July 29, 2004
Disease control experts are bracing for a south East Valley outbreak of West Nile virus, despite the area’s mysterious lack of human cases so far this year.
State and county health officials say they don’t understand why the same West Nile virus that plagued the south East Valley in 2003 has all but spared the area so far this year.
Still, the number of mosquitoes testing positive for the disease at Queen Creek and Gilbert sites has increased dramatically in the past two weeks, causing some disease experts to reserve their optimism.
"We were fully expecting the south East Valley to come on strong," Arizona Department of Health Services program manager Craig Levy said. "It didn’t, but it may be now."
Arizona leads the nation in confirmed human cases of West Nile virus this year with 163, most of which have been among Valley residents.
Of those, only six have been in Chandler, two in Gilbert and one in Queen Creek.
Strangely, the virus has been most prevalent in central and northern Phoenix, the last place health experts expected to see it.
"Last year, Chandler was the area that really lit up the brightest," Levy said.
There were only 13 confirmed human cases statewide in 2003, the year the virus first reached Arizona, so comparisons with the West Nile virus’ current activity are meaningless, Levy said.
But, the virus infected many south East Valley birds and horses last fall, which makes this year’s relative calm a mystery.
The bad news is that state health officials have seen a recent spike in the number of infected south East Valley mosquitoes, Levy said, with four of six test sites in Queen Creek and Gilbert testing positive in mid-July compared with only one site in June.
He urged residents to continue keeping property devoid of standing pools ideal for mosquito breeding and using insect repellent with DEET.
"I do not want anybody to let their guard down thinking it’s not going to happen this year," he said.
Because the disease is already much more prevalent this year, there’s a good chance it could spread heavily into the East Valley before the mosquito season ends in October, Levy said.
For now, Maricopa County vector control supervisor Kirk Dymbrowski said his colleagues are relieved about the lack of human infections in some potentially active areas.
"To have a spot on the map which is blank is beautiful," he said. Health officials are already working 12- to 14-hour days to keep up with the existing cases.
Levy and Dymbrowski agreed that the situation is likely to get worse in Arizona before it gets better. Based on environmental factors, Levy predicted the disease will peak in 2005, followed by a gradual decrease in cases.
Meanwhile, Dymbrowski said, residents can greatly reduce their chances of infection by taking the necessary precautions.
"It’s very preventable, just like a sexually transmitted disease," he said.