First Case Of West Nile Virus In 2026 Identified In LA County

LOS ANGELES, CA — Health officials have identified the first human case of West Nile virus in Los Angeles County this year, the county Department of Public Health announced this week.

The patient, who lives in the Antelope Valley, first developed symptoms in late June. West Nile virus is a mosquito-borne illness that can be contracted from the bite of an infected mosquito, according to the DPH.

"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," Brenna Bates-Grubb of the Antelope Valley Mosquito and Vector Control District said. "It's part of our local environment and continues to reappear year after year."

Public health officials report human cases of West Nile virus every year in Los Angeles County, averaging 41 annually over the last five years, excluding cases reported separately by the Pasadena and Long Beach health departments.

Officials noted the actual number is likely much higher because most people experience either no illness or mild symptoms. Three quarters of reported cases are severe and 10% of those die from complications, according to officials.

There are no vaccines or treatment for West Nile in people. Most people who become infected with the virus do not become sick. But about 20 percent develop a fever and other symptoms. And one in 150 develop a serious illness that can become fatal, according to the U.S. Centers for Disease Control and Prevention.

Those at greatest risk include seniors and people with compromised immune systems.

West Nile virus is typically detected in the county in the summer. The season's warm overnight temperatures contribute to mosquito populations and disease activity, according to health officials.

Officials said residents should take precautions to reduce conditions in which mosquitos proliferate and protect themselves from getting bitten:

• Dump out stagnant water around the home weekly, as mosquitos can lay their eggs in as little as a quarter-inch of standing water
• Remove unused containers that can hold standing water
• Use insect repellent that contains CDC-recommended ingredients: picaridin, DEET, oil of lemon eucalyptus (or PMD), or IR3535

City News Service contributed to this report.