West Nile virus confirmed in horse

The reach of the West Nile virus in North Florida grows wider.

State health officials confirmed Friday the first case of West Nile virus in a Florida horse. The virus had been discovered earlier this month in five crows in North Florida and South Georgia - marking the first time the mosquito-borne disease had appeared south of North Carolina.

The first infected crow in Florida was found in Jefferson County on July 6. The horse confirmed Friday also was from Jefferson County.

No human cases of West Nile virus have been discovered in Florida so far.

The disease first appeared in the United States in 1999 when it struck birds, horses and people in the New York City area.

"We are being faced with a challenge of controlling the mosquitoes that carry this new virus," said Florida Agriculture Commissioner Charles Bronson. "We will be just as vigilant in our efforts for all of Florida as we are responding to this outbreak in North Florida."

The horse afflicted with West Nile Virus was one of five in Jefferson County believed stricken by eastern equine encephalitis in early July. Preliminary tests in Florida on three of the horses indicated the possible presence of West Nile virus, and blood samples were sent to the National Veterinary Lab in Ames, Iowa, for specific testing for the virus.

The results came back positive Friday on one horse but have not been completed on the other two. The horse confirmed with West Nile has since died; the other two horses remain alive.

"They are still pretty high on the suspect list," said William Jeter, a Department of Agriculture veterinary manager.

Jeter said preliminary tests also found West Nile virus in a horse in Nassau County, near Jacksonville, and he expects the virus may be found in other counties. Since June, about 50 horses in nearly a dozen rural North Florida counties have been diagnosed with eastern equine encephalitis.

Indications are that West Nile virus is less fatal to horses than eastern equine encephalitis: 33 of 88 horses (38 percent) in the Northeast afflicted with West Nile virus died. The mortality rate in Florida for horses afflicted with eastern equine is more than 90 percent.

The pattern in the Northeast is that human cases of West Nile virus developed about three or four weeks after horses got the disease.

"But that's in (urban areas) where the horses and people live right next to each other," Jeter said. "We can't say the pattern will be the same in rural counties."

Officials emphasize that people have only a remote chance of being bitten by an infected mosquito and that only a tiny fraction of those bitten by an infected mosquito becomes ill.

"We don't want people to think this is the end of the world," said Terry McElroy, a spokesman for the state Department of Agriculture and Consumer Services. "We are always concerned about eastern equine and St. Louis encephalitis, and West Nile is simply a variation on those."