Migratory raptors carry several diseases known to be harmful to humans and livestock, including West Nile virus (WNV) and Eastern Equine Encephalitis (EEE). The presence or absence of these diseases in migrating raptors has implications for the spread of disease globally. These raptors can travel thousands of miles during their annual migration and can therefore propagate these diseases over widespread areas. Acquiring a percentage of disease prevalence in these raptors can help epidemiologists identify how much migrating birds factor into disease transference, as well as, its possible impact on public health. By utilizing the raptor banding station in Cape May, New Jersey, 116 Hippoboscidae ectoparasites living on raptors were collected for molecular analysis. The flies contained a blood gorge from the bird that was used to detect WNV and EