History
The majority of individuals who develop hookworm infection are from known endemic areas. They frequently have a history of wearing open footwear or walking barefoot in such areas.
Most individuals with hookworm infection are asymptomatic, [17] and diagnosis is made only by means of stool examination (see Workup). Those symptoms that do occur depend on the type of hookworm disease present (ie, classic hookworm disease, cutaneous larva migrans, or eosinophilic enteritis) and on the stage of the disease (ie, early or late).
Early symptoms of classic hookworm disease
During the first 1-2 weeks after a cutaneous infection, hookworm produces a local irritation at the site of infection, termed ground itch or dew itch. [17] An intensely pruritic, erythematous, or vesicular rash appears, usually on the feet or hands; its severity is generally proportionate to the number of infecting larvae. This rash should be distinguished from a creeping eruption due to skin migration of the cat or dog hookworm A braziliense.
Cough and wheezing can occur about 1 week after exposure as a consequence of larval migration through the lungs. Pulmonary symptoms are uncommon and usually mild, except in severe infections. In rare cases, severe infections may give rise to Löffler syndrome, characterized by paroxysmal attacks of cough, dyspnea, pleurisy, little or no fever, and eosinophilic pulmonary infiltrates that last several weeks after the initial infection. [26]
Migration of the worms into the gastrointestinal (GI) tract may cause GI discomfort secondary to irritation. As the worms mature in the jejunum, patients may experience diarrhea, vague abdominal pain, colic, flatulence, nausea, or anorexia. These symptoms are more common with initial exposures than with subsequent exposure and typically peak between 30 and 45 days after infection.
In people who have been infected with a large burden of A duodenale through oral ingestion, Wakana syndrome may occur. This syndrome resembles an immediate-type hypersensitivity reaction and is characterized by pharyngeal itching, hoarseness, nausea, vomiting, cough, dyspnea, and eosinophilia. [26]
Later symptoms of classic hookworm disease
Mild hookworm infections are often asymptomatic. Moderate-to-heavy infections cause significant blood loss, which may manifest as melena. Once iron reserves are exhausted, anemia develops. A large worm burden and a history of poor iron intake increase the likelihood of significant anemia.
Patients with severe iron-deficiency anemia may present with lassitude, headache, palpitations, exertional dyspnea, syncope, or edema. They may also have a history of perverted taste and pica. In rare cases, anemia may provoke ischemic symptoms such as angina or claudication.
Deficits in physical and intellectual growth can occur due to anemia and protein deficiency; these deficits may be irreversible when they develop during childhood.
Cutaneous larva migrans
Infection with zoonotic hookworms, especially A. braziliense, can progress with a lateral skin migration of larvae that results in the characteristic tracts of cutaneous larva migrans (creeping eruption). [34] This is to be distinguished from the ground itch noted in classic hookworm disease.
Eosinophilic enteritis
Eosinophilic enteritis is characterized by repeated episodes of abdominal pain in approximately 97% of affected individuals. These episodes typically occur with increasing severity and are associated with peripheral eosinophilia in almost 100% of patients and with leukocytosis in approximately 75% of patients. Extreme cases may mimic appendicitis or intestinal perforation.
Physical Examination
Skin and pulmonary findings are minimal. Physical findings in the early (larval migration) stage of the disease differ from those in the late (established GI infection) stage.
Early signs of classic hookworm disease
An erythematous, pruritic, papulovesicular rash develops at the site of initial infection and may persist for 1-2 weeks after initial infection. Intense scratching may lead to a secondary bacterial infection, which is quite common.
When the worms break through from the venous circulation into the pulmonary air spaces, cough, fever, and a reactive bronchoconstriction may be observed, with wheezing heard on auscultation.
During the period of intestinal involvement, abdominal examination may reveal midepigastric pain on palpation. Stools may be bloody or melanotic.
