Multiple Cryptosporidium serpentis oocyst isolates from captive snakes are not transmissible to amphibians.

Viable Cryptosporidium serpentis oocysts originating from 6 captive snakes were gastrically delivered to 12 Cryptosporidium-free African clawed frogs and 9 tadpoles and 3 recently metamorphosed adults of Cryptosporidium-free wood frogs. On days 7 and 14 postinoculation, no life-cycle stage of Cryptosporidium was observed in any of the histological sections of stomach, jejunum, ileum, cloaca, and cecum. However, viable inoculum-derived C. serpentis oocysts were recovered from the water in which the amphibians were kept. Amphibians may disseminate C. serpentis oocysts in the natural habitat.