Skunk named as adversary in EPM cases

Skunk named as adversary in EPM cases

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Aug 20, 2001
By dvm360.com staff

The striped skunk is being monitored closely by researchers who believe the animal serves as an intermediate host for Sarcocystis neurona, a parasite that causes equine protozoal myeloencephalitis (EPM) in horses.

The skunk's habitat spans the United States, Canada and north Mexico, which may help researchers understand the wide geographic distribution of EPM, according to The Horse Interactive.

A study involving the link between the skunk and EPM is being conducted by researchers at the University of Florida, Washington State University and the Universty of Missouri.

"We were looking at a variety of aspects of (S. neurona) and how it interacts with the horse, skunk and oppossums," says Dr. Ellis Greiner of the University of Florida College of Veterinary Medicine.

In the study, skunks that were at first negative for the parasite were inoculated with a parasite collected from an infected oppossum. Skunks developed antibodies to S. neurona, sarcocysts built up in their muscles and the muscles were fed to oppossums that shed sporocysts in their waste matter. A foal and lab mice were inoculated with the sporocysts, and the foal developed antibodies to the parasite in its central nervous system fluid. The mice all developed antibodies and died or had to be euthanized.

The cat has also been identified as an intermediate host in the laboratory.

"The difference between the skunk and the cat study is that in order to get a really good infection in the cat, researchers had to immunosuppress the cat before the parasite it could be observed in the cat muscles," says Andy Cheadle of the University of Florida. "We didn't do anything to the skunks and they became heavily infected with sarcocysts (when the sporocysts were administered). The skunk has been reported to be naturally infected with sarcocysts, therefore it is highly likely to be a natural intermediate host."

Research groups are also examining other potential hosts.