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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
CLINICAL MANIFESTATIONS: Patients with hookworm infection most
often are asymptomatic; however, chronic hookworm infection
is a common cause of 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. After oral ingestion
of infectious
Ancylostoma duodenale larvae, disease can manifest
with pharyngeal itching, hoarseness, nausea, and vomiting shortly
after ingestion. Colicky abdominal pain, nausea, and/or diarrhea
and marked eosinophilia can develop 4 to 6 weeks after exposure.
ETIOLOGY: Necator americanus is the major cause of hookworm
infection worldwide, although
A duodenale is also an important
hookworm in some regions. Mixed infections are common. Both
are roundworms (nematodes) with similar life cycles.
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 Europe, the Mediterranean region,
northern Asia, and the west coast of South America.
Necator americanus is predominant in the Western hemisphere, sub-Saharan
Africa, Southeast Asia, and a
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Related text in Red Book:
- Drugs for Parasitic Infections
Red Book
2006: 790-820.
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