Los Angeles County health officials confirmed the region's first West Nile virus death of the year on Thursday, coinciding with a statewide warning that activity from the mosquito-borne disease has reached its highest level in five years across California.
The deceased was a San Fernando Valley resident hospitalized with neurological illness from a severe West Nile virus infection, according to the Los Angeles County Department of Public Health. Further details about the individual were not released. So far this year, Los Angeles County has documented 15 West Nile virus infections, a count that excludes cases from Long Beach and Pasadena, which manage their own health departments. Half of these county-level infections have been reported in the San Fernando Valley, and officials noted the number of cases is above the five-year average for this point in the season.
Dr. Muntu Davis, the Los Angeles County Health Officer, extended condolences to the family, calling the loss a "serious threat posed by mosquito-borne diseases." Davis advised residents to use insect repellent, eliminate any standing water where mosquitoes can breed, and ensure windows and doors have screens without tears.
This local announcement arrived as the California Department of Public Health reported that West Nile virus activity statewide is at a five-year peak. As of August 14, California had seen 30 human cases, including three deaths, across 13 counties this year, a number also above the state's five-year average for this time. Dr. Erica Pan, Director and State Health Officer for the CDPH, emphasized that August and September are the peak transmission periods, urging everyone to take precautions, especially since the virus can be fatal for the elderly and immunocompromised.
Signs of West Nile virus have been detected in 32 California counties through ongoing surveillance of mosquitoes, dead birds, sentinel chickens, and even horses. State officials report that over 24% of tested dead birds have been positive for the virus, up from a five-year average of 13%. Similarly, eight out of every 1,000 mosquitoes tested were positive, compared to an average of five per 1,000. Locally, Greater Los Angeles County Vector Control District General Manager Susanne Kluh noted that the virus activity began almost two months early this year, attributed to the warmest winter on record, leading to widespread countywide detections despite fewer mosquitoes. Kluh reiterated the importance of wearing repellent, especially at dawn and dusk.
West Nile virus spreads to people through the bite of an infected mosquito. Most individuals infected won't experience symptoms, but about one in five will develop a fever and other issues. Roughly one in 150 people face severe symptoms, which can include high fever, stiff neck, muscle weakness, and in serious cases, meningitis, encephalitis, or paralysis. Those over 50 and individuals with certain health conditions are at higher risk for severe illness. There is currently no vaccine or specific treatment for the virus.
