Dracunculiasis 

Updated: Sep 24, 2018
Author: Vinod K Dhawan, MD, FACP, FRCPC, FIDSA; Chief Editor: Russell W Steele, MD 

Overview

Background

Dracunculiasis is an infection caused by the nematode Dracunculus medinensis, also known as the guinea worm.[1] D medinensis is in the order Spirurida, an order of parasites that includes the filariae Wuchereria bancrofti, Brugia malayi, and Loa loa.

The term dracunculus is Latin for "little dragon," a misnomer and reference to the symbol. Thus, when the guinea worm disappears, one of the original inspirations for the discipline of medicine will also disappear. Currently, the infection persists and, although uncommon, can cause significant morbidity.

During ancient times, the presence of dracunculiasis can be inferred by the universally recognized symbol of medicine, the Greek asklepios (ie, Roman aesculapius), which consists of a one-headed snake wrapped around a stick. Dead female worms have also been found in Egyptian mummies older than 3000 years, and writings in ancient Sanskrit, Greek, and Hebrew refer to Dracunculus infection. To this day, the most effective method dracunculiasis treatment involves extraction by wrapping the worm around a stick[2, 3] , as is seen in the image below.

A method used to extract a guinea worm from the le A method used to extract a guinea worm from the leg vein of a human patient.

During the last 25 years, concerted efforts to eradicate the guinea worm have been undertaken and these have resulted in a reduction of more than 99% of worldwide cases of dracunculiasis. Thanks to a relentless campaign, this is poised to become the first disease since smallpox to be pushed into oblivion. The Carter Center has led the effort to eradicate the disease, along with the CDC, the WHO, UNICEF, and the Bill and Melinda Gates Foundation.

Guinea worm disease remains endemic in 3 countries: Sudan, Mali, and Ethiopia and fewer than 1,800 cases were reported in the world in 2010. The most prominent hot spot for guinea worm disease is South Sudan, which harbors 94% of current cases. Sporadic violence and civil unrest in Sudan and Mali poses the greatest threat to the final eradication of dracunculiasis.

Pathophysiology

Dracunculiasis is caused by drinking water containing water fleas (Cyclops species) that have ingested Dracunculus larvae. The acidic environment of the stomach and duodenum kills the copepods. The larvae are subsequently released in the stomach or small intestine and penetrate the mucosa to mate and mature in the abdomen or retroperitoneal space approximately 60-90 days after initial infection. The maturation stage can last for up to 1 year, and, during this time, the adult male probably dies because only the female worm is recovered from symptomatic patients.

After maturation is complete, the female Dracunculus reaches a length of up to 1 m (with a thickness of only 1-2 mm) and slowly migrates from the GI tract into subcutaneous tissue, usually to a location in the lower extremity. The female worms move through the person's subcutaneous tissue, causing intense pain, and eventually emerge through the skin, usually at the feet, producing edema, a blister and eventually an ulcer, accompanied by fever, nausea, and vomiting. If they come into contact with water as they are emerging, the female worms discharge their larvae, setting in motion a new life cycle. Free-living larvae can survive only 3 days without a host; they become infective after 2 weeks (2 molts) within the host copepod.

Epidemiology

Frequency

United States

Dracunculiasis is rarely imported to the United States. Two cases have been reported since 1995, both occurring in individuals from Sudan.

International

In 1986, more than 3.5 million people in 20 countries were infected with guinea worm.

At the end of 2004, all of Asia was free of the disease. Sporadic cases have been noted in Australia and North America in African immigrants during the period 2000-2005. Since 2006, only sporadic cases have been reported in African nations.

