Plan for a Long Term Investigation of Human Exposure to West Nile Virus in Fremont County, Wyoming, A

West Nile Virus (WNV) was originally discovered in Uganda in 1937. WNV belongs to the Flaviviridae family and is in the same genus as Dengue Fever, Zika virus, and Yellow Fever. Flaviviruses are persistently emerging and of great concern globally. Individuals contracting WNV may be asymptomatic, experience mild symptoms of fever, malaise, or develop a severe disabling illness such as meningitis, encephalitis, or polio-like paralysis. WNV was first detected in the U.S. in 1999, and rapidly migrated to the West Coast over the course of ten years reaching epidemic proportions in Wyoming in 2007. The majority of these cases were found in Fremont County with 118 infected, twelve neuroinvasive cases, and one death. Its persistence in Fremont County is evident from our testing of the vector Culex tarsalis mosquitoes and from our human serosurveys in 2011 and 2012. Interestingly, our previous serosurveys in 2011 and 2012 identified three subjects with abnormally high levels of IgM antibodies at least five years after self-reported initial infection. This coincides with similar observations from other serosurveys. This interesting humoral response to WNV is currently of great interest. Our proposed investigation will conduct a longitudinal study to identify and track subjects infected or previously exposed to WNV with the specific goal of identifying additional subjects expressing high levels of IgM long after initial exposure. It is planned to observe the seroconversion in these subjects to gain insight into this phenomenon. We also plan to test these individuals for cryptic infection through reverse transcriptase PCR.