SANTA CLARA (KCBS) — This year is shaping up to be one of the worst for West Nile virus since 2005, both here in the Bay Area and across the state. Public health officials are attempting to figure out why but climate change and drought are likely factors.

More than one-third of the California’s birds that have tested positive for West Nile Virus come from Santa Clara County where mosquitoes fogging operations have hit an all-time time as have the number of human cases.

Russ Parman, the acting manager for the Santa Clara County Vector Control District, said that the state’s record drought is playing a major factor.

“What happens is, you have scarcer water sources. Both the mosquito and the birds used those water sources so they’re actually physically, geographically close to each other and when this happened, that just simply enhances the ability of mosquitoes to go back and forth and keep the cycle going with all these infected birds,” he said.

West Nile virus was originally discovered in Africa and was first detected in the eastern United States in 1999. Since then, the mosquito-borne disease has spread throughout the most of the country, including California.

According to the California Department of Public Health, 562 people have infected statewide with West Nile Virus this year—including 17 deaths.

Over the summer, the SCVCD found as many as 1 in 20 mosquitoes infected with West Nile in the area.

The good news, Parman said, is that the mosquito season is almost over.

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