Overview: West Nile
West Nile is a vector-borne disease that primarily circulates among certain bird populations, according to Mahmood Nikbakhtzadeh, adjunct assistant professor of Public Health at San Diego State University. Mosquitoes can feed on these infected birds and then transmit the virus to humans.
As part of ongoing efforts to reduce the risk of disease, San Diego County conducted pesticide spraying in neighborhoods across San Diego and La Mesa.
Mosquitoes trapped during a routine monitoring in Rolando last month tested positive for West Nile virus.
These are the first mosquitoes to test positive for the virus within the county since 2023, according to county communications officer Donna Durckel.
So far this year, four dead birds have tested positive, but no human infections have been reported, according to a press release from the county.
Durckel said that health officials regularly set mosquito traps across different parts of the county year-round to monitor population levels and test for potential diseases.
After catching mosquitoes carrying the virus at the end of June, they conducted a follow-up test, which confirmed more infected insects in the area.
As a result, the county is required to spray for adult mosquitoes to help prevent the virus from spreading.
“Even if it was just one mosquito that tested positive, we would still take action,” Durckel said.
The county’s Vector Control Program carried out pesticide-misting treatments through July 14.
Trucks sprayed AquaDuet, an EPA-approved pesticide deemed low-risk for people, pets and the environment.
According to the press release, officials aimed to reduce the adult mosquito population across approximately 4,000 parcels in Rolando, extending into La Mesa.
West Nile is a vector-borne disease that primarily circulates among certain bird populations, according to Mahmood Nikbakhtzadeh, adjunct assistant professor of Public Health at San Diego State University.
Mosquitoes can feed on these infected birds and then transmit the virus to humans.
According to Nikbakhtzadeh, most people do not experience any symptoms, but the few who do may suffer from temporary headaches, body aches, joint pain and other symptoms similar to the common cold.
He noted that about 5-7% of those with the virus may face the potentially fatal Meningoencephalitis disease, which leads to inflammation in parts of the brain and surrounding membranes.
County officials urge residents to take proactive steps to reduce mosquito risks by following the “Prevent, Protect, Report” guidelines.
This includes cleaning up standing water around homes to prevent mosquitos from breeding.
Residents are also encouraged to protect themselves from bites by using insect repellents and other protective measures.
Additionally, the public can report unmaintained water sources and other mosquito-breading grounds, as well as dead birds to the County Vector Control Program.
