Amoebiasis due to Entamoeba histolytica

Amoebiasis due to Entamoeba histolytica is an infectious parasitic disease caused by the protozoan parasite Entamoeba histolytica. It is not a genetic disorder but rather an acquired infection transmitted through the fecal-oral route, typically via contaminated water or food. The disease is most prevalent in tropical and subtropical regions with poor sanitation. Approximately 90% of infections are asymptomatic, but the parasite can cause significant illness when it invades the intestinal wall or spreads to other organs. The disease primarily affects the gastrointestinal system, most commonly the colon, where it causes amoebic colitis characterized by bloody diarrhea (amoebic dysentery), abdominal pain, cramping, and tenderness. The parasite can erode through the intestinal mucosa, forming characteristic flask-shaped ulcers. In more severe cases, Entamoeba histolytica can spread hematogenously to the liver, causing amoebic liver abscess, which presents with right upper quadrant pain, fever, and hepatomegaly. Less commonly, the infection can disseminate to the lungs, brain, or other organs, leading to potentially life-threatening complications including amoebic lung abscess, cerebral amoebiasis, or cutaneous amoebiasis. Treatment depends on the clinical presentation. Invasive amoebiasis (symptomatic intestinal disease or extraintestinal disease) is treated with metronidazole or tinidazole as tissue-active agents, followed by a luminal agent such as paromomycin or diloxanide furoate to eliminate cysts remaining in the intestine. Asymptomatic carriers harboring cysts should also be treated with a luminal agent to prevent transmission and potential future invasive disease. Large liver abscesses may occasionally require percutaneous drainage. With appropriate treatment, the prognosis is generally good, though fulminant colitis and ruptured liver abscess carry significant mortality. Prevention relies on improved sanitation, safe water supply, and proper food hygiene.

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