Cystoisospora orlovi (Eimeriorina: Sarcocystidae)-A little known coccidian of the old world camelids

Based on the morphology of its oocysts Cystoisospora orlovi was described in camel calves in Kazakhstan in 1950. Over decades C. orlovi was considered a pseudo-parasite until alterations caused by this parasite in the colon of dromedary calves were described. During an observation period of 150 months (January 2005-June 2017), 85 cases of coccidiosis due to C. orlovi were observed in 72 camel calves and 13 adult dromedaries in Dubai (United Arab Emirates). Most of the cases in camel calves were seen between the months of December to May in an age group of up to 35 days while the majority of cases in adult camels occurred in summer. Contrary to Eimeria infections in camelids, C. orlovi causes a diphtheroid colitis with multiple erosions of the mucosa of the large intestine. Most of the cases were diagnosed post mortem. Only 11 camels in which the parasite was diagnosed intra vitam survived. The sporadic occurrence of cystoisosporosis in single suckling calves suggests a vertical transmission of the parasite from mother to calf.