Description of Sarcocystis campestris sp.n. (Protozoa: Sarcocystidae): a parasite of the badger Taxidea taxus with experimental transmission to the Richardson's ground squirrel, Spermophilus richardsonii.

Sporulated oocysts (10.1 X 15.3 mu m) and free sporocysts (8.0 X 10.2 mu m, with a large, round sporocyst residuum consisting of a single refractile granule) of Sarcocystis campestris n.sp. were obtained from intestinal scrapings of Taxidea taxus (carcasses frozen 2 years at -20 deg C) from Saskatchewan, Canada. When free sporocysts were given orally to juvenile Spermophilus richardsonii, acute fatal sarcocystosis developed in some of the squirrels after 11 to 13 days. 2nd-generation meronts were present 9 to 12 days after infection in the vascular endothelium of many tissues (especially the lungs). Cysts developed in skeletal muscle, contained metrocytes (7 X 5 mu m) on day 30 and, beginning on day 46, bradyzoites (12.0 X 3.5 mu m) were present. Cysts were macroscopic as early as day 258. Squirrel carcasses containing cysts (76 days after infection) were fed to Sarcocystis-free T. taxus. The prepatent period was 9 days and patency lasted at least 13 days. Both animals were ill early in the patent period and passed unformed faeces during patency..