San Diego County has confirmed 11 human West Nile virus cases as of Sept. 16, the highest count since 2016. Lagoons near Del Mar and Solana Beach are among 54 waterways receiving county larvicide treatments through October.
The affected individuals range in age from 22 to 89, with four hospitalizations, according to the County of San Diego.
"Typically we have 1-3 cases a year, and it's just September, and we have 11," Dr. Mark Beatty, a County Health official, told CBS 8.
Three of the 11 cases involved Coronado residents, according to county officials. County Vector Control crews began truck-mounted pesticide treatments across roughly 6,000 Coronado properties on Friday, Sept. 25, with a second round scheduled for Saturday, Sept. 26. Both sessions run from 1 to 6 a.m. Additional treatments may follow the next week depending on conditions.
No confirmed cases have been reported in Del Mar, Solana Beach or Rancho Santa Fe. But San Elijo Lagoon and San Dieguito Lagoon, both bordering those communities, are among 54 local waterways receiving routine aerial larvicide drops from the county's Vector Control Program, according to the City of Solana Beach. The next scheduled aerial treatments are Oct. 7, Oct. 8 and Oct. 29.
County officials warned that the fall rainy season, potentially intensified by El Niño, could increase mosquito breeding, according to CBS 8. In October 2024, an elderly San Diego County resident with a compromised immune system died of West Nile virus encephalitis, according to the Coronado Times.
There is no treatment for West Nile virus.
The virus spreads through infected mosquito bites and can cause fever, headache, body aches, vomiting and rash. Severe illness or death is rare but possible.
The county's Vector Control crews use AquaDuet for truck-mounted spraying. The U.S. Environmental Protection Agency (EPA) has approved the pesticide, which county officials said does not pose a risk to people or pets as applied. The mist dissipates in under 30 minutes. Beekeepers and residents who keep insects or fish outdoors should cover their habitats during early-morning treatments.
County officials urged residents to dump standing water from buckets, plant saucers, garbage cans, toys, tires and wheelbarrows. Wearing long sleeves and pants and using repellent containing DEET, picaridin or oil of lemon eucalyptus also reduces risk. Free mosquitofish are available from the Vector Control Program for use in stagnant pools, rain barrels, ponds and fountains.
Residents can report increased mosquito activity, neglected swimming pools or dead birds to the county's Vector Control Program at 858-694-2888 or [email protected].
