Why West Nile cases aren’t rising in Maricopa County despite wet winter

PHOENIX (3TV/CBS 5) - We usually don’t start worrying about mosquitoes until well into monsoon season, but this year, things are different after our rainy winter. “There has been a little increase in mosquito activities but mostly in areas with irrigation or accumulation of water,” said Johnny Diloné, a spokesman for the Maricopa County Environmental Services. The county’s Vector Control Division deploys around 800 routine traps each week. “In thousands of areas that we’ve identified throughout the years as problem areas of mosquito breeding and we monitor them monthly,” he said.

That determines which areas need to be treated, which are both areas with high populations of the insects and locations with high numbers of mosquitoes carrying viruses. “We count them. We separate them by specie. The females are the ones that can carry viruses,” Diloné said.

So far this year, the Arizona Department of Health Services has only reported one case of West Nile, while Maricopa County says it hasn’t had any cases this year. 2021 was the largest year for West Nile cases in both mosquitoes and humans with almost 1,500 human cases in Maricopa County. “As we kept on getting more and more rain than whatever eggs were out there, mosquito eggs, they were washed away and washed out so that’s why we didn’t see so much of an increase in mosquito activity as folks were expecting,” Diloné said.

If there’s an area in your neighborhood with a lot of mosquitoes, Maricopa County has an area on its website to file that complaint.

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