at no or affordable cost, through directly observed therapy, appears to be the only way to effectively treat and prevent drug resistance. Combination therapy of stibogluconate with drugs such as aminosidine and interferon gamma has also produced good results in patients who with a poor response to stibogluconate therapy alone. Aminosidine, an aminoglycoside identical to paromomycin, has also been found to be effective in trials in India.

Guidelines for prevention and treatment of opportunistic diseases in patients with HIV infection have been established.[28, 29] Visceral leishmaniasis is an important opportunistic infection associated with AIDS, and patients co-infected with HIV can develop unusual manifestations of leishmaniasis. Research is being carried out on newer drug delivery systems for amphotericin, including the use of nanoparticles and cochleates, but these investigations have yet to enter human trials.[56]

Surgical excision to manage leishmaniasis is not usually recommended because of the following risks:

• Relapse (exacerbation of quiescent disease)

• Recurrence at the excision site

• Cosmetic disfigurement

Surgical intervention may be necessary for adjunctive splenectomy in patients with treatment-resistant disease. Patients with severe mucocutaneous leishmaniasis may require orofacial surgery.

Carefully monitor patients with leishmaniasis for relapse or recrudescence for up to 6 months after successful treatment.

Perform a follow-up evaluation for patients 6 weeks after last dose of pentavalent antimony. Drug-resistant strains of leishmaniasis are appearing because of the unregulated use of these compounds. Improper dosing and shortened duration of therapy are contributing factors. Improvement in cutaneous disease is expected within the first couple of weeks of treatment. Patients with visceral disease should defervesce around 72 hours, with resolution of hepatosplenomegaly by 28 days.

Severe leishmaniasis recidivans, mucocutaneous leishmaniasis, diffuse cutaneous leishmaniasis, and post–kala-azar leishmaniasis are often difficult to treat and may require prolonged therapy.

Retreatment or second-line drugs may be required in patients with resistant disease.

Prescribe hematinics until the patient’s hemoglobin levels return to within the reference range.

Early diagnosis and treatment are the main measures for controlling leishmaniasis.

Postinfection immunity

After successful treatment, patients generally acquire immunity (97-98% effective) from the Leishmania species with which they were infected. Abortive infections due to therapy with effective agents are felt to reduce the protective immunity often seen with full course, self-resolving infections.

Vaccination

In some areas of the world, children are superficially inoculated with infected material in concealed areas to induce infection, to promote immunity, and to prevent facial scarring.

Some studies have shown protection against cutaneous leishmaniasis with vaccination of killed Leishmania promastigotes and live bacillus Calmette-Guérin (BCG). However, this does not seem to be protective against visceral leishmaniasis.

Attempts to create a viable human vaccine along similar lines have been met with difficulty and have resulted in persistent cutaneous lesions. In May 2005, French researchers from the IRD Montpellier Research Centre successfully developed a novel vaccine against visceral leishmaniasis in dogs.[57] Using antigen proteins excreted by the parasite at the 100- and 200-mcg dose, 100% of the dogs (9 of 9) showed immunity over a period of 2 years after infection with L infantum.

Immunity appears to be related to activation of the Th1 lymphocytes, allowing macrophages to produce nitric oxide and to clear the Leishmania parasites. Researchers postulate that, by reducing the disease burden in dogs, the transmission cycle can be interrupted, indirectly reducing human infections. This new approach is currently being evaluated for incorporation into human vaccines.

Other measures

Reservoir eradication, vector control, and mass treatment of individuals who are infected have met with some success, but these are limited by cost and difficulty in coordinating efforts.

Insect repellent (eg, diethyltoluamide [DEET]), protective clothing, fans, and permethrin- or deltamethrin-impregnated mosquito nets offer some protection for visitors to endemic areas. The female sandfly makes no audible noise, is a relatively poor flyer, and is small enough to pass through standard mosquito nets; thus, specially designed, fine-mesh netting is required. Minimizing outdoor exposures at peak times (dawn to dusk) should also be used.

Because leishmaniasis can be transmitted through blood, infected patients should not donate blood or organs.

The goals of pharmacotherapy are to eradicate the leishmaniasis infection, to reduce morbidity, and to prevent complications, recurrence, and the development of mucocutaneous forms of the disease.

Antiparasitic pentavalent antimonial agents

Antiparasitic pentavalent antimonials, such as sodium stibogluconate (Pentostam) or meglumine antimonate, have been the mainstays of therapy for all forms of the disease.[58] Until recently, sodium stibogluconate was the drug of choice in most areas and the only recommended treatment in the United States, but resistance is rising.

Pentavalent antimony is not marketed in the United States, but it can be obtained through the Centers for Disease Control and Prevention (CDC) Drug Service (404-639-3670), under an Investigational New Drug (IND) approved by the Food and Drug Administration (FDA), and by the CDC’S Institutional Review Board (IRB).[2]

Cure rates

Cure rates for pentavalent antimony are 90-97% with 1-3 full intravenous treatment courses; however, the drawbacks are considerable. These drugs are expensive and difficult to obtain. They must be delivered parenterally, they have numerous adverse effects, they may have lot-to-lot variability, and they are becoming increasingly less effective because of the emergence of drug-resistant parasites (especially in certain countries such as India). Interferon-gamma plus antimony may be an alternative option with an acceptable cure rate.