From 2007-2008, indigenous infections were limited to focal areas of four countries in sub-Saharan Africa: Sudan, Ghana, Mali, and Niger. Currently, guinea worm disease remains endemic in 3 countries: Sudan, Mali, and Ethiopia and fewer than 1,800 cases were reported in the world in 2010. The most prominent hot spot for guinea worm disease is South Sudan, which harbors 94% of current cases.[4, 5, 6, 7]

There were 126 cases reported worldwide in 2014. South Sudan reported 56% of the Guinea Worm Disease (GWD) cases in 2014. The remainder of the 2014 GWD cases were from Chad, Ethiopia, and Mali.[8]

Mortality/Morbidity

Death due to dracunculiasis is not caused by the primary infection and occurs only in cases in which secondary infection of the worm's exit site leads to sepsis. The mortality rate is quite low; however, morbidity is a major concern, with secondary infection being the most common complication. Cellulitis or the formation of an abscess requires prompt attention, and pain from the exit sites often can incapacitate patients for weeks. This is usually observed in individuals who have multiple worms and rely on their ability to stand or walk for their livelihood. Farmers with untreated dracunculiasis in Nigeria have been found to miss work for up to 3 months. Infected schoolchildren may miss up to 25% of the school year. Therefore, Dracunculus infection can cause significant socioeconomic burden for individuals and communities.

Another, more chronic, complication of dracunculiasis is encapsulation of the adult worm, which occurs when the calcified remains of the worm persist in the extremity of the patient. This can result in chronic pain and intermittent swelling of the extremity. In a small percentage of individuals who have permanent scarring or deformity of the lower extremity, even after the worm has been extracted, chronic pain may persist for as long as 18 months. Notably, on average, infected individuals have multiple worm extrusions at the same time (1.8 worms per person, on average). Rarely, dracunculiasis can present with worms located in anomalous locations, including the lungs, pancreas, testes, spinal cord, or periorbital tissue.

Race

No race predilection is noted.

Sex

No sex predilection is observed.

Age

Most reported dracunculiasis cases occur in the young adult (working) population who may be exposed to contaminated water sources more frequently; however, no particular age predilection is noted.

 

Presentation

History

See the list below:

  • Travel to or residence in endemic countries is invariably part of the history in patients with dracunculiasis.

  • Recollection of ingestion of unfiltered or untreated water, ingestion of fresh fruits or vegetables washed with such water, or bathing or swimming in potentially contaminated water are all possibly elicited in the patient's history. The transmission of the disease has seasonal variation. In arid areas, the rainy season, with increased availability of surface water, coincides with most cases. In wet areas, the dry season, when sources of drinking water are limited, is associated with most cases.

  • History tends to be useful only to confirm the diagnosis after it has been presumed based on physical examination findings.

Physical

A blister forms in the epidermis at a site chosen by the female worm, usually in the lower extremity. Immediately before blister formation, allergic-type symptoms, such as mild respiratory distress with wheezing, urticaria, periorbital edema, and pruritus, are often present. Patients may also be febrile during this period. With the emergence of the worm's head, the blister grows and becomes erythematous at its periphery. Edema occurs around the site, and inflammation of the papule causes further pruritus and burning pain. Usually, after a few days, but possibly as long as 2 weeks, the blister erupts, and the worm releases a collection of larvae-containing fluid. The swelling and pain often are markedly decreased after the blister is opened. At this point, an ulcer forms around the blister site as the adult worm continues to emerge.

Definitive diagnosis is made when the head of the worm is identified within the ulcer.

As noted, the ulcer tends to become secondarily infected.

No other particular physical findings are commonly noted, although some degree of lymphadenopathy may be found at any stage of the illness.

Causes

See the list below:

  • Dracunculiasis is an infection caused by the nematode D medinensis.

  • The larvae from D medinensis are not infective unless a molting process within the copepods occurs. This requires a fresh-water environment; thus, water ingestion is the only identified mode of transmission.

 

DDx

Differential Diagnoses

  • Filariasis

 

Workup

Laboratory Studies

The following studies are indicated in dracunculiasis:

  • CBC count with differential: The WBC count is likely elevated, even if only slightly. The differential commonly indicates eosinophilia.

  • Serum immunoglobulin levels: Immunoglobulin E (IgE), immunoglobulin G1 (IgG1), and immunoglobulin G4 (IgG4) levels are usually elevated, with variability depending on the stage of disease. Patent infections (immediately following blister eruption but before ulcer formation) cause the greatest elevation of the 2 IgG subclasses, whereas both are relatively less elevated with postpatent (ulcerated) or prepatent (blister in formative stage) infections.

Imaging Studies

See the list below:

  • A radiologic examination (plain-film roentgenography) of the lower extremity may prove useful in the identification of calcified worms in the rare case when surgery is considered. Incidental identification of calcified lesions from dracunculiasis has also been reported after radiographic evaluation of a painful lower extremity.

