Hawk Tests Positive for West Nile Virus; Protect Against Mosquitoes

A dead red-tailed hawk found in Valley Center has tested positive for West Nile virus, the first detection of the potentially deadly mosquito-borne disease in 2017 in San Diego County.

San Diego County environmental health officials immediately reminded people they should protect themselves from mosquitoes and follow the County’s “Prevent, Protect, Report” guidelines year-round.

Mosquitoes are cold-blooded and generally do not bite in temperatures 50 degrees Fahrenheit and lower. However, temperatures around the county have been moving up from winter lows into mosquito-breeding levels in recent weeks. At the same time, rains like the ones we’ve had and expect to have this week can give mosquitoes more places to breed around homes and communities.

Meanwhile, the Zika virus has joined West Nile virus as mosquito-borne diseases to defend against in San Diego County.

West Nile virus has been found naturally in the county environment since it arrived in 2003. Birds and animals can become infected and carry it. Native Culex mosquitoes can then pass it to people if they feed on the blood of an infected animal and then a person’s.

The Zika virus is not naturally found in San Diego County, but it is a tropical disease that has so far been brought here only by people who become infected traveling outside the country. Invasive Aedes mosquitoes — found in San Diego County since 2014 and notable for biting during daylight hours — can pass Zika and other tropical diseases from an infected person to other people by feeding first on the infected person and then biting someone who is not infected.

Last year, County environmental health teams had to hand-spray 10 different neighborhoods around the County between mid-August and late November to protect the public’s health after finding invasive Aedes mosquitoes living near County residents who tested positive for Zika after traveling abroad.

Zika generated more headlines last year, but West Nile virus remains a threat.

In 2016, 22 county residents tested positive for West Nile virus and two died. County Vector Control teams also found 266 dead birds that tested positive for the virus, as well as 99 batches of mosquitoes, nine sentinel chickens and one horse. Statewide, 436 Californians tested positive for West Nile virus in 2016 and 19 people died.

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 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 mosquito-borne illnesses by wearing 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 possible mosquito activity

Report increased mosquito activity, or neglected, green swimming pools and other mosquito-breeding sources, as well as dead birds — dead crows, ravens, jays, hawks and owls — to environmental health’s Vector Control Program by calling (858) 694-2888 or emailing vector@sdcounty.ca.gov. Also report if you are being bitten by mosquitoes during daylight hours, or if you find mosquitoes that match the description of Aedes mosquitoes by contacting the Vector Control Program at (858) 694-2888.

For more information about mosquito-borne illnesses, go to San Diego County’s “Fight the Bite” website. You can also get more information about how the County works to trap and test invasive Aedes mosquitoes, and hear how the public can help prevent mosquitoes from breeding in the following videos.

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