Activity Patterns of St. Louis Encephalitis Virus (Flaviviridae) in Mosquito Communities in a Subtropical Region of Argentina.

Our aim with this study is to analyze the temporal and spatial dynamics of St. Louis encephalitis (SLEV) in mosquitoes collected from urban and rural environments in the central region of Chaco Province in the subtropical region of Argentina. Mosquitoes were captured between 2012 and 2015. A total of 81 mosquito pools were analyzed (2,105 mosquitoes) for SLEV detection, and 41 of these pools tested positive for SLEV (n = 1,675 individuals; 50%). Thirteen mosquito species were found to be infected with SLEV during this study, nine of which were reported infected for the first time in Argentina. The virus activity was recorded throughout the study period, both in urban and rural environments. The mosquito species in both environments that were infected with SLEV included Culex maxi, Culex brethesi/eduardoi, Culex bidens, and Aedes scapularis. Similar species composition and marked fluctuation in monthly activity were observed for species of the genus Culex between environments. Likewise, a similar seasonal pattern of infected species with a higher frequency of positive SLEV results was recorded during Autumn (19/41) in both environments. Our study confirms the active circulation of SLEV throughout the analyzed period in several mosquito species and its generalist nature in terms of the vectors it can infect in a subtropical region.