 

Treatment

Medical Care

The mainstay of treatment is the extraction of the adult worm from the patient using a stick at the skin surface and wrapping or winding the worm a few centimeters per day. Because the worm can be as long as one meter in length, full extraction can take several days to weeks. This slow process is required to avoid breakage and leaving behind a portion of the worm.

Each day, the affected body part is immersed in a container of water to encourage more of the worm to come out. The wound is cleaned and gentle traction is applied to the worm to slowly pull it out. Pulling stops when resistance is met to avoid breaking the worm. The worm is wrapped around a stick to maintain some tension on the worm and encourage more of the worm to emerge. Topical antibiotics are applied to the wound to prevent secondary bacterial infections and the affected body part is then bandaged with fresh gauze to protect the site. These steps are repeated every day until the whole worm is successfully pulled out.

Analgesics, such as aspirin or ibuprofen, are given to help ease the pain of this process and reduce inflammation.

No specific drug is used to treat dracunculiasis. Metronidazole or thiabendazole (in adults) is usually adjunctive to stick therapy and somewhat facilitates the extraction process. However, one study found that antihelminthic therapy was associated with aberrant migration of worms, resulting in infection in areas other than the lower extremity. Therefore, such medications should be used with caution.

Surgical Care

See the list below:

  • The worm also can be excised surgically where such facilities are available.

Consultations

See the list below:

  • Suspicion of dracunculiasis based on history or examination findings warrants consultation of an infectious disease specialist for involvement in management and follow-up care. This also allows for initiation of epidemiologic protocol if the patient presents in a nonendemic country.

Diet

See the list below:

  • No particular dietary changes are required during the extraction process, regardless of the time involved.

Activity

See the list below:

  • Activity is usually self-restricted because of discomfort. Recommendations are tailored for the individual, with no particular general guidelines.

 

Medication

Antiparasitic agents

Class Summary

These agents are used to speed the pace of worm extraction.

Metronidazole (Flagyl, Protostat)

DOC as therapy adjunctive to extraction. Active against various anaerobic bacteria and protozoa. Intermediate-metabolized compounds formed bind DNA and inhibit protein synthesis, causing cell death.

Thiabendazole (Mintezol)

Acceptable for use in adults only.

Inhibits helminth-specific mitochondrial fumarate reductase; alleviates symptoms of trichinosis during invasive phase.

 

Follow-up

Further Outpatient Care

See the list below:

  • Close follow-up monitoring is necessary to track progression of extraction in patients with dracunculiasis.

  • Initially, warm compresses may be useful in relieving pain.

  • Diligent cleaning of the wound site is necessary during and following extraction of the worm.

  • Topical antibiotic ointments, such as bacitracin or mupirocin (Bactroban), can be applied to wounds to prevent secondary infection.

Deterrence/Prevention

No vaccine is available for dracunculiasis. Prevention of the disease is through the following:

  • Surveillance (case detection) and case containment

  • Provision of safe drinking water in endemic areas and filtering potentially contaminated water

  • Vector control using a chemical larvicide

  • Health education and community mobilization

Unfortunately, civil unrest and governmental lapses have prevented clearance of many water supplies in several endemic nations. Numerous positive social and political steps are also important to create conditions for the interruption of disease transmission.

Complications

In addition to the pain of the blister, removing the worm is also very painful. The wound often becomes infected by bacteria resulting in the following complications:

  • Cellulitis

  • Abscesses

  • Sepsis

  • Septic arthritis

If the worm breaks during removal, it can cause intense inflammation as the remaining part of the dead worm starts to degrade inside the body. This causes more pain, swelling, and cellulitis.

Prognosis

Prognosis is very good and death rate is low. However, disability is common. Patients are incapacitated because of pain and complications caused by secondary bacterial infections. The disability that occurs during worm removal and recovery prevents people from working in their fields, tending animals, going to school, and caring for their families. Disability lasts 8.5 weeks on average but sometimes can be permanent.

Patient Education

See the list below:

  • Distribute information regarding the disease in endemic areas.

  • Assist communities in maintaining clean drinking water supplies.