Experimental Infection of North American Birds with the New York 1999 Strain of West Nile Virus

TLDR

The study evaluated WNV transmission dynamics by exposing 25 North American bird species to infectious mosquito bites. Viremia titers, clinical outcomes, cloacal and oral shedding, seroconversion, tissue persistence, and susceptibility to oral and contact transmission were monitored. Results showed that passeriform and charadriiform birds were the most reservoir‑competent, with five passerine species (Blue Jay, Common Grackle, House Finch, American Crow, House Sparrow) exhibiting the highest viremia; eight species died; 17 of 24 species shed virus cloacally and 12 of 14 orally; contact transmission occurred in four species and oral transmission in five; persistent infections were found in tissues of 16 survivors, offering insights for surveillance and control.

Abstract

Abstract To evaluate transmission dynamics, we exposed 25 bird species to West Nile virus (WNV) by infectious mosquito bite. We monitored viremia titers, clinical outcome, WNV shedding (cloacal and oral), seroconversion, virus persistence in organs, and susceptibility to oral and contact transmission. Passeriform and charadriiform birds were more reservoir competent (a derivation of viremia data) than other species tested. The five most competent species were passerines: Blue Jay (Cyanocitta cristata), Common Grackle (Quiscalus quiscula), House Finch (Carpodacus mexicanus), American Crow (Corvus brachyrhynchos), and House Sparrow (Passer domesticus). Death occurred in eight species. Cloacal shedding of WNV was observed in 17 of 24 species, and oral shedding in 12 of 14 species. We observed contact transmission among four species and oral in five species. Persistent WNV infections were found in tissues of 16 surviving birds. Our observations shed light on transmission ecology of WNV and will benefit surveillance and control programs.