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Current West Nile Virus Information for San Mateo County

2024

In January, a dead American crow collected from Foster City tested positive for West Nile virus.  In February, a second dead American crow collected from Foster City tested positive for West Nile virus.  Both results indicated that the birds were likely not recently infected, and risk to the public at this time is low.  The cool weather and frequent rains during this time dramatically reduce the risk of mosquitoes breeding and transmitting West Nile virus to residents at the moment.  Our staff continue to check and treat water sources throughout the County to prevent mosquito breeding.

 

 

2023

October typically marks the end of the West Nile virus season. The California state West Nile virus hotline closed live operator service on October 13, 2023. However, residents can continue to report dead birds online at westnile.ca.gov. District staff will collect and test suitable birds through the winter months. For information about West Nile virus throughout the state, please visit: https://westnile.ca.gov/

In 2023, no mosquito pools tested positive for West Nile virus in San Mateo County. No sentinel chickens tested positive for West Nile virus.  For information about West Nile virus in humans and horses, visit: https://westnile.ca.gov/ or www.cdfa.ca.gov/AHFSS/Animal_Health/Wnv_Info.html

In 2023, a total of 15 dead birds tested positive for West Nile virus in San Mateo County. Positive birds were found in Belmont (1), Burlingame (1), Foster City (1), Redwood City (1 in Redwood City; 3 in Redwood Shores area; 2 on the border of Redwood City and North Fair Oaks), San Carlos (1), and Menlo Park (5). Additional mosquito trapping and testing done in areas where dead birds were found did not found any positive mosquitoes.

For tips on how to avoid mosquito bites and select a safe, effective mosquito repellent, click HERE.

 

 

Page last reviewed: February 7, 2024

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