California reports record West Nile cases and first L.A. County death this year
California's West Nile virus infections have risen to a five-year high, with 30 human cases and three deaths statewide, including the first fatality in Los Angeles County.
California has experienced a surge in mosquito activity after an unusually warm winter and a March heat wave, pushing West Nile virus infections to the highest level in five years. The state health department reported 30 confirmed human cases and three fatalities, while Los Angeles County recorded its first death this year, a resident of the San Fernando Valley who developed a neurological complication.
The L.A. County Health Officer, Muntu Davis, said the department has documented 15 infections in the county, about half of them in the San Fernando Valley, and urged residents to use DEET-based repellents, eliminate standing water, and keep screens fitted to reduce exposure.
Mosquitoes that feed on infected birds transmit the virus, and the typical season runs from June to November. This year, the season began roughly two months early, according to Susanne Kluh of the Greater Los Angeles County Vector Control District, who linked the early activity to the record-warm winter.
Statewide surveillance shows that 24% of dead birds tested positive for West Nile, compared with a five-year average of 13%, and about 8 per 1,000 mosquitoes are positive, up from the average of 5 per 1,000. Most infected individuals remain asymptomatic; roughly 20% develop fever and moderate symptoms, while about one in 150 experience severe illness such as meningitis or encephalitis, especially older adults and those with underlying health conditions.
There is no specific treatment or vaccine for West Nile virus. State Health Officer Dr. Erica Pan warned that August and September are peak transmission months and advised heightened precautions, particularly for high-risk groups.