In other parts of the world, intralesional injections have shown promise with less toxicity (although with much lower patient tolerability owing to the pain associated with the intralesional injections).

Alternative treatment regimens with acceptable cure rates but that are not FDA approved for treating selected cases of leishmaniasis are parenteral agents pentamidine and amphotericin B deoxycholate, as well as oral agents ketoconazole, itraconazole, and fluconazole.[2]

However, although much has been made of the use of azoles for the Iraqi L major cutaneous disease, few practitioners in the field believe this is a prudent consideration for routine treatment of this disease. Liposomal amphotericin B has been used with good success in the treatment of cutaneous disease from many parts of the world and is gaining increased acceptance with many practitioners.

Although paromomycin also has acceptable cure rates, it is not available in the US or potentially available only through specific channels.[2]

Liposomal amphotericin B

Amphotericin B in its liposomal form (as opposed to amphotericin B deoxycholate) is now considered to be the drug of choice for visceral leishmaniasis because of its shorter course and lower toxicity. This agent is not approved for the cutaneous or mucosal forms of the disease.[2]

Cost issues prevent the use of liposomal drugs in most countries, where the mainstay of treatment is still prolonged intravenous treatment with antimonial agents, despite ever-increasing patterns of resistance and an increasing incidence of treatment failures. Alternative treatments, such as amphotericin B, should be used when resistance is endemic or when other reasons for using an alternative parenteral exist (eg, lower toxicity profile).

Oral miltefosine

Miltefosine is the sole oral agent that has been shown to be effective against leishmaniasis. This medication was developed first as an antineoplastic agent and later found to have considerable antiproliferative activity against leishmaniasis as well as against other trypanosome parasites. It is an attractive agent in areas, such as India, that have drug resistance against traditional chemotherapy.

In August 2013, the CDC made available an expanded access investigational new drug (IND) protocol for miltefosine for treatment of free-living amebae (FLA) in the United States.[41] In March 2014, the CDC approved miltefosine for the treatment of specific species that cutaneous, mucosal, and visceral leishmaniasis, in adults and adolescents who aged at least 12 years, weigh at least 66 lb, and are not pregnant or breastfeeding.[2]

This medication is approved in India for visceral leishmaniasis.

Class Summary

Antifungal and antiparasitic medications are used in resistant leishmaniasis in combination with other agents. The mechanisms of action may involve an alteration of RNA and DNA metabolism or an intracellular accumulation of peroxide that is toxic to the fungal cell. The major sterol in Leishmania organisms and fungi is ergosterol. Antiergosterol agents are marketed as antifungals.

When systemic agents are administered, monitor patients for adverse effects and complications common to the drug.

Amphotericin B liposomal (AmBisome)

Traditionally, amphotericin B, produced by a strain of Streptomyces nodosus, is a fungistatic or fungicidal agent that attacks the ergosterol wall of the Leishmania parasite, causing intracellular components to leak with subsequent fungal cell death. Its use has been limited because of its high adverse effect profile, but newer lipophilic formulations that reduce toxicity have shown promise in treating resistant visceral and mucocutaneous disease. These formulations are taken up well by the reticuloendothelial system and poorly by the kidney, decreasing the risk of nephrotoxicity.

Liposomal amphotericin B has become the drug of choice in antimony-resistant infections (especially if contracted in India).

In addition to miltefosine, AmBisome is the only FDA-approved drug for the treatment of visceral leishmaniasis in the United States. This agent is available as a 100 mg/20 mL preparation.

Cure rates of 90% and higher have been observed in various studies, except possibly in patients with HIV infection. A short-course regimen consisting of a single dose of liposomal amphotericin followed by 7-14 days of miltefosine has resulted in cure rates greater than 90% in north India.

The high cost of liposomal amphotericin B is a disadvantage to its use in areas where visceral leishmaniasis is prevalent.

Ketoconazole

Ketoconazole is an imidazole broad-spectrum antifungal agent that inhibits synthesis of ergosterol, causing cellular components to leak and resulting in fungal cell death.

Itraconazole (Sporanox, Onmel)

Itraconazole is a synthetic triazole antifungal agent that slows fungal cell growth by inhibiting CYP-450–dependent synthesis of ergosterol, a vital component of fungal cell membranes.

Class Summary

Xanthine oxidase inhibitors may be added to first-line drugs for treatment against protozoal infections.

Allopurinol (Zyloprim, Aloprim)

Allopurinol inhibits xanthine oxidase, the enzyme that synthesizes uric acid from hypoxanthine. This reduces the synthesis of uric acid without disrupting the biosynthesis of vital purines.

Allopurinol is not effective as monotherapy for leishmaniasis.

Class Summary

Antiprotozoan compounds are the drugs of choice in patients with visceral leishmaniasis. Parasite biochemical pathways are sufficiently different from the human host to allow selective interference by chemotherapeutic agents in relatively small doses.

