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West Nile Virus Season Begins

Surveillance for West Nile virus begins in California in mid-April each year. The District protects residents from this mosquito-borne disease with control methods that target mosquitoes in the larval stage, as well as mosquito population monitoring, disease surveillance and public education. The District laboratory conducts West Nile virus surveillance with sentinel chickens, dead bird testing, and mosquito testing.

In late April, we set up our seasonal sentinel chicken surveillance coops. Chickens are very important for detecting mosquito-borne infectious diseases like West Nile virus, Saint Louis encephalitis virus, and Western equine encephalitis virus because they are easy to work with and don’t get sick from the virus like many other birds. Our hens will be living in special coops we’ve established in San Mateo and East Palo Alto until the end of the summer and then will be released for adoption to good homes.

The District collects and conducts testing on dead wild birds that are reported by residents. Dead birds should be in good condition without signs of decay or trauma. All bird species are accepted, except water fowl, poultry and pigeons. Residents are encouraged to call the state hotline phone number 1-877-WNV-BIRD (1-877- 968-2473), which opens with live operators in mid-April. Online reports can be made at

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