West Nile Virus in Hummingbirds in California, USA, 2005-17.

Although West Nile virus (WNV) infects many avian species, the prevalence and impact of WNV in hummingbirds (Family Trochilidae) have not been described. We focused on hummingbird mortality and WNV infection using data from the state of California's Dead Bird Surveillance Program for the years 2005-17. The overall prevalence of WNV in tested carcasses was 10.1% (49/486), with annual prevalence ranging from 0-28%. Prevalence by county ranged from 0-40% while prevalence by species ranged from 0-12%. We demonstrated that hummingbirds were naturally infected with WNV and displayed temporal and spatial patterns of infection consistent with trends observed in other avian species.