By admin 
PHOENIX (AZFamily) — Arizona has more reported human West Nile virus cases than any other state, according to the latest data from the CDC, which shows 76 reported cases statewide.
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Maricopa County is driving much of the state’s total, with 58 confirmed human cases and five deaths so far this year.
Early and widespread activity
Maricopa County Vector Control Division Manager John Townsend said the county started seeing mosquitoes positive for West Nile virus earlier than usual.
“We started off early. We were getting positive mosquitoes for West Nile in February this year,” Townsend said.
“It’s almost year-round,” he added.
Mosquitoes themselves are also testing positive for the virus.
“So far, we’ve had 183 positive West Nile virus mosquito samples,” Townsend said.
Surveillance and response
The county has more than 850 traps that are set every week, according to Townsend.
Mosquitoes collected in traps are brought to a lab, where they are sorted, tested and tracked for West Nile virus. That surveillance helps crews determine where the virus is present and where to focus their response.
The locations with the most activity have shifted this year, Townsend said.
“They used to start off in the Southeast Valley, Gilbert Mesa, Queen Creek in that area. This year we had a lot in Peoria, Glendale, in those types of areas,” Townsend said.
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When a trap tests positive, crews treat that area overnight, when mosquitoes are most active. Crews also use larvicide in standing water.
“And hopefully that will keep the mosquitoes from becoming adults,” Townsend said.
Monsoon rain a factor
Following rain from recent monsoons, crews said it will be a week before they know whether the moisture created new breeding grounds for mosquitoes that carry West Nile virus.
“I hope that we peaked early, but we’ll see. You know, last year we had a kind of a surge in September into October, so we’ll just have to see how it goes,” Townsend said.
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