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Amebiasis
Description
Amebiasis is caused by the protozoan parasite Entamoeba
histolytica. Infection is acquired by the fecal-oral route,
either by person-to-person contact or indirectly by eating or drinking
fecally contaminated food or water.
Occurrence
Amebiasis occurs worldwide, especially in regions
with poor sanitation.
Risk for Travelers
For travelers to low-income countries, risk for
infection is highest for those who live in or visit rural areas,
spend time in backcountry areas, or eat or drink in settings of poor
sanitation.
Clinical Presentation
The incubation period is commonly 2–4 weeks
but ranges from a few days to years. The clinical spectrum of intestinal
amebiasis ranges from asymptomatic infection to fulminant colitis. Entamoeba
dispar, which is nonpathogenic, cannot be distinguished from
the pathogen E. histolytica by routine microscopy; however,
an enzyme immunoassay kit for distinguishing the two organisms is
commercially, but not widely available. In persons infected with E.
histolytica who are symptomatic, the most common symptom is diarrhea.
The diarrhea can evolve to painful, bloody bowel movements, with
or without fever (amebic dysentery). Occasionally, amebiasis causes
disease outside the intestinal tract, most notably in the liver (amebic
liver abscess).
Prevention
No vaccine is available. Travelers to low-income
countries should be advised to follow the precautions detailed in
the section Risks
from Food and Drink and avoid sexual practices
that may lead to fecal-oral transmission.
Treatment
Travelers may be advised to consult with an infectious
disease specialist to ensure proper diagnosis and treatment. Iodoquinol
or paromomycin are the drugs of choice for asymptomatic but proven E.
histolytica infections. For mild or moderate to severe intestinal
disease and extraintestinal disease (e.g., hepatic abscess), treatment
with metronidazole or tinidazole (not yet available in the United
States) should be immediately followed by treatment with paromomycin
or iodoquinol.
— Barbara
Herwaldt, Jeff Jones
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