SARCOCYSTIS MEPHITISI N. SP. (PROTOZOA: SARCOCYSTIDAE), SARCOCYSTIS NEURONA-LIKE AND TOXOPLASMA-LIKE INFECTIONS IN STRIPED SKUNKS

Two structurally distinct types (A, B) of microscopic sarcocysts were found in muscles of 4 of 5 feral skunks. Type A sarcocysts had sarcocyst walls of up to 6 mm thick. The villar protrusions (Vp) on the sarcocyst wall were up to 5 mm long. The Vp were constricted at the base, expanded in the middle, and had a blunt tip. Numerous microtubules were present in the Vp and in the granular layer. Bradyzoites were up to 11 mm long and up to 3.2 mm wide. Based on the distinctiveness of the Vp, a new name, Sarcocystis mephitisi is proposed for type A sarcocysts. Type B sarcocysts had a relatively thin (;1-2 mm thick) sarcocyst wall and the Vp were slender and tapered toward the tip. These sarcocysts were structurally similar to S. neurona sarcocysts. A Toxoplasma gondii-like tissue cyst was found in a section of tongue of 1 of the 4 skunks. Species of Sarcocystis have a 2-host prey-predator life cycle, with herbivores as intermediate hosts and carnivores as defini- tive hosts (Dubey et al., 1989). The intermediate host becomes infected with Sarcocystis by ingesting sporocysts, oocysts, or both excreted in the feces of the definitive host. After a brief period of schizogony, the parasite encysts in muscles and forms sarcocysts. The definitive host becomes infected by ingesting sarcocysts in infected muscles of intermediate hosts. Some an- imals act both as intermediate and definitive hosts, but usually not for the same species of Sarcocystis (Dubey et al., 1989). The striped skunk (Mephitis mephitis) can act as a definitive host for Sarcocystis rileyi of ducks (Wicht, 1981), but little is known of sarcocysts in the skunk. Erdman (1978) found sar- cocysts in muscles of 3 skunks from Iowa. These sarcocysts were 300 mm long. Dogs fed these sarcocysts shed sporocysts.