Exposure of raptors in central Argentina to St. Louis encephalitis and West Nile viruses

Abstract

Arthropod-borne viruses are the most important emerging viruses worldwide. Saint Louis encephalitis (SLEV) and West Nile (WNV) viruses are vectored by Culex mosquitoes and amplified by several bird species. We carried out an extensive retrospective serosurvey study to analyze the exposure of free ranging birds of prey to SLEV and WNV in central Argentina. A total of 523 plasma samples were analyzed by Plaque Reduction Neutralization Test (PRNT) for both viruses. Samples belonging to eight raptor species were collected from 2008 to 2015. Of the individuals tested for WNV, 81.5% of the Swainson´s Hawks (Buteo swainsoni) were positive. In the other hand, 20.8% of the Black Vultures (Coragyps atratus), 25% of the Southern Caracaras (Caracara plancus) and only 0.3% of the American Kestrels (Falco sparverius) had detectable neutralizing antibodies against SLEV. Only one Swainson´s Hawk was positive for both viruses (3.7%). No neutralizing antibodies were found in samples from Turkey Vulture (Cathartes aura), Chimango Caracara (Milvago chimango), Burrowing Owl (Athene cunicularia) and Ferruginous Pygmy-Owl (Glaucidium brasilianum). Our results confirm SLEV and WNV circulation in resident and migratory populations of raptors in central Argentina, despite the fact that seroprevalence was variable among species. These findings suggest the need of further studies regarding circulation and ecological characterization of these viruses in bird communities in Argentina.