EXPERIMENTAL TRANSMISSION OF CRYPTOSPORIDIUM OOCYST ISOLATES FROM MAMMALS, BIRDS AND REPTILES TO CAPTIVE SNAKES

Groups of four to five, 3-month-old rat snakes (Elaphe obsoleta) were separately gastrically inoculated with 2.0 x 10(6) viable oocysts of C ryptosporidium muris (mice and calves), C. muris-like (Bactrian camels ), C. wrairi (guinea pigs), C. baileyi (chickens), C. meleagridis (tur keys), Cryptosporidium sp. (turtles, tortoises, chameleons and lizards ) and C. serpentis from clinically (fatal case) and subclinically infe cted snakes. None of the snakes inoculated with oocysts originating fr om homothermous vertebrates developed infection as determined by histo logy and serology, whereas all snakes challenged with reptilian oocyst isolates were infected with Cryptosporidium on weeks 6 and 10 post in oculation (PI). On week 10 PI, the snakes displayed mild to severe, mu ltifocal to widespread, thinning and disorganization of gastric epithe lium and nine out of twelve snakes infected by oocysts originating fro m reptiles other than snakes displayed severe gastric hyperplasia. Thr ee out of ten snakes infected by oocysts originating from snakes had E LISA-detectable Cryptosporidium-specific antibody (Ab) titers on week 6 PI; all snakes were Cryptosporidium-seroconverted on week 10 PI and their serum Ab titer significantly increased. The study demonstrated t hat Cryptosporidium infections in snakes maintained on the diet of rod ents or birds cannot be initiated via ingestion of an infected food it em; however, snakes can void ingested oocysts. Lack of host specificit y among reptiles to this pathogen, demonstrated for the first time in the present study, indicates that snake-attributed C. serpentis is not distinct from Cryptosporidium sp. infecting reptiles other than snake s, and that clinical manifestations and virulence of Cryptosporidium i n snakes is modulated by the species of the host. Housing of snakes wi th other reptiles can enhance transmission of Cryptosporidium to snake s, and therefore should be avoided. (C) Inra/Elsevier, Paris.