EEE Outbreak in Wisconsin

EEE Outbreak in Wisconsin

Aug 15, 2001
By staff

Eau Claire, Wis.- Following news that 18 horses in northwestern Wisconsin recently died from a suspected Eastern equine encephalomyelitis (EEE) outbreak, Dr. Robert Ehlenfeldt, Wisconsin's assistant state veterinarian, blames insufficient vaccination.

That may be at least one reason why the state hasn't seen an outbreak to this degree in 20 years, according to Ehlenfeldt.

"(Typically) here in the state office, we get a report of a singleton case (of EEE) every couple of years," he says. "You don't hear about encephalitis around here. People get complacent and they forget to vaccinate."

Two of the cases were confirmed as EEE on Aug. 7 by the USDA National Veterinary Services Laboratories and the Minnesota Department of Agriculture. The tests for West Nile virus (WNV) in both horses were negative.

According to Ehlenfeldt, all of the clinically affected horses had not been vaccinated for EEE, and they were pasture-kept in an area that is considered lowlands or swamp. These conditions, combined with increased rainfall and high temperatures, have created a bumper crop of mosquitoes that spread the disease.

Officials report that the cases didn't look like WNV, Venezuelan equine encephalomyelitis, or Western equine encephalomyelitis.

Horse owners and veterinarians have been advised to vaccinate/booster horses for EEE in the face of this outbreak. Enhanced passive surveillance for additional horse cases is under way, and diagnostic tests submitted from six additional horses with symptoms are pending.