West Nile may bite Utah hard

Utah health, agriculture, wildlife and mosquito-control experts are painfully aware that West Nile virus cases tend to explode the year after it first appears in a state.

In Utah, that means the upcoming mosquito season could be brutal if residents don't take precautions.

"We have reason to be concerned there will be a fair number of cases this year," said Dr. Scott Williams, state Department of Health executive director. He said although there are ways to slow down the spread and protect against it, officials do not believe they can prevent it entirely.

West Nile is carried by mosquitoes and spread to birds. Infected mosquitoes can pass the virus to humans and horses, as well. People can also, on rare occasion, receive the virus from a blood transfusion or transplant, mother to baby in the womb or through a needle stick.

Monday, officials from various agencies gathered at the health department to brief reporters on what to expect when the mosquitoes that can carry West Nile virus become active, expected to start about mid-May. Human cases are likely to appear around July 1 and peak in August, but sometimes human cases occur before the virus is otherwise found in the horse and bird population that usually precedes human infection.

There are key points for Utahns to keep in mind. First, the chance of getting West Nile virus is very small. Of those who are bitten by an infected mosquito, 80 percent will show no symptoms. Nearly 20 percent will have symptoms of West Nile fever, including headache, fever, muscle aches, nausea and vomiting, eye pain, etc., but will usually make a complete recovery in three to six days.

More problematic are the small number of people who will show the neurological symptoms: meningitis, encephalitis or acute flaccid paralysis from spinal cord damage. That's about one in 150 people who are infected. Ten percent of those with neurological symptoms will die, or about one in 1,000 infected people, said Dr. Robert Rolfs, state epidemiologist.

Those most at risk are 50 and older. Treatment of the virus is merely supportive. There is no human vaccine, though at least one is being developed and could be available in a few years.

Despite the fact that most people will not become ill from infection, Rolfs said he has become "a little less comfortable saying it's a mild, flu-like illness."