Dead Bird Surveillance for West Nile Virus (WNV) by the Public

Most people do not think about the animals mosquitoes commonly feed upon, but birds are the usual source of a blood meal for mosquitoes in our area! When you think about the situation, it makes a lot of sense. Birds are out where the mosquitoes frequent; bushes and trees, and birds nest in these areas making themselves a readily available meal. This also makes birds vulnerable to diseases mosquitoes may be carrying.

WNV was introduction into the United States in 1999, prior to that time our local feathered friends had a naïve immune system that had not encountered the WNV virus pathogen, and had no defense. Researchers noticed some species of birds found dying from the WNV pathogen, and it was an early indicator for WNV being in an area. The CDC states: “Since West Nile virus was discovered in the United States in 1999, the virus has been detected in over 300 species of dead birds. Although some infected birds, especially crows and jays, frequently die of infection, most birds survive.”

What is the importance of this unfortunate situation? Here is the scenario; a bird infected with West Nile Virus will enter an area, and the local mosquitoes will feed on this bird and acquire the virus. The virus then quickly replicates in the mosquito and is easily passed on to the victim of its next blood meal. Ultimately, you end up having more infected birds, that pass the virus to other mosquitoes, and then possibly to a human “dead end” host. The “dead end” human host means, that we usually do not end up infecting other feeding mosquitoes or animals.

Please help with this effort by reporting dead birds to the “West Nile Virus Dead Bird Surveillance System” that is coordinated by the California Department of Public Health (CADPH). You can report dead birds to our office (510-567-6800) or, to the Dead Bird hotline: http://www.westnile.ca.gov/report_wnv.phpg There is a toll-free phone number: 1-877-968-2473. This dead reporting by the public is a very valuable tool in mosquito surveillance. Last year we detected 2,442 WNV infected dead birds in California, and 96 of these were detected in Alameda County, though none in Albany.

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