A map that details mosquitoes, dead birds, chickens, and horses that have tested positive for West Nile virus. You can zoom in and out of the map and click on the place-markers to get a detailed description of the date the positive activity was confirmed and the approximate location.

Click here to view archived West Nile virus activity in Contra Costa County.

For information regarding human cases, please click here.

Mosquito Samples: 10

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Dead Birds: 6

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Sentinel Chicken Flocks: 2

Note: Chickens do not die from West Nile virus. They develop antibodies to the virus which is detected in their blood.

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Horses: 0

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