Contra Costa County

Positive Case of West Nile Virus Found in Contra Costa County Mosquitoes

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Contra Costa County health officials are warning people to be careful after its first positive case of West Nile in a group of mosquitoes. 

Workers with the county’s Mosquito and Vector Control District checked catch basins near the Marsh Fire site looking for any type of mosquito activity Monday.

“We don’t want adult female mosquitoes capable of laying eggs and leading to more mosquitoes flying from here and over to the marsh,” said Nola Woods with the Contra Costa Mosquito and Vector Control District 

She’s referring to the site of the Marsh Fire where more the 200 million gallons of water was pumped onto the site to finally put it out after it burned for a few weeks. 

But the big body of water could potentially serve as the ideal breeding environment for mosquitoes. A cause for concern with the county confirming its first pool of mosquitoes in Oakley carrying West Nile. 

“When the water is moving, the mosquitoes aren’t able to reach the surface of the water so if they’re a developing mosquito they can’t survive,” said Woods.

The Marsh Fire also burned through a good amount of vegetation which the district says can serve as a hideout for mosquitoes. 

Between the moving water and lack of vegetation, the conditions aren’t favorable for mosquitoes, at least for now. 

It’s why the district will continue to survey the area as long as there is water on the site. 

“It does make the area at this time less attractive to mosquitoes but we will continue to survey the area if the situation changes,” said Woods.

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