Abstract: Over the last 17 years, the numbers of annual WNV-positive pools generated by mosquito trapping in Iberia Parish, Louisiana have fluctuated greatly. Since 2010, they have generally remained low, less than 5 positive pools/yr. 2012 was a big outbreak year, when the parish generated 166 WNV-positive pools. 51 of those pools came from the city of New Iberia, with another 20 from the heavily industrialized northwestern part of the parish. 96% of the pools consisted of Culex quinquefasciatus. In 2013 and 2014, another 20 WNV-positive pools were obtained, all but 5 of them either from the city or from the northwestern corner of the parish. Beginning in 2018, the pattern changed. That year, 25 positive pools were obtained, only 2 of which came from the city and 2 from the northwestern sector. Most came from rural areas in the eastern part of the parish. In 2022, as of this writing, 13 positive pools have been obtained. All but 1 have been from rural areas, 8 from the eastern part of the parish. 4 pools have consisted of species other than Cx. quinquefasciatus, including Cx. erraticus, Cx. salinarius, and Anopheles quadrimaculatus. Changes in the distribution of West Nile in our mosquito population are possibly due to changes in its distribution in the bird population, with more birds from east of the parish bringing the virus into the area.
