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Most infected patients have no symptoms but pass cysts in their feces. Sexual transmission occurs by oral-anal contact. Patients with amebic dysentery have high fever with abdominal cramping. Tender hepatomegaly is common, and patients may also have anemia, weight loss, and amebomas (tumor-like masses of the colon). The organisms may invade any organ, but liver abscesses are the most common complication. [Merck Manual, p. 1565] The laboratory may fail to detect pus in stool specimens because the trophozoites lyse leukocytes. Lactoferrin tests can detect inflammatory diarrhea in such cases when fecal leukocytes are absent. [Wilson, p. 262] Liver abscesses may be associated with leukocytosis. [Guerrant, p. 1465] Patients with amebic dysentery have fever, diarrhea, and blood in the stools. Complications include amebomas, liver abscesses, and rarely, lung and brain abscesses. Families with poor sanitation are at increased risk for E. histolytica infection. Transmission occurs by ingestion of water or food contaminated with feces containing cysts, which are relatively resistant to chlorine water treatment. [CCDM, p. 11-15] About 10% of the world's population is infected with E. histolytica. About 90% of infected people are asymptomatic, but the disease causes 50,000-100,000 deaths per year. Pleuropulmonary manifestations of liver abscesses include effusions, consolidation, cough, and pleuritic pain. About 80-90% of patients with acute amebic dysentery will test positive after the examination of 3 fresh stools for ova or trophozoites. After 7 days, serology is positive in about 60-90% of cases. About 90% of patients with liver abscesses have positive serology. Most laboratories cannot distinguish E. histolytica from the harmless commensal, E. dispar. [Lexi-ID, p. 124-5] |
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