Amebiasis

Amebiasis is a common cause of diarrhea in infants in low-income countries and an emerging sexually transmitted infection in some developed countries. Amebiasis also causes colitis that can present with diarrhea and/or dysentery that can be acute or last more than 1 week. Abdominal tenderness and weight loss are common with amebic colitis. 

Amebic liver abscess presents with right upper quadrant pain. May not present with diarrhea, but will usually have a preceding history of diarrhea.

Rare cause of brain abscess.

Most patients will have traveled to or resided in an endemic area in the 12 months preceding presentation. Oral-anal sexual contact is a risk factor for sexual transmission.

Diagnosis is confirmed by detection of Entamoeba histolytica antigen or DNA in stool or antibodies against the parasite in serum.

Treatment is with nitroimidazoles (including metronidazole or tinidazole) followed by luminal agents such as paromomycin or diloxanide furoate to prevent relapse. Reinfection is common in endemic regions; patients should be counselled on how to reduce the risk of reinfection.

Amebiasis is caused by the parasite Entamoeba histolytica. It causes diarrhea and colitis. Spread of infection from the intestine can result in liver abscess (via haematogenous dissemination). Extension from liver abscess can lead to pleural and pericardial effusion. Rarely, brain abscess may occur[1]Haque R, Huston CD, Hughes M, et al. Amebiasis. New Engl J Med. 2003;348:1565-1573. http://www.ncbi.nlm.nih.gov/pubmed/12700377?tool=bestpractice.com [2]Petri WA Jr, Singh U. Diagnosis and management of amebiasis. Clin Infect Dis. 1999;29:1117-1125. http://www.ncbi.nlm.nih.gov/pubmed/10524950?tool=bestpractice.com [3]Solaymani-Mohammadi S, Lam M, Zunt JR. Entamoeba histolytica encephalitis diagnosed by polymerase chain reaction of cerebrospinal fluid. Trans R Soc Trop Med Hyg. 2007;101:311-313. http://www.ncbi.nlm.nih.gov/pubmed/16930651?tool=bestpractice.com [4]Watanabe K. Amebiasis. In: Rakel RE, ed. Conn's current therapy 2019. New York, NY: W.B. Saunders; 2019.[5]Stanley SL Jr. Amoebiasis. Lancet. 2003;361:1025-1034. http://www.ncbi.nlm.nih.gov/pubmed/12660071?tool=bestpractice.com [6]Diamond LS, Clark CG. A redescription of Entamoeba histolytica Schaudinn, 1903 (amended Walker, 1911) separating it from Entamoeba dispar Brumpt, 1925. J Eukaryot Microbiol. 1993;40:340-344. http://www.ncbi.nlm.nih.gov/pubmed/8508172?tool=bestpractice.com