Abstract

We report early seasonal activity of West Nile virus (WNV) infection in cliff swallow nestlings from the Fort Collins, Colorado area. Using TaqMan reverse transcription-PCR, we were able to detect WN virus in oral swab samples taken from nestling cliff swallows. The timing of virus activity in the nestling population predates the general human activity of WN in the Fort Collins area by 5 wk. West Nile virus activity in nestlings corresponded spatially to case reports of viral infection in humans. This surveillance method may prove useful in designing a sensitive, spatially explicit, early-detection monitoring system that can predict risk to human populations and thus help guide mosquito control efforts.