Topline:
Los Angeles County public health officials have identified four human cases of West Nile virus infections. These are the first human cases reported for 2025 and people are being urged to take precautions against mosquitoes, according to the department.
Why now? We’re still in the middle of the West Nile virus season. The cases come weeks after the first infected mosquitoes with the virus were detected. "The first human cases of West Nile virus are an important reminder that we all need to take steps to prevent mosquito bites and mosquito breeding,” said L.A. County Health Officer Muntu Davis. “Mosquitos thrive in hot weather, increasing the risk of bites and mosquito-borne diseases.”
What do we know? Hospitalizations for the reported cases began in late July through late August, according to L.A. County Public Health. Those patients are recovering.
Background: L.A. County has reported an average of 56 cases annually over the last five years. Keep in mind, the total number of people infected with the virus in the county is likely much higher because most people do not experience zero to mild symptoms, according to the county. Symptoms can include fever, muscle aches, tiredness and sometimes a rash.
What can you do? You can help prevent spread of West Nile by removing the main place where mosquitoes breed — standing water. Staying indoors at dusk and dawn can also help since this is when Culex mosquitoes are most active.
Go deeper… to see where infected mosquitos are being found in California.