The first West Nile virus death has been confirmed in LA County, as studies show drought may increase the risk

The first recorded death from West Nile virus in LA County this year was confirmed Friday by the Los Angeles County Department of Public Health.

The person, whose details have been withheld, was hospitalized in the San Fernando Valley for a neurological illness caused by a mosquito-borne virus. In Southern California, October is the middle of fly season.

In Los Angeles County, 14 documented West Nile virus infections in 2025; Half are in the San Fernando Valley.

LA has averaged 58 West Nile infections per year since 2020, with an average of one death per year, according to data from the Los Angeles County Department of Public Health.

West Nile virus affects about 2,000 Americans a year, according to the U.S. Centers for Disease Control and Prevention. According to the CDC, a viral infection can have a number of symptoms, including mild illness symptoms such as fever, headache, body aches, vomiting, rash or diarrhea.

A more serious and related case can cause neck stiffness, fatigue, disorientation, tremors, pain, muscle weakness, vision loss, numbness, or paralysis. Officials warn that the effects of severe disease can be permanent or result in death.

In some cases, the infection does not cause symptoms.

The California Department of Public Health notes that there are several species in the Culex mosquito genus, which is the primary vector of the virus, found in Los Angeles County.

The San Fernando Valley region has recently experienced water scarcity and has experienced consistently below-average rainfall and drought over the past 12 months.

In a 2025 study from the National Institutes of Health, research showed that drought increased risk factors for West Nile virus. Data from more than 50,000 traps revealed that while the drought has reduced overall bee populations and standing water bodies, it has strengthened the presence of infected bees and birds, which also carry the disease, around limited water sources. The result is a rapid transmission rate among small populations, which infects humans. In the San Fernando Valley, where drought conditions are expected to continue through the dry La Niña season, reduced water resources may increase 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 that emptying or relocating containers of standing water (where mosquitoes breed), installing window screens, and wearing skin-protective clothing or using insect repellent can also reduce exposure.