Early development of the coccidium Sarcocystis muriviperae Matuschka, Heydom, Mehlhom, Abd-Al-Aal, Diesing et Bichler, 1987 is described from experimentally infected white mice fed sporocysts from naturally infected Vipera palaestinae and Coluber jugularis. Although the course of infection was similar, mice infected with the sporocysts from the first host survived an inoculum of up to 200,000 sporocysts, while others infected with the second, succumbed to inocula exceeding 40,000 sporocysts in 7-10 days post infection (p,i,). Histological and ultrastructural studies revealed merogony in the hepatocytes during days 7-10 p.i. and onset of sarcocyst development by days 19-21 p.i. The livers of infected mice are grossly enlarged and of a mottled whitish colour due to severe neutrophil inflammatory infiltration, apparently stimulated by host cell residues or from defunct disaggregating meronts at the end of the merogony cycle. Early sarcocysts undergo a further division by endopolygeny before proceeding to division by endodyogeny.
The ultrastructure of the endogenous stages - merozoites, microgamonts, macrogamonts and oocysts, of Sarcocystis muriviperae from the snakes Vipera palaestinae and Coluber jugularis is described. Snakes were infected via white mice fed on sporocysts obtained from naturally infected snakes of the same species. Snakes examined 4 days post-infection contained only young and premature gamonts. Infection in snakes sacrificed on day 7 post-infection consisted predominantly of mature microgamonts and macrogamonts; snakes examined on day 10 post-infection revealed only oocysts. The fine structure of the endogenous stages from the two snakes, including size and contents of the wall-forming bodies, was identical, confirming their suggested conspecificity. Observed endogenous stages also conformed in their major details with the same developmental stages of other Sarcocystis species studied from other snakes and mammalian definitive hosts and from in vitro culture. However, they differed from the latter in size and contents of the wall-forming bodies. The observed fertilization process was reminiscent of that described earlier in S. bovicanis.