CYCLIC TRANSMISSION OF SARCOCYSTIS-GERBILLIECHIS N-SP BY THE ARABIAN SAW-SCALED VIPER, ECHIS-COLORATUS, TO RODENTS OF THE SUBFAMILY GERBILLINAE

Infection experiments with rodents and snakes were performed to elucid ate the life cycle of a Sarcocystis isolate found in an Arabian saw-sc aled viper, Echis coloratus. Oocysts in feces of the naturally infecte d and of 2 experimentally infected Arabian saw-scaled vipers were alre ady sporulated and contained 2 sporocysts each, measuring 12.7 (12.3-1 3.3) mu m x 11.0 (10.7-11.4) mu m. After oral inoculation of various r odent species with these sporocysts, sarcocysts developed in the esoph agus and skeletal muscles of gerbils and related genera. Mature sarcoc ysts were filiform in shape and reached a maximum length of 11.7 mm af ter 5 mo postinoculation (PI), whereas the width did not exceed 190 mu m. The primary cyst wall formed small, knoblike protrusions, which we re up to 180 nm long and 120 nm wide. Mature schizonts were present in the liver and other organs of gerbils between 11 and 14 days PI. Afte r inoculation of vipers of 3 different genera with mature sarcocysts f rom gerbils, oocysts developed in the intestine of Arabian saw-scaled vipers. A comparison of these data with those from previously describe d Sarcocystis species with snake-rodent life cycles suggests that Sarc ocystis gerbilliechis is a new species.