First Human, Travel-Related West Nile Virus Case of 2020 Reported in County

Video by Suzanne Bartole

A 61-year-old man from Alpine has been confirmed to be the first person in San Diego County in 2020 to test positive for West Nile virus, the County Health and Human Services announced today.

The man was hospitalized, tested and the California Department of Public Health confirmed the case Aug. 11. He has recovered.

The man said he had traveled to Yuma, Arizona where it is believed he contracted the virus.

Since Jan. 1, 2020, there have been two West Nile virus positive detections in mosquitoes during routine trapping by the County Vector Control Program, one in the Del Mar Area and the other in the Black Mountain Ranch area.

There were only three human cases of West Nile virus in San Diego County in 2019 and two in 2018.

West Nile virus is mainly a bird disease but can be transmitted to people by certain species of native San Diego County mosquitoes that first feed on an infected bird or animal and then a bite a person.

Eighty percent of people who become infected with West Nile virus never know it and never suffer any symptoms. About one in five people who are infected develop a fever and other symptoms such as headache, nausea, fatigue, skin rash or swollen glands. About 1 out of 150 infected people could get extremely ill and die.

County public health and environmental health officials say the best way for people to protect themselves against the virus is to follow the County’s Prevent, Protect, Report guidelines. These guidelines can also help county residents protect themselves from mosquitoes that transit West Nile virus as well as invasive Aedes mosquitoes that can transmit tropical diseases, including Zika, dengue and chikungunya, if they first bite an infected person and then bite non-infected people.

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 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.

José A. Álvarez is a communications specialist with the County of San Diego Communications Office. Contact