The District’s West Nile virus surveillance program reports
several types of positive West Nile virus results, including dead
birds, mosquito samples (“pools”), sentinel chickens, and human
cases.
For more information about the District’s West Nile virus and
mosquito population surveillance, visit the Mosquito Surveillance page.
In the 2019 calendar year, the District closed out one of its
lowest seasons for West Nile virus activity since the virus first
appeared in San Mateo County in 2004. No virus was detected
in the county this year in any of the standard WNV surveillance
indicators.
As of December 1, 2019, there have been 231 dead birds reported
in San Mateo County. Of those, 57 have been suitable for testing
and all have tested negative for West Nile virus (WNV). No
mosquito pools or sentinel chickens have tested positive for West
Nile virus in San Mateo County in 2019.
As of November 1, 2019, there have been 215 dead birds reported
in San Mateo County. Of those, 53 have been suitable for testing
and all 53 have tested negative for West Nile virus (WNV). No
mosquito pools or sentinel chickens have tested positive for West
Nile virus in San Mateo County in 2019.
As of October 2, 2019, there have been 191 dead birds reported in
San Mateo County. Of those, 44 have been suitable for testing and
all 44 have tested negative for West Nile virus (WNV). No
mosquito pools or sentinel chickens have tested positive for West
Nile virus in San Mateo County in 2019.
As of September 3, 2019, there have been 179 dead birds reported
in San Mateo County. Of those, 38 have been suitable for testing
and all 38 have tested negative for West Nile virus (WNV). No
mosquito pools or sentinel chickens have tested positive for West
Nile virus in San Mateo County in 2019.
As of August 1, 2019, there have been 155 dead birds reported in
San Mateo County. Of those, 31 have been suitable for testing and
all 31 have tested negative for West Nile virus (WNV). No
mosquito pools or sentinel chickens have tested positive for West
Nile virus in San Mateo County in 2019.
As of June 28, 2019, there have been 120 dead birds reported in
San Mateo County. Of those, 23 have been suitable for testing and
all 23 have tested negative for West Nile virus (WNV). No
mosquito pools or sentinel chickens have tested positive for West
Nile virus in San Mateo County in 2019.
As of June 3, 2019, there have been 86 dead birds reported in San
Mateo County. Of those, sixteen have been suitable for testing
and all sixteen have tested negative for West Nile virus (WNV).
No mosquito pools or sentinel chickens have tested positive for
West Nile virus in San Mateo County in 2019.
As of September 28, 2018, there have been 330 dead birds reported
in San Mateo County. Of those, 103 have been suitable for testing
and five have tested positive (5%) for West Nile virus (WNV). Two
mosquito pools have tested positive for WNV, both from East Palo
Alto during the month of August. Positive birds and pools for
2018 are summarized in the tables below. No sentinel chickens
have tested positive for West Nile Virus in San Mateo County in
2018.
As of August 31, 2018, there have been 291 dead birds reported in
San Mateo County. Of those, 91 have been suitable for testing and
five have tested positive (5%) for West Nile virus (WNV).
Additionally, two mosquito pools have tested positive for WNV,
both from East Palo Alto. Positive birds and pools for 2018 are
summarized in the tables below. No sentinel chickens have tested
positive for West Nile Virus in San Mateo County in 2018,
although a sentinel chicken in Santa Clara County, near the
border with San Mateo County, tested positive in August.
The District laboratory has found no further sign of West Nile
virus in mosquitoes trapped in areas of East Palo Alto after this
week’s
adult mosquito control treatment.
As of August 1, 2018, there have been 247 dead birds reported in
San Mateo County. Of those, 66 have been suitable for testing and
two have tested positive (3%) for West Nile virus (WNV). No
mosquito pools or sentinel chickens have tested positive for West
Nile Virus in San Mateo County in 2018.
As of June 29, 2018, there have been 176 dead birds reported in
San Mateo County. Of those, 52 have been suitable for testing and
two have tested positive (4%) for West Nile virus (WNV). No
mosquito pools or sentinel chickens have tested positive for West
Nile Virus in San Mateo County in 2018.
As of May 25, 2018, there have been 115 dead birds reported in
San Mateo County. Of those, 25 have been suitable for testing and
two have tested positive (8%) for West Nile virus (WNV). No
mosquito pools or sentinel chickens have tested positive for West
Nile Virus in San Mateo County in 2018.
As of April 27, 2018, there have been 46 dead birds reported in
San Mateo County. Of those, 13 have been suitable for testing and
two have tested positive (15%) for West Nile virus (WNV). San
Mateo and Santa Clara counties are the only counties with
positive WNV dead birds (4) thus far this year. No mosquito pools
or sentinel chickens have tested positive for West Nile Virus in
San Mateo County in 2018.
On April 2nd, a dead American crow collected in South San
Francisco tested positive for West Nile virus. This is the second
dead bird positive for West Nile virus found in San Mateo
County in 2018. The first was collected in February in Foster
City.
On April 2nd, a dead American crow collected in
South San Francisco tested positive for West Nile virus. This is
the second dead bird positive for West Nile virus found
in San Mateo County in 2018. The first was collected in
February in Foster City.
