Balantidium Coli Colitis Revealing a Common Variable Immunodeficiency: A Case Report

Balantidium Coli is a large protozoan parasite, measuring up to 150 micrometers, initially identified in 1857 and later renamed in 1861-1862. It is an animal parasite, with its primary reservoir being pigs (domestic pigs/wild boars), but it can also be found in other animal species such as dogs, cats, hyenas, buffaloes, camels, monkeys, and others. Humans are an accidental host, as they represent a dead-end in the parasitic life cycle. Infection by this parasite is typically asymptomatic or presents with mild symptoms. It becomes pathogenic only in cases of primary or secondary immunodeficiency, where it typically manifests as colitis; however, urinary tract involvement is also possible. In our case, Balantidium Coli infection presented multiple challenges. It is not a well-known parasite in our region, particularly since pig farming is not practiced in Morocco. The parasite was found in both the urine and stool of the patient, who exhibited clear signs of infection which is not usual with this parasite. This led to the "late" discovery of Common Variable Immunodeficiency (CVID) in the patient, a primary immunodeficiency typically diagnosed before the age of 4 and characterized by a deficiency in immunoglobulin production, particularly affecting the IgA and IgG fractions.