Protozoal infections are typically more severe in immunocompromised patients than in immunocompetent patients. These infections occur throughout the world and are a major cause of morbidity and mortality in some regions. Primary immune deficiency is rare, whereas secondary deficiency is more common.

Immunosuppressive therapy, cancer and its treatment, infection with human immunodeficiency virus (HIV), and splenectomy all may increase vulnerability to infection. The infectious risk is proportional to neutropenia duration and severity.

Pentamidine (Pentam)

Pentamidine is a first-line medication in cutaneous leishmaniasis except for L mexicana (ketoconazole 600 mg PO qd for 28 d). It is a treatment alternative in visceral leishmaniasis.

This agent inhibits growth of protozoa by (1) interacting with trypanosomal kinetoplast DNA, (2) interfering with polyamine synthesis by a decrease in the activity of ornithine decarboxylase, and (3) and inhibiting incorporation of nucleic acids into RNA and DNA, causing inhibition of protein and phospholipid synthesis.

Pentamidine is well absorbed and highly tissue bound. This medication is formulated as a sterile powder and must be reconstituted and administered as slow IV infusion or via the IM route. Because patients receiving daily injections do not reach a steady-state plasma concentration and elimination half-life is 12 days, a great deal of accumulation of pentamidine can occur in tissues such as the liver, kidney, and spleen.

Resistance to pentamidine is common in India, with high relapse rates reported.

Paromomycin

Paromomycin is an oral orphan drug consisting of an amebicidal and antibacterial aminoglycoside obtained from a strain of Streptomyces rimosus that is active in intestinal amebiasis.

Paromomycin has a relatively favorable adverse effect profile, but it is not as effective as antimony or amphotericin B for visceral disease when used as monotherapy. Paromomycin can be used in combination with sodium antimony gluconate to reduce the total time of therapy, and it has better cure rates.

Intravenous and topical paromomycin products are not available in the United States.

Class Summary

Interferons are naturally occurring cytokines that possess various biologic functions, which include immunosuppressive action. They are produced by cells in response to viruses, double-stranded RNA, antigens, or mitogens, and are classified in relation to biochemical properties and cell of origin. Interferons are commercially produced with recombinant DNA technology.

Interferon gamma-1b (Actimmune)

Interferon gamma-1b is a naturally occurring cytokine that possesses antiviral, immunomodulatory, and antiproliferative activity. This agent is commercially available as a protein product manufactured by recombinant DNA technology.

Interferon gamma-1b is administered with sodium antimony gluconate (probably ineffective alone).

Class Summary

Miltefosine is a new oral drug that is now approved in the United States to treat cutaneous, mucocutaneous, and visceral disease from specific Leishmania species. The antiprotozoal effect is poorly understood.

Sodium stibogluconate is a compound available in English-speaking countries, and meglumine antimonate is a compound available in Latin American countries.

Sodium stibogluconate (Pentostam)

Sodium stibogluconate has been the drug of choice for the treatment of cutaneous and mucocutaneous leishmaniasis in the United States. This agent is also effective against visceral leishmaniasis and is often the first-line treatment outside the United States. Patients with long-standing disease may require long-term therapy. Although not FDA approved, sodium stibogluconate is currently available from the Centers for Disease Control and Prevention (CDC) as an investigational new drug (404-639-3670).

Sodium stibogluconate acts by interfering with the metabolism of the parasite. This agent may be administered intravenously (IV) or intramuscularly (IM), with similar pharmacokinetic parameters. IV use is preferred, because large volumes are required. Sodium stibogluconate is available only from the CDC at 100 mg/mL. Dilute each mL in 10 mL of 5% dextrose water, and administer it over 15 minutes to prevent thrombophlebitis.

This agent can be administered at recommended dose for 30 days without toxicity. Children often tolerate adverse effects better than adults and may not require electrocardiographic (ECG) monitoring.

Primary unresponsiveness ranges from 2-8%. The relapse rate is usually below 10%, but it has been reported to be as high as 30% in Kenya. An increasing incidence of resistance is reported in India.

Miltefosine (Impavido)

Miltefosine is an alkylphosphocholine that was originally developed as an antineoplastic agent. The specific mode of action against Leishmania species is unknown but is likely to involve interaction with lipids (phospholipids and sterols), including membrane lipids, inhibition of cytochrome C oxidase (mitochondrial function), and apoptosis-like cell death.

In March 2014, the FDA approved miltefosine for visceral leishmaniasis caused by L donovani; cutaneous leishmaniasis due to L braziliensis, L guyanensis, and L panamensis; and mucosal leishmaniasis due to L braziliensis. FDA approval was for patients aged 12 years or older, those who weigh at least 66 lb, and those who aren't pregnant or breastfeeding.

Since 2002, this agent has rapidly become the drug of choice for visceral leishmaniasis in India. A short-course regimen consisting of a single dose of liposomal amphotericin followed by 7-14 days of miltefosine has resulted in cure rates greater than 90% in north India. Miltefosine is registered in India and Europe for the treatment of visceral leishmaniasis.

Its mechanism of action is likely due to inhibition of phospholipid and sterol biosynthesis via interference with cell signal transduction pathways. Resistance against miltefosine has been found.