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Article Type

Original Study

Abstract

Objectives To study the experimental induction of Sarcocystis spp. infection in rats and to identify the Sarcocystis spp. through parasitological, histopathological, and electron microscopic studies. Background Sarcocystis spp. is an obligatory intracellular parasite of humans and animals. The genus Sarcocystis comprises about 130 species with differences in their life cycle and pathogenicity and represents important members of the cyst-forming coccidian. Materials and methods Macroscopic sarcocysts were isolated manually from 80 selected buffaloes that were slaughtered in Sirs Ellian City, Menoufia Governorate. The extracted sarcocysts samples were used to infect rats and were also preserved and prepared for species identification by histopathological and electron microscopic studies. Sixty rats were classified into six groups, with 10 rats/group (one control not infected and five infected groups), according to the date they were killed. Every rat was infected by feeding on 10 g of sarcocysts containing about 20 visible intact sarcocysts. Stool examination every day until the time they were killed and histopathological and electron microscopic studies for intestinal tissue specimens were performed. Results Histological and electron microscopic identification of sarcocyst specimens extracted from infected buffaloes revealed Sarcocystis fusiformis(thick wall 3.5 μm and cauliflower villar protrusions). A parasitological study of the infected rats' stools revealed excretion of Sarcocystis sporocysts (measuring 9–11 × 7 μm) in 40% of the infected rats at 1 week postinfection (group IV), in 60% at 2 weeks postinfection (group V), and continuous shedding of sporulated oocysts occurred in 40% of the rats at 1 month postinfection (group VI). Histopathological and transmission electron microscope examination of the infected rats' intestinal tissues revealed dividing oocysts (16 × 12.5 μm) with two sporocysts (11 × 7 μm) in the lamina propria of the small intestine in group V. Conclusion Rats could be considered as an experimental definitive host for S. fusiformis and could play a role in Sarcocystis spp. transmission to domestic animals.

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