PHOENIX – With triple-digit heat and nearly nonexistent rainfall, Phoenix seems an unlikely spot for this year’s West Nile virus epicenter. Yet, federal health officials say Arizona is the only state where the mosquito-borne virus is an epidemic.
“Minnesota may be the land of a thousand lakes, but we’re the land of thousands of abandoned swimming pools,” says Will Humble, head of disease control for the Arizona Department of Health Services.
Those swimming pools, plus irrigation canals that slice through parts of the city, patio misters and lush lawns designed to remind transplants of gardens they left behind have inadvertently turned neighborhoods into oases for mosquitoes.
“It didn’t use to be this bad. You never saw a mosquito,” said resident Gary Clark, 62, who takes his morning walk in an area where a high number of cases have been reported. “It’s even trouble sitting out in your backyard now.”
So far this year, at least 290 of the nation’s more than 500 West Nile cases are in Arizona; three of the 14 deaths were in Arizona. Nearly all the cases have been in the state’s most populous county, Maricopa, which includes the Phoenix metro area.
State health officials estimate at least 30,000 Arizonans may have the virus without knowing it. Some people never have symptoms at all. Only about 1 percent of West Nile victims develop the potentially dangerous inflammation of the brain or spinal cord – meningitis or encephalitis.
While Arizona doesn’t have a lot of mosquitoes because of long stretches of 100-plus degree days, one type of mosquito thrives here: the Culex tarsalis. The species is one of the best carriers of West Nile virus.
The water that people surround themselves with to combat the heat can be another major factor. From the air, pools form a checkerboard pattern across the desert landscape.
Of the approximate 600,000 residential swimming pools in the state, state health officials estimate about 10,000 are capable of breeding mosquitoes.
“What we’ve done is create miniature swamps in our back yard,” said David Ludwig, who oversees county health inspectors treating so-called green pools with larvicides.
Backyard pools are to Arizonans what ice scrapers are to Alaskans. Pools are everywhere and considered a necessity by some. But sometimes they are neglected – by cash-strapped owners who may have a broken pump or owners who have moved before the house has sold. The pools can turn to stagnant pond green in no time.
Also, many of the city’s older neighborhoods still use irrigation flooding for lawns, sometimes leaving standing water for days. They also have tall, mature trees. Besides mosquitoes, birds love these spots, and they can carry West Nile, too.
So far, the primary weapon has been to spray pesticide at night with fogging trucks that roam the neighborhoods. Maricopa County officials recently voted to spend more money to increase the spraying.
Associated Press
A truck sprays for mosquitoes earlier this month in Glendale, Ariz., where the West Nile virus has become an epidemic.
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