Cache County officials say they know all about the mosquito-borne Cache Valley virus but see little health threat to humans or animals here.

A deer hunter had one leg amputated and was lying in a coma in North Carolina Thursday, four months after he was bitten by a mosquito carrying the Cache Valley virus.But a Logan official said there is no case on record in Utah of human or animal illness from the virus, which was discovered in Cache Valley 40 years ago.

"We know the virus is here and we know it is circulated through mosquitoes and there's always a potential but, at this point, we have not seen a problem," said Elmer Kingsford, environmental health supervisor for Logan city.

Although his department tests animals for viruses transmitted by mosquitoes, it has not tested for Cache Valley virus in the past eight to 10 years, Kingsford said. "We've not seen anything that indicates we need to."

Kingsford said officials may conduct spot checks because of the North Carolina case but said the public should not be alarmed.

Checks with the Bear River Health Department and the state epidemiologist turned up no documented case of illness from Cache Valley virus and experts say the North Carolina case is extremely rare.

The 27-year-old victim, whose name has not been released, was hunting at the Pee Dee National Wildlife Refuge near Wadesboro, N.C., when he was bitten by mosquitoes.

A week later he complained of flulike symptoms and was eventually taken to Duke University Medical Center, where it took doctors two months before they diagnosed Cache Valley virus. Meantime, the hunter fell into a coma and doctors had to amputate his right leg.

Officials in North Carolina said it is the first known case of illness from Cache Valley virus in the Southeast.

So rare is illness from Cache Valley virus that if 1,000 people were bitten by mosquitoes carrying it, it would be unlikely that even one would get seriously ill, said Charles Calisher, a biology professor at Colorado State University and nationally recognized expert on Cache Valley virus.

The virus can cause encephalitis, a brain disease, in humans and birth defects and spontaneous abortions in sheep and cattle.

The virus was named by a team of U.S. public health experts who discovered it in mosquitoes after setting up a field station in Cache Valley from 1956-1958, Kingsford said.

He said the virus, which can be found from Canada to Mexico, is endemic to Cache Valley. "It has been around probably since Day 1," Kingsford said.