West Nile virus cases and deaths surge in Los Angeles and Orange counties
Los Angeles and Orange counties account for about two-thirds of California’s reported West Nile infections this year, with a sharp rise in cases and fatalities compared with last year.
Mosquito-borne West Nile virus infections have risen sharply in Southern California, with Los Angeles and Orange counties together representing at least 63% of the 378 human cases reported by the state health department this year. Orange County recorded 68 cases and six deaths as of Oct. 15, the highest fatality count in the county in more than a decade, while Los Angeles County logged 249 infections and 12 deaths, up from 22 cases and two deaths the previous year.
Health officials attribute the spike to a combination of warmer temperatures, recent rains and standing water that create breeding grounds for the female Southern House mosquito. "Rain creates more breeding areas, and the warmer it is, the more active (mosquitoes) are," said Brian Brannon, spokesman for the Orange County Mosquito and Vector Control District. He added that older neighborhoods with aging infrastructure tend to have more pooled water, concentrating infected mosquitoes.
Vector control teams are responding by applying mineral oil to water pools to suffocate mosquito larvae and by increasing public education on personal protection. "Wherever there is standing water, that’s where the mosquitoes will be, and we have to be smarter than them," Brannon said.
The disease remains largely asymptomatic, but severe cases can cause encephalitis and death, especially among people over 60 or with weakened immune systems. Families of victims described rapid declines after initial flu-like symptoms, highlighting the seriousness of the infection.
Officials also monitor dead birds, which serve as reservoirs for the virus. As of Oct. 20, Los Angeles County reported 162 dead birds, the most in the state, followed by Orange County with 119. The Greater Los Angeles County Vector Control District warned that mosquito infection rates and bird mortality have exceeded the five-year average.
Public health agencies urged residents to use insect repellent, wear long sleeves and pants, eliminate standing water, and report dead birds to the California Department of Public Health. "Like you put on your seatbelt, spray some bug spray when you go out for a walk," said Dr. Anissa Davis, medical director of communicable disease control at the Orange County Health Care Agency.