Examining the Effects of Precipitation and Temperature on Mosquito Population Density and West Nile Virus Positive Samples in Allegheny County from 2016-2022

Abstract Vector-borne diseases continue to rise as a serious public health threat throughout the world. West Nile Virus (WNV) is a mosquito-borne virus that is endemic throughout the United States. While most cases of WNV are asymptomatic, certain individuals face severe neurological symptoms and in rare cases, fatality. Outside of humans, several avian and horse populations are affected by the virus as well. Many states’ including Pennsylvania created vector control programs to monitor WNV and several other vector-borne diseases. Allegheny County Health Department’s (ACHD) Housing and Community Environment Office (HCE) are responsible for conducting the program in Allegheny County. Surveillance of WNV is conducted by the setting of gravid traps specifically designed to trap Culex pipiens and Culex restuans which are the primary mosquito species that transmit WNV. Starting in 2016, 25 fixed gravid sites were established mainly within the City of Pittsburgh. These traps were set weekly from May-September of each year. The data collected from these traps was used to determine when control efforts such as pesticide distribution were necessary. While the data is currently only used for surveillance purposes, it holds value for research as well. Many variables affect mosquito population density and WNV incidence, with precipitation and temperature being two of the most influential factors. These variables have the potential to increase the programs’ understanding of what is affecting WNV in Allegheny County. This study aimed to determine if there were any correlations between precipitation and/or temperature and mosquito population density and WNV positive samples from 2016-2022. While no significant correlations were found, it is important that research continues to examine these variables, as it may aid public health programs in their efforts against WNV. If vector control programs had the power of a localized predictive model for WNV severity based on variables like weather patterns, they would have a greater ability to proactively protect the public from the threat of WNV and other diseases