Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2009
Publication Date: 10/20/2003
Citation: Stanek, J.F., Stich, R.W., Dubey, J.P., Reed, S.M., Njoku, C.J., Lindsay, D.S., Schmall, L.M., Johnson, G.K., LaFave, B.M., Saville, W.J.A. 2003. Epidemiology of Sacocystis neurona infections in domestic cats (Felis domesticus) and its association with equine protozoal myeloencephalitis (EPM) case farms and feral cats from a mobile spay and neuter clinic. Veterinary Parasitology. 117:239-249. 2003.
Interpretive Summary: Sarcocystis neurona is a single celled parasite that causes a fatal neurologic disease of horses and other animals. Cats are one of its reservoir hosts. Scientists at the Beltsville Agricultural Research Center and the Ohio State University found that 14 of 35 (40%) of cats on horse farms had antibodies to S. neurona, indicating a common infection in this reservoir host. These findings will be of interest to biologists, parasitologists, veterinarians, and horse owners.
Technical Abstract: Equine protozoal myeloencephalitis (EPM) is a serious neurologic disease in the horse most commonly caused by Sarcocystis neurona. The domestic cat (Felis domesticus) is an intermediate host for S. neurona. In the present study, nine farms, known to have prior clinically diagnosed cases of EPM and a resident cat population, were identified and sampled accordingly. In addition to the farm cats sampled, samples were also collected from a mobile spay and neuter clinic. Overall, serum samples were collected in 2001 from 310 cats, with samples including barn, feral and inside/outside cats. Of these 310 samples, 35 were from nine horse farms. Horse serum samples were also collected and traps were set for opossums at each of the farms. The S. neurona direct agglutination test (SAT) was used for both the horse and cat serum samples (1:25 dilution). Fourteen of 35 (40%) cats sampled from horse farms had circulating S. neurona agglutinating antibodies. Twenty-seven of the 275 (10%) cats from the spay/neuter clinic also had detectable S. neurona antibodies. Overall, 115 of 123 (93%) horses tested positive for anti-S. neurona antibodies, with each farm having greater than a 75% exposure rate among sampled horses. Twenty-one opossums were trapped on seven of the nine farms. Eleven opossums had Sarcocystis sp. sporocysts, six of them were identified as S. neurona sporocysts based on bioassays in gamma interferon gene knockout mice with each opossum representing a different farm. Demonstration of S. neurona agglutinating antibodies in domestic and feral cats corroborates previous research demonstrating feral cats to be naturally infected, and also suggests that cats can be frequently infected with S. neurona and serve as one of several natural intermediate hosts for S. neurona.