Equine West Nile cases spike in Missouri

COLUMBIA, MO. — The number of equine West Nile virus (WNV) cases surpassed the number recorded for the entire season last year, according to Gayle Johnson, DVM, University of Missouri-Columbia (MU).

Most new WNV cases in horses have occurred in the southern half of the state, but birds and mosquitoes carrying the disease have been distributed over the entire state with crows and blue jays having the highest occurrence.

More than 50 percent of the horses tested in the last month have the disease, according to a MU report, and scientists are reporting a high percentage of birds are testing positive as well. An estimated 15 percent of the state's equine population is predicted to be most susceptible this season, Johnson says.

"With the peak of the virus occurring in September, we will likely see more increases to come," Johnson says. "We strongly encourage horse owners to consider immunizing or boosting their animals to prevent this potentially devastating disease."

In 2002, the state had 600 documented cases of West Nile virus, Johnson adds. An effective vaccine significantly reduced the number of diagnosed cases, with only 16 reported in 2004 and 22 reported in 2005.