West Nile Virus Update: Number of Suspected Cases Falling

For the second straight week, the number of San Diego County residents testing positive for West Nile virus seemed to be leveling off.

While the total number of “confirmed” and “probable” human cases increased from 31 to 35, the number of suspected cases dropped from 10 to seven. 

Still, County public health and environmental health officials urged people to continue to protect themselves from mosquitoes that can transmit the disease and eliminate any standing water from recent rains that could give mosquitoes places to breed.

Earlier this week California public health officials announced that 32 Californians have died from West Nile virus in 2015, the highest single-year number since the disease arrived in 2003.

In addition, County vector control officials reported that the number of dead infected birds they are collecting is still increasing, an indication that the virus is still active in the environment.

As of Nov. 12, San Diego County officials reported:

  • 33 confirmed human cases, including five previously reported deaths, and two probable human cases. (Note: the California Department of Public Health uses patient symptoms and blood and spinal fluid tests to classify West Nile virus cases as “confirmed,” “probable,” “suspected” or “not a case.” For public reporting, state public health and the County consider both “confirmed” and “probable” cases as West Nile infections.)
  • Seven suspected human cases with state tests pending
  • 337 dead infected birds recovered
  • 48 batches of infected mosquitoes collected
  • Nine sentinel chickens testing positive for West Nile virus

County officials reminded people to follow the County’s “Prevent, Protect, Report” guidelines.

Prevent Mosquito Breeding: Dump out or remove any item inside or outside of homes that can hold water, such as plant saucers, rain gutters, buckets, garbage cans, toys, old tires, and wheelbarrows. Mosquito fish, available for free by contacting the Environmental Health Vector Control Program, may be used to control mosquito breeding in backyard water sources such as unused swimming pools, ponds, fountains and horse troughs.

Protect Yourself from Mosquito Bites: Protect yourself from West Nile virus by staying inside when most mosquitoes are most active, at dusk and dawn. Wear long sleeves and pants or use repellent when outdoors. Use insect repellent that contains DEET, picaridin, oil of lemon eucalyptus, or IR3535. Make sure screens on windows and doors are in good condition and secured to keep insects out.

Report Dead Birds and Green Swimming Pools: Report dead crows, ravens, jays, hawks and owls, and green swimming pools to the Environmental Health Vector Control Program by calling (858) 694-2888 or emailing

For more information about West Nile virus, go to San Diego County’s “Fight the Bite” website.


Gig Conaughton is a communications specialist with the County of San Diego Communications Office. Contact