WNV Surveillance
September 7, 2017

San Mateo County

As of August 25, 2017, there have been 286 dead birds reported in San Mateo County. Of those, 52 have been suitable for testing and 1 has tested positive (2%) for West Nile Virus (WNV). No dead squirrels or mosquito pools have been tested for West Nile Virus in San Mateo County thus far this year.

The district asks residents to call in to report dead birds or tree squirrels.  Specimens that appear to have been dead for less than 24 hours and are in good condition will be tested for WNV.  Residents should contact the state WNV hotline at 877-WNV-BIRD (968-2473).  Reports can also be made online at


WNV has been detected in 33 counties in 2017 (see map), compared to a five year average of 37 counties at this date. 59 human case of West Nile Virus has been reported in California this year, from twelve counties. Statewide, 5,562 birds have been reported and 1,411 have been tested with 251 positive results (18%).  2,284 mosquito pools have tested positive for West Nile Virus, compared to a five-year average of 2,070 positive mosquito pools at this time. 130 positive sentinel chickens has been reported from ten counties.