Extraintestinal Development ofCaryospora simplex(Apicomplexa: Eimeriidae) in Experimentally Infected Mice,Mus musculus1

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Abstract
Developmental stages of C. simplex were found in connective tissue of the cheek, tongue and nose of Swiss-Webster and C57 BL/6 mice (M. musculus) from 8 through 70 days after oral inoculation with 50,000 or 250,000 oocysts, or 60,000 free sporocysts of the same species obtained from an Ottoman viper, Vipera xanthina xanthina. The earliest developmental stages were seen on day 8 post-inoculation (PI) and consisted of 2 types of meronts and gamonts (undifferentiated sexual stages). Gamonts, microgametocytes, macrogametes, and unsporulated oocysts were found on days 10 and 12 PI. Fully sporulated, thin-walled oocysts containing 8 sporozoites surrounded by a thin sporocyst membrane were first seen 12 days PI. Monozoic cysts (caryocysts) were first seen 12 days PI and appeared fully viable throughout the duration of the study, 70 days PI. Four mice injected i.p. with 150,000 free sporozoites and killed 12 days PI contained unsporulated and sporulated oocysts in connective tissues of the cheek, tongue and nose, suggesting that sporozoites may be carried to the site of infection via the lymphatic/circulatory system. Four cotton rats, Sigmodon hispidus, inoculated orally with 250,000 oocysts all had unsporulated and sporulated oocysts of C. simplex in connective tissue of the cheek, tongue and nose when killed on day 12 PI, indicating extraintestinal development in the secondary host is not species specific. this is the 1st report of a heteroxenous coccidium with both asexual and sexual development in the primary (predator) and secondary (prey) hosts.