Thursday, September 12, 2002 - As the nation's most intense West Nile outbreak rages, now stretching from one mosquito-gnawed coast to the other, a small skirmish has broken out among plagued communities.

Call it a mini mosquito war.

For reasons crystal clear only to the callers themselves, folks ringing Centers for Disease Control and Prevention investigators in Fort Collins are rooting for specific mosquitoes to take the blame for the outbreak. So says a CDC skeeter expert fielding the sometimes anguished, sometimes angry calls from mosquito control districts and state health departments.

Callers from the Northeast "hoped" a salt-marsh-dwelling mosquito going by the handle of Aedes sollicitans was spreading West Nile there.

Down South - where the bulk of the nation's 1,086 infections and 45 deaths have occurred - folks want to pin the rap on the Asian Tiger mosquito.

That suspect skeeter, formally known as Aedes albopictus, is nicknamed for its black-and-white racing stripes and feeds on humans day or night. It hitched a ride from Japan into the United States in water pooled in tires and has attracted attention because it may not need to feed on infected birds to refill its viral tanks.

"I've had so many hysterical calls: 'Aedes albopictus has to be transmitting virus in my little town, otherwise we wouldn't have four dead people,"' recounted Harry Savage, a CDC research entomologist.

The callers take a "Why did this happen to us" mentality and jump to the conclusion the new mosquito in town is to blame, Savage said.

Actually, West Nile is simply an opportunistic virus that strikes wherever environmental conditions are ripe.

It has hooked up with more than 30 kinds of mosquitoes. But West Nile's favorite accomplices to spread disease are in the Culex clan - C. pipiens, C. quinquefasciatus and C. tarsalis - plain Janes that strike at dusk and dawn.

Truth be told, even staid researchers are taken by the sleek, slightly sexy A. albopictus mosquitoes.

"It's an unusual circumstance where you have an African virus in an Asian mosquito in North America," Savage said. "You have both a vector and a virus that aren't native ... Neither of those things should be here."

That skeeter, some surmise, is searching for blood in all the wrong places because global warming has so raised temperatures that it can call new and different places home.

Such as East St. Louis, Ill.

An adherent of the global warming theory, Illinois State University ecology professor Steven Juliano has another intriguing theory about how the Asian Tiger mosquito is influencing West Nile's spread in the United States. So intriguing that Juliano changed his mind about publicizing it, for fear another researcher might work on it first.

The CDC will say it's intrigued by the theory that the Asian Tiger mosquito can directly pass West Nile virus from mother to offspring. Other mosquitoes get tainted by gnawing on infected birds.

While investigating Louisiana's outbreak, researchers gathered A. albopictus eggs. They hatched the eggs, which look like grains of black pepper. Those mosquito offspring were frozen, and are ready to be mashed and sampled to see if the West Nile virus is in the skeeter slurry.

It's a long shot. One in 1,400 mosquito eggs can inherit West Nile from its mother, according to theory and past outbreaks with other viruses. The question, however, is more than idle curiosity. Since it first arrived in Houston in the late 1980s, the Asian tiger mosquito has whined and dined its way throughout the swampy Southeast, becoming the dominant nuisance mosquito there.

CDC experts don't expect it to be a major player in West Nile transmission. And they hope the hunt for Asian Tigers won't overshadow other, more valuable mosquito control efforts.

Skeeters are particular about where they breed. Some prefer saltwater. Some like stinky, stagnant pools. For others, only fresh ponds that appear one day and evaporate suddenly will do.

The sobering risk is that panicked public officials might squander resources, spending scarce dollars to annihilate the wrong mosquito. The CDC has handed out $54 million since West Nile first appeared in the U.S. in 1999 to underwrite mosquito control, among other preventive measures.

Denver Post science writer Diedtra Henderson can be reached at 303-820-1910.