Later signs of classic hookworm disease
Signs of iron-deficiency anemia are often insensitive. Patients may exhibit pallor, chlorosis (greenish-yellow skin discoloration), hypothermia, spooning nails, tachycardia, or signs of high-output cardiac failure.
Hypoproteinemia may lead to anasarca and peripheral edema. [10] Poor skin texture, edema, and susceptibility to cutaneous infection suggest possible malnutrition. Stunted growth may be observed in children with severe infection. [35]
Cutaneous larva migrans
Cutaneous larva migrans manifests as pathognomonic, raised serpiginous tracts (creeping eruptions) with surrounding erythema that may last as long as 1 month if untreated. Lesions are most commonly seen on lower extremities but may be limited to the trunk or upper extremities, depending on the site at which the infective larvae entered the body. [36]
Cutaneous larva migrans. Courtesy of Wikipedia [WeisSagung, https://en.wikipedia.org/wiki/Cutaneous_larva_migrans].
Complications
Intense exposure resulting in heavy parasitism can produce acute gastrointestinal hemorrhage, severe acute anemia, and congestive heart failure. An early example was an epidemic called “miner’s anemia” striking Italian laborers building the alpine Saint Gotthard railway tunnel in 1880. Today, this occurs most often in epidemics associated with breakdowns in sanitation as a result of war or famine but can also occur in especially burdened individuals from endemic areas. [25]
More commonly, children with chronic infection perform poorly in school and have decreased productivity. [37] The etiology of this cognitive impairment is probably multifactorial, secondary to both chronic iron-deficiency anemia and protein deficiency, as well as missed learning opportunities.
Children with chronic infection may also have linear growth retardation (stunted growth). [35] In one study, children with helminthiasis (including infection caused by hookworms and other helminths) and anemia were 8.7 times more likely to have stunted growth and 4.3 times more likely to be underweight than children without anemia and infection. [38]
In rare cases, neonatal infection with A duodenale contracted through breastfeeding may lead to fulminant GI hemorrhage.
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Adult hookworm attached to duodenal mucosa.
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Hookworm filariform larva. Courtesy of Division of Parasitic Diseases, Centers for Disease Control and Prevention (CDC).
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Adult Ancylostoma duodenale worm. Anterior end with mouth parts visible. Courtesy of Patrick W Hickey, MD.
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Adult Necator americanus worm. Anterior end with mouth parts visible. Courtesy of Patrick W Hickey, MD.
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Hookworm eggs examined on wet mount. Eggs of Ancylostoma duodenale and Necator americanus cannot be distinguished morphologically. Courtesy of Division of Parasitic Diseases, Centers for Disease Control and Prevention (CDC).
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Hookworm rhabditiform larva (wet preparation). Courtesy of Division of Parasitic Diseases, Centers for Disease Control and Prevention (CDC).
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Life cycle of hookworm. Courtesy of the Centers for Disease Control and Prevention (CDC) [https://www.cdc.gov/parasites/hookworm/biology.html].
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Hookworm egg in an unstained wet mount at 400x magnification. Courtesy of the Centers for Disease Control and Prevention (CDC) [https://www.cdc.gov/dpdx/hookworm/].
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Hookworm rhabditiform larva. Courtesy of the Centers for Disease Control and Prevention (CDC) [https://www.cdc.gov/dpdx/hookworm/].
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Side-by-side image of the mouth parts of each species of human-infecting hookworm. Courtesy of the Centers for Disease Control and Prevention (CDC) [https://www.cdc.gov/parasites/hookworm/biology.html].
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Cutaneous larva migrans. Courtesy of Wikipedia [WeisSagung, https://en.wikipedia.org/wiki/Cutaneous_larva_migrans].
Tables
Intensity |
Eggs per gram of feces |
Mild |
< 1,999 |
Moderate |
2,000-3,999 |
Heavy |
>4,000 |
Drug |
Adults |
Children (>24 months) |
Albendazole (preferred)* |
|
|
Mebendazole |
|
|
Pyrantel pamoate |
|
|
Thiabendazole |
|
|
