|Topper, M - WALTER REED MED. CENTER|
Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 25, 2002
Publication Date: N/A
Interpretive Summary: Sarcocystis neurona is a single-celled parasite of horses. It causes a fatal illness (EPM) in horses in Americans. Its life cycle is not fully known. Opossums are its definitive (reservoir) host. Horses become infected by ingesting the resistant stage of the parasite shed in opossum feces. Scientists at the Beltsville Agricultural Research Center have found S. neurona sarcocysts (muscle cysts) in muscles of naturally infecte skunks which could be a source of infection for the opossum. The also describe a new species of Sarcocystis, S. mephitisi in muscles of skunks. These results will be of interest to biologists, horse owners and parasitologists.
Technical Abstract: Two structurally distinct types (A, B) of microscopic sarcocysts were found in muscles of 4 of 5 feral skunks. Type A sarcocysts had up to 6 m thick sarcocyst wall. The villar protrusions (Vp) on the sarcocyst wall were up to 5 m long. The Vp were constricted at the base, expanded in the middle, and had a blunt tip. Numerous microtubes were present in the Vp and in the egranular layer. Bradyzoites were up to 11 m long and up to 3.2 m 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 m thick) sarcocyst wall and the Vp were slender, and tapered towards the tip, these sarcocysts were structurally similar to S. neurona sarcocysts. A Toxoplasma gondii-like tissue cyst was found in section of tongue of 1 of the 4 skunks.