Detection of West Nile in N. Utah nets warnings

West Nile virus is back. The Salt Lake Valley Health Department has found an infected mosquito pool in Salt Lake County.

"That means it's probably all over this area," said spokeswoman Pamela Davenport.

It marks the first detection in the state since official annual surveillance began a couple of weeks ago. And it has public health officials again warning residents throughout the state to take precautions to avoid being bitten in the hours between dusk and dawn, when the mosquitoes that carry the virus are active. C. tarsalis populations have already been detected in at least Salt Lake and Utah counties.

Precautions against what the Centers for Disease Control and Prevention call an "established seasonal epidemic in North America" include using mosquito repellent with DEET, Picaridin or oil of lemon eucalyptus and wearing long sleeves and pants during those hours. People should also get rid of standing water near their homes. They also suggest making any screen repairs to keep the flying critters out of your house.

It's impossible to predict from year to year how many West Nile infections Utah will see or how virulent a season it will be. 2006 was one of the worst, with 158 reported human infections, a third of them the more severe, neurologic form.

That doesn't mean only 158 people were infected or that one in three bites to humans resulted in severe illness. Most people who are infected don't develop much in the way of symptoms, and cases don't get reported unless people become ill enough to seek medical care. Even then, unless a blood sample is checked for the virus, it's not part of the official count.

"People get pretty sick from it before we hear about them," Davenport said.

Most of those infected were older than 40, but cases were reported in infants through young adults as well, according to Rich Lakin, communicable disease manager with the Utah Department of Health.

In all last year, statewide surveillance efforts found 466 infected mosquito pools, 107 chickens from the sentinel flocks, 75 wild birds and 59 horses. Human cases were reported between July and October.

Of those, 105 were a milder form of West Nile fever, 53 had neurological symptoms and five of the latter group died.

Symptoms range from nearly nonexistent to very serious, including high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. The symptoms can last weeks, according to the CDC. Neurologic effects may never go away.

Information and a weekly tally that is updated Wednesday afternoons are online at www.health.utah.gov/wnv.

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E-mail: lois@desnews.com