Colites parasitaires

Parasitic colonic diseases refer to a polymorphic concept; they may present an acute or a chronic expression, often non symptomatic, and they include the amoebosis and the schistosomiasis which are dominant in tropical countries. The colon may be concerned by cosmopolitan or exotic parasites with highly variable incidence and prevalence, simply in transit, or as usual hosts, or trapped in the colonic wall. The consequences range from the epiphenomenona to anatomo-clinical manifestations potentially serious and life threatening. The pathophysiology results from interactions between the host, the external environment and the parasite; the parasite aggression involves immunomediated inflammatory or parasitic enzyme related phenomena. Three groups of parasitic colitis have been identified, with a distinct identity: the common parasitic tropical colitis, the parasitic colitis favoured by immunodepression, and the specific parasitic colonic deadlock with colic tropism. The diagnosis focuses on the anamnesis and seeks for the involved parasite identification by stool analysis when possible, and by the colorectal endoscopy which supports the anatomo-clinical diagnosis. As for the treatment, three antiparasitic classes (5-nitro-imidazole agents, benzimidazole agents, and praziquantel), and more recent molecules (ivermectine, nitazoxanide) are available; less frequently, surgery is indicated, for the complicated forms or in case of unascertained diagnosis.