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Section 3. Summaries of Infectious Diseases

Hookworm Infections

(Ancylostoma duodenale and Necator americanus)

Clinical Manifestations
Etiology
Epidemiology
Diagnostic Tests
Treatment
Isolation of the Hospitalized Patient
Control Measures

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CLINICAL MANIFESTATIONS

Patients with hookworm infection often are asymptomatic; however, chronic hookworm infection is a common cause of moderate and severe hypochromic microcytic anemia in people living in tropical developing countries, and heavy infection can cause hypoproteinemia with edema. Chronic hookworm infection in children may lead to physical growth delay, deficits in cognition, and developmental delay. After contact with contaminated soil, initial skin penetration of larvae, usually involving the feet, can cause a stinging or burning sensation followed by pruritus and a papulovesicular rash that may persist for 1 to 2 weeks. Pneumonitis associated with migrating larvae is uncommon and usually mild, except in heavy infections. Colicky abdominal pain, nausea, and/or diarrhea and marked eosinophilia can develop 4 to 6 weeks after exposure. Blood loss secondary to hookworm infection develops 10 to 12 weeks after infection and symptoms related to serious iron-deficiency anemia can develop in long-standing moderate or heavy hookworm infections. After oral ingestion of infectious Ancylostoma duodenale larvae, disease can manifest with pharyngeal itching, hoarseness, nausea, and vomiting shortly after ingestion.


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ETIOLOGY

Necator americanus is the major cause of hookworm infection worldwide, although A duodenale also is an important hookworm in some regions. Mixed infections are common. Both are roundworms (nematodes) with similar life cycles.


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EPIDEMIOLOGY

Humans are the only reservoir. Hookworms are prominent in rural, tropical, and subtropical areas where soil contamination with human feces is common. Although both hookworm species are equally prevalent in many areas, A duodenale is the predominant species in the Mediterranean region, northern Asia, and the west coast of South America. N americanus is predominant in the Western hemisphere, sub-Saharan Africa, Southeast Asia, . . . [Go to Full Text]


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