Microscopic study on Sarcocystis moulei from sheep and goats in Saudi Arabia.

The present investigation revealed that the role of natural infection with Sarcocystis in sheep was 84% in Niemy, 76% in Najdy, 89% in Sawakny sheep and 77% in goats slaughtered in Riyadh, Saudi Arabia. The distribution of infection among the examined organs was varied from the sheep strain to goats. Recorded muscle cysts were macroscopic 8-18% (mean 13.5%) and microscopic 73-85% (mean 79%). Macroscopic cysts were usually detected on the oesophagus. EM showed an ultrastructural similarities in the cyst walls and their parasite contents (metrocytes and merozoites) for all macroscopic cysts examined from sheep and goats. These were also enclosed by a secondary cyst wall. The primary cyst wall had many cauliflower-like protrusions supported by many fibellar structures, while the ground substance underneath them contained many dark, dense granules and usually extended into the cyst cavity dividing it into many compartments containing the parasites. The cyst parasites were the peripheral globular to spherical metrocytes, which were divided by endodyogeny and the central banana-shaped merozoites. Both metrocytes and merozoites had all characteristics of the Apicomplexa. Experimental transmission of Sarcocystis to the definitive host, revealed that kittens were the only suitable final host. Thus, gamogony and zygote formation (fertilization) occurred 2-8 days post infection (p.i.) while sporulation took place within this final host 13-15 days p.i., where sporocysts were passed within faeces of infected kittens at that time. Also, the study indicated that the prepatent period was 13-15 days, while the patent period was 37-42 days.