Natural exposure for St. Louis Encephalitis and West Nile viruses in birds of prey from La Pampa, Argentina

Viruses transmitted by arthropods represent the most important emerging virus in the world. The Saint Louis encephalitis (SLEV) and West Nile virus (WNV) are transmitting by Culex mosquitoes as vectors and several bird species as hosts. The purpose of this research was to study the exposure of birds of prey communities for SLEV and WNV in La Pampa province. We analyzed 524 plasmas samples by plaque reduction neutralization test. Samples belonged to 8 species of birds of prey and were collected from 2008 to 2015. The 20, 83% (n=24) of the Black Vultures (Coragyps atratus), 33, 33% (n=3) of the Southern Crested Caracara (Caracara plancus) and 0, 28% (n=360) of the American Kestrels (Falco sparverius) were positives for SLEV; while the 81, 48% (n=27) of the Swainson´s Hawk (Buteo swainsoni) were positives for WNV. One Swainson´s Hawk was positive for both viruses (3.7%). No positive sample was found in plasmas from the 4 remaining species (Milvago chimango, Athene cunicularia, Glaucidium brasilianum and Cathartes aura). Our results confirm the circulation of SLEV and WNV in resident and migratory populations of birds of prey in agroecosystems of La Pampa. Although the overall seroprevalence detected for this group is low compared to other groups of birds, the prevalences for some of the species analyzed were very high. These findings point to a need for further studies on the circulation and ecological characterization of these viruses in the bird communities of the La Pampa agricultural systems.