Amoebiasis

Amoebiasis, also known as amebiasis or amoebic dysentery, is an infection caused by the protozoan parasite Entamoeba histolytica. This unicellular organism primarily affects the human gastrointestinal tract, particularly the large intestine, but can spread to other parts of the body such as the liver, lungs, or brain.

Entamoeba histolytica life cycle-en

Epidemiology

Amoebiasis of intestine, 20x

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Tissue damage caused by E. histolytica is a result of three main events, host cell death, inflammation, and parasite invasion

Amoebiasis is a global health concern, particularly prevalent in tropical regions with poor sanitary conditions. It is estimated to affect approximately 50 million people worldwide annually, causing 40,000 to 100,000 deaths each year.

Transmission

E. histolytica cyst

The transmission of E. histolytica occurs primarily through ingestion of contaminated water or food containing cysts (dormant, resistant form of the parasite). It can also occur through direct contact, including sexual contact particularly involving anal intercourse.

Clinical Manifestation

Amoebiasis manifests in two forms: intestinal amoebiasis and extraintestinal amoebiasis. The majority of infected individuals are asymptomatic carriers, but symptoms can occur in some cases.

Intestinal Amoebiasis

In intestinal amoebiasis, symptoms may range from mild discomfort to severe dysentery characterized by abdominal pain, diarrhea, and bloody stools. Other symptoms can include fatigue, weight loss, and excessive gas.

Extraintestinal Amoebiasis

In extraintestinal amoebiasis, the most common form is amoebic liver abscess, presenting with fever, right upper quadrant pain, and hepatomegaly. Less commonly, it can affect the lungs, brain, or other organs.

Diagnosis

The diagnosis of amoebiasis is made through stool microscopy, antigen detection tests, and PCR. Serological tests may be used to detect extraintestinal disease. Imaging studies like ultrasound or CT scan can help identify amoebic liver abscesses.

Treatment

Treatment involves pharmacotherapy with amoebicidal medications such as metronidazole or tinidazole, followed by luminal agents like diloxanide furoate or paromomycin to eliminate any remaining intestinal cysts. In cases of amoebic liver abscess, drainage might be required if the abscess is large or does not respond to medical treatment.

Prevention

Prevention strategies for amoebiasis center around improving sanitation and water quality, including proper disposal of human feces, protection of water supplies from contamination, and appropriate hand hygiene practices. In endemic areas, health education about the risks of amoebiasis and protective measures is crucial.

References

• [1] Stanley SL Jr. (2003). Amoebiasis. The Lancet, 361(9362), 1025-1034.
• [2] Shirley DT, Farr L, Watanabe K, Moonah S. (2018). A Review of the Global Burden, New Diagnostics, and Current Therapeutics for Amebiasis. Open Forum Infectious Diseases, 5(7), ofy161.
• [3] Petri WA Jr, Haque R, Lyerly D, Vines RR. (2000). Estimating the impact of amebiasis on health. Parasitology Today, 16(8), 320-321.
• [4] Haque R, Huston CD, Hughes M, Houpt E, Petri WA Jr. (2003). Amebiasis. The New England Journal of Medicine, 348(16), 1565-1573.

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