Intestinal protozoan infections (parasitic diarrhea)

The main protozoan intestinal amebiasis are (Entamoeba histolytica), giardiasis (Giardia lamblia), Cryptosporidiosis(Cryptosporidium sp) cyclosporosis (Cyclospora cayetanensis) and isosporiasis (Isospora belli).

Intestinal protozoa are transmitted by faecal-oral route (dirty hands, ingestion of water or food contaminated with feces) and individual case managers and diarrhea epidemic.

Intestinal protozoan infectionsClinical signs:

– Amoebiasis is bloody diarrhea.

– The clinical giardiasis, cryptosporidiosis, and Cyclosporiasis isosporiasis has many similarities:

• Diarrhea is rarely abundant and usually self-limited, except in children but especially in patients with advanced stage of infection with HIV (<200 CD4). In these patients, the diarrhea may be abundant, intermittent or chronic and cause malabsorption with significant weight loss (or weight stagnation in children) or severe dehydration.

• The stools are usually aqueous but steatorrhoea (pale stools, large, fat) is possible in case of high fat malabsorption;stool may also contain mucus.

• Diarrhea is associated with banal digestive disorders (distension and abdominal cramps, flatulence, nausea, anorexia) but patients have little or no fever.


The definitive diagnosis is based on the detection of the parasite as cysts or trophozoites (giardia) or oocysts (Cryptosporidium, Cyclospora, Isospora) in stool (2-3 samples, 2 or 3 days apart because parasites are excreted in feces intermittently).


– Correct dehydration if present.

– If the causative agent was identified in stool:


– If a reliable examination can be achieved: it is impossible to distinguish clinically parasitic diarrhea them nor non parasitic diarrhea. Empirical treatment (sequentially or simultaneously combining metronidazole or tinidazole and cotrimoxazole as above) can be tried in cases of prolonged diarrhea or steatorrhea. In patients infected with HIV.

– The cryptosporidiosis, cyclosporoses isosporoses and being opportunistic infections in patients in advanced stages of HIV infection, the most effective response is to put on antiretroviral treatment, but the risk of dehydration / death remains high as immunity is not sufficiently restored.