LA Reports Local West Nile Virus and Dengue Cases

The Los Angeles County Department of Public Health (LACDPH) has identified human West Nile virus (WNV) cases in Los Angeles County for the 2025 season.

Four people were hospitalized with WNV illness beginning in late July 2025 through late August and are recovering.

LACDPH has identified WNV cases in the Antelope Valley, San Fernando Valley, and central Los Angeles areas.

Public Health reports human cases of WNV every year in LA County, averaging 56 cases per year over the last five years.

This announcement does not include cases in Long Beach and Pasadena.

WNV spreads through the bite of an infected mosquito. About three-quarters of reported cases have had severe disease, and approximately 10% of patients with severe WNV die from complications.

Although not all mosquitoes carry this virus, the type of mosquito that spreads this virus is found throughout Los Angeles County.

"Detecting West Nile virus in our district is a reminder that this virus has been present in California — and right here in our community — for over 20 years. It's part of our local environment and continues to reappear year after year. With the recent rains and more in the forecast, conditions are ideal for mosquitoes to breed," said Brenna Bates-Grubb, Community Outreach Specialist, Antelope Valley Mosquito and Vector Control District, in a press release on September 17, 2025.

"We urge everyone to take simple steps to protect themselves and their families: use EPA-approved mosquito repellent, keep swimming pools clean and maintained, drain any standing water around your home, and check for sources like buckets, plant saucers, or clogged gutters that can fill with rainwater. It only takes a small amount of water for mosquitoes to breed."

There is no specific treatment for West Nile virus disease, and no vaccine is available to prevent infection. Currently, WNV vaccine candidates are being evaluated for their effectiveness.

Additionally, LA County states that Dengue is a disease caused by a virus that is transmitted to people mainly through the bites of infected mosquitoes. LA has reported 36 locally transmitted Dengue cases in 2025, which is more than the 14 cases confirmed last year.

Similar to WNV, no Dengue vaccine is available in LA in 2025.

Although millions of travelers visit this area of California, as of September 19, 2025, the U.S. CDC has not issued a Travel Health Advisory specifically focused on LA County.