A review of coccidiosis in Old World camels

Domesticated Old World camels (Camelus dromedarius and C. bactrianus) are important for the economy of several countries in Asia, Africa, and the Arabian Peninsula, and coccidiosis is important as a cause of mortality in juvenile camels. There is confusion concerning the species of coccidian parasites in camels and their life cycles. The objective of the present paper is to review biology of the Eimeria and Cystoisospora species in camels. The following conclusions were drawn. Although five species of Eimeria; E. cameli, E. rajasthani, E. dromedarii, E. bactriani, and E. pellerdyi were named from camels, only E. cameli, E. rajasthani, E. dromedarii have been consistently found in numerous surveys and they are morphologically distinct. We consider E. pellerdyi and E. bacterini as species enquirende/ not valid. E. cameli oocysts are distinctive, dark brown and up to 108 μm long. Its gametogonic stages and oocysts are present in the lamina propria of small intestines; only sexual stages have been confirmed. The remaining species of Eimeria (E. rajasthani and E. dromedarii) in camels are <40 μm long and their endogenous stages are unknown. There is one valid species of Cystoisospora, C. orlovi in camels and is associated with severe disease in young camels, both pastoral and stall fed camels. Camels as young as nine days old can develop severe diarrhea and can die before oocysts are detected in feces. Lesions and endogenous stages are confined to the large intestine. The main lesion is hemorrhagic, diphtheroid to hemorrhagic colitis-associated with sexual stages; asexual stages are unknown. Oocysts are rarely excreted by adult camels, and in low numbers. Therefore, infection in very young camels remains unexplained.