"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 back yard 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.
Last year was the first time the virus appeared in areas west of the Continental Divide. It hit Colorado hard and drifted slowly into Arizona's northeastern tip, then down south. It's now spreading in California, where at least 116 cases have been reported and at least five people have died.
Several factors have contributed to Arizona's outbreak.
"It's like the planets, everything has to align" for an outbreak to occur, said John Roehrig, chief of the CDC's arboviral diseases branch in Fort Collins, Colo.
While more humid climates have more mosquitoes, they are also more prepared to deal with "nuisance mosquitoes," while Arizona isn't.
And 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.
It does well in suburban settings and likes to feed on humans.
The species can breed in small pools of standing water, such as in wheelbarrows, kiddie pools and plant saucers. Since the species is so dominant here, it doesn't have to compete with other types of mosquitoes for breeding spots.
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.
But they also opted against the aerial spraying recommended by the CDC.
"I think it was the right choice," Humble said. "If you spend $3 to $6 million on aerial spraying, your whole budget is gone in a matter of days. What are you going to do for the rest of season?"
The CDC's Roehrig said his agency still believes aerial spraying is superior. However, that recommendation was made before county officials decided to beef up spraying efforts, he said.
Federal officials are watching to see if the county is able to slow the virus' spread.