Not that we want to start a local-news-style panic, but everyone should be aware that West Nile Virus is back again and has now been found in dead animals in four Bay Area counties this year, the last one being Alameda County, where two dead crows tested positive in the past week.
The dead birds were found separately, one in the Oakland hills and one in Pleasanton, and this follows on a total of 13 reported cases of dead animals who tested positive for the virus in Contra Costa, San Mateo, and Santa Clara Counties. The only reported human case of the virus, which was fatal, was a Sacramento man who died last month and who may have had other underlying health conditions.
As most of you likely know, the virus is carried by mosquitos and is dangerous in that affects the elderly and those with compromised immune systems. It first made its appearance in California around 2003. (Those who lived on the East Coast in the late 90s will recall the initial panic at the arrival of the virus, and the subsequent mass insecticide spraying that went on in cities along the eastern seaboard.) In California, there have been a total of 150 fatalities in the last ten years, and a total of 4,104 reported cases of human infection. It comes on with flu-like symptoms, and anyone who's had a bug bite and gets such symptoms should tell their doctor.
The only thing you can do by way of precaution is to use insect repellant if you're spending time outdoors (especially in the East Bay), and to remove any standing water from your yard where mosquitoes can breed.