Cystoisospora belli

Cystoisosporiasis is a human intestinal disease caused by the protozoan parasite Cystoisospora belli. It is an obligate intracellular parasite that invades intestinal epithelial cells. It causes a self-limited or prolonged diarrhea, depending on the host’s immune status. C. belli is cosmopolitan, but more common in the tropics and subtropics. The parasite can be spread by ingesting contaminated food or water. C. belli oocysts are ellipsoid and approximately 25 μm to 33 μm by 10 μm to 20 μm and contain two sporocysts, which contain 4 sporozoites each. Feces are the common way of immature form of the parasite release. The parasite, usually needs between 1 or 2 days in the environment (outside of host) to performe the adequate maturation steps to be able infect further subjects. Watery diarrhea is the most common symptom. Other symptoms can include cramps, abdominal pain, dehydration, loss of appetite, nausea, fever and vomiting. Diagnosis is achieved by oocysts observation via microscopic stool examination. Enhanced detection is obtained by staining stool samples via modified acid-fast stain, modified safranin stain or by fluorescence microscopy. Molecular diagnostic methods have the advantage of high sensibility for an early detection of these coccidian parasites in stool samples. If untreated, immunocompromised individuals may increase the risk for prolonged and severe illness. The usual treatment is with trimethoprim-sulfamethoxazole. Cystoisosporiasis can be prevented with adequate sanitation, measures to protect food and water supplies, and increased public awareness of the means of transmission.

Keywords: C. belli life cycle, Coccidia, Cystoisospora belli, Intracellular parasite, Parasitic infection, Protozoa.