Submitted to: International Journal for Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 28, 2000
Publication Date: N/A
Interpretive Summary: Sarcocystis neurona is a single-celled parasite. It is the most common cause of a fatal disease in horses called equine protozoal myeloencephalitis (EPM). The opossum is the reservoir host for S. neurona and horses are thought to become infected with S. neurona by ingesting the resistant stage (sporocyst) excreted in feces of the infected opossum. How wopossum become infected with S. neurona is unknown. Scientists at the Beltsville Agricultural Research Center and the Virginia Tech have isolated for the first time Sarcocystis neurona from the brain of a sea otter with neurologic signs. The characteristics of the isolate reported will be of interest to pathologists, biologists and parasitologists.
Sarcocystis neurona was isolated from the brain of a juvenile, male southern sea otter (Enhydra lutris nereis) suffering from central nervous system disease. Schizonts and merozoites in tissue sections of the otter's brain reacted with anti-Sarcocystis neurona antiserum in an immunohistochemical test. Development in cell culture was by endopolyogeny and mature schizonts were first observed at 3 days postinoculation (PI). PCR of merozoite DNA using primer pairs JNB33/JNB54 and restriction enzyme digestion of the 1,100 bp product with Dra indicated the organism was S. neurona. Four of 4 interferon-y gene knockout mice inoculated with merozoites developed S. neurona-associated encephalitis. Antibodies to S. neurona but not S. falcatula, Toxoplasma gondii, or Neospora caninum were present in the serum of inoculated mice. This is the first isolation of S. neurona from the brain of a nonequine host.