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09.08.16: San Gabriel Valley Mosquito and Vector Control District - West Nile Virus Update

San Gabriel Valley, CA – September 08, 2016

The San Gabriel Valley Mosquito and Vector Control District (SGVMVCD) has detected West Nile virus (WNV) throughout the San Gabriel Valley.  The District’s surveillance program monitors WNV in several systems to detect WNV in the community as soon as possible. The program monitors infections with WNV in mosquitoes, “sentinel chickens,” and dead birds reported to the California Department of Public Health’s WNV hotline. The following is an update as of September 06, 2016.

Positive Mosquito Samples 

(40) WNV-positive mosquito samples have been collected from the following cities. 

  • Altadena
  • Arcadia
  • Azusa
  • Covina
  • El Monte
  • Glendora
  • Pomona
  • San Dimas
  • San Gabriel
  • Walnut
  • West Covina 

Positive Dead Birds 

(10) WNV-positive dead birds have been reported from the following cities.

  • Altadena
  • Claremont
  • Glendora
  • Monrovia
  • Monterey Park
  • Sierra Madre
  • Temple City

Positive Sentinel Chickens

(13) sentinel chickens have been tested and found WNV-positive in the following cities.

  • Arcadia
  • Glendora
  • Monterey Park
  • Pomona

Positive Human Cases  

(9) WNV-positive human cases have been reported within the SGVMVCD’s jurisdiction.

(41) WNV-positive human cases have been reported in Los Angeles County.


Since its introduction in 2003, WNV has infected more than 5,588 people and caused 229 deaths statewide, according to the California Department of Public Health. West Nile virus is now endemic in California and presents a public health risk every year.

It is critical that residents remove all standing water on their property to prevent mosquito production. Mosquitoes lay their eggs in stagnant water such as neglected pools, buckets, miscellaneous containers, puddles, and ponds. Eggs can hatch and develop into biting adults in four to seven days.

The best precaution against WNV is to prevent mosquito bites. Mosquitoes that transmit WNV are most active between dusk and dawn. Residents should be extra cautious if outdoors during this time. Throughout the summer and fall, the following protective measures should be followed:

  • Wear mosquito repellent and protective clothing when outdoors while mosquitoes are active (especially around dawn and dusk).
  • Regularly inspect property to identify and remove sources of standing water where mosquitoes lay their eggs and grow.
  • Ensure doors and windows are properly screened and screens are in good repair.
  • Report increased mosquito activity, sources of standing water, and green pools to the District at (626) 814-9466 or online at
  • Report dead birds to the WNV Hotline at (877) WNV-BIRD ((877) 968-2473) or online at