Despite a lighter mosquito season in San Mateo County than in previous years, health officials are cautioning residents to be aware of West Nile virus after the first infected animal case was reported in a squirrel found July 9.
The squirrel — an Eastern grey squirrel found in San Mateo — signaled that West Nile season has arrived this year in the county.
The virus has been in the county since 2004, according to the San Mateo County Health Department.
West Nile virus is a blood-borne disease transferred by mosquitoes to both small animals — including birds and squirrels — and large ones, such as horses and humans. There have not been any reported human cases yet.
West Nile virus can cause serious illness, including paralysis, high fevers and comas in approximately one in 150 infected people, according to the Center for Disease Control.
One in five experience flu-like symptoms including nausea, body aches and skin rashes, while 80 percent of the general population will experience no effects at all.
In Foster City, the dry season during spring resulted in a heightened mosquito problem. Diminished rainfall prevented the stagnant water in the city’s below-sea-level drainage system from completely flushing out.
Other than in Foster City and the Redwood Shores area, San Mateo County residents pay a tax of $1.86 for every $100,000 of their home’s value to fund mosquito-abatement services. To report dead animals or to request help with mosquito problems, call the San Mateo County Abatement District at (650) 344-8592.