Climate Change Increases West Nile Virus Risk in Southern California, El Niño Forecast Raises Concerns
Southern California experienced its most severe mosquito season in a decade, with Los Angeles County accounting for over half of the reported human West Nile virus cases statewide. A study by UC Berkeley researchers, analyzing Los Angeles-area data from 2006 to 2016, identified a critical temperature threshold for West Nile virus transmission. When average temperatures remained below approximately 70 degrees Fahrenheit, the likelihood of mosquitoes carrying the virus was significantly lower. However, once temperatures surpassed roughly 73 degrees Fahrenheit, transmission rates sharply increased, correlating with a rise in human infections. Coastal Los Angeles, where summer temperatures typically range from the high 60s to low 70s, is particularly vulnerable, as even a slight temperature increase can push conditions into dangerous territory, as observed this year. The California Department of Public Health reported 528 serious human infections and 32 deaths due to West Nile virus as of November 6.
