Los Angeles County confirms first West Nile virus death, study suggests drought may increase risk
The Los Angeles County Department of Public Health on Friday confirmed the first recorded West Nile virus death in Los Angeles County this year.
The man, whose details have been kept anonymous, was hospitalized in the San Fernando Valley with a neurological disorder caused by a mosquito-borne virus. In Southern California, October is the middle of mosquito season.
In 2025, 14 cases of West Nile virus infection have been recorded throughout Los Angeles County; half are in the San Fernando Valley.
Data from the Los Angeles County Department of Public Health shows that since 2020, Los Angeles has experienced an average of 58 cases of West Nile infection per year and an average of one death per year.
According to the Centers for Disease Control and Prevention, West Nile virus affects about 2,000 Americans each year. The CDC says viral infections can cause a variety of symptoms, including mild symptoms of illness including fever, headache, body aches, vomiting, rash, or diarrhea.
More serious and worrisome conditions may result in stiff neck, coma, disorientation, tremors, convulsions, muscle weakness, vision loss, numbness, or paralysis. Officials warned that the effects of severe illness could be permanent or lead to death.
In some cases, the infection causes no symptoms.
The California Department of Public Health notes that many species of mosquitoes in the genus Culex are the primary carriers of the virus and are found throughout Los Angeles County.
The San Fernando Valley region recently experienced water outages and has been experiencing below-average rainfall and drought conditions over the past 12 months.
A 2025 study from the National Institutes of Health showed that drought increases risk factors for West Nile virus. Data from more than 50,000 traps show that while drought conditions reduce overall mosquito populations and standing water bodies, it concentrates infected mosquitoes and birds (which also carry the disease) around limited water sources. The result is that it spreads faster among smaller populations and continues to infect humans. In the San Fernando Valley, where dry conditions are expected to persist throughout the La Niña season, reduced water supplies could lead to increased infection rates.
To avoid contracting West Nile virus, the CDC recommends limiting outdoor activities during the day when mosquitoes are most active. Officials also say exposure can also be reduced by emptying or replacing containers of stagnant water, where mosquitoes can easily breed, installing window screens, wearing protective skin coverings when outdoors or using insect repellent.
