Prevalence of Sarcocystis neurona sporocysts in opossums (Didelphis virginiana) from rural Mississippi

Sarcocystis species sporocysts were found in intestinal scrapings from 24 o f 72 opossums (Didelphis virginiana) from rural Mississippi. The number of sporocysts in each opossum varied from a few (<100 000) to 187 million. Spo rocysts from 24 opossums were bioassayed for Sarcocystis neurona infections by feeding to gamma-interferon knockout (KO) mice. S. neurona was detected in the brains of KO mice fed sporocysts from 19 opossums by immunohistoche mical staining with anti-g. neurona specific polyclonal rabbit serum, and b y in vitro culture from the brains of KO mice fed sporocysts. The isolates of S, neurona from opossums were designated SN16-OP to SN34-OP. Merozoites from 17 of 19 isolates tested at the 25/396 locus were identical to previou sly described S. neurona isolates from horses. The high prevalence of S. ne urona sparocysts in D. virginiana suggests that this opossum constitutes an ample reservoir of infection in the southern United States. Published by E lsevier Science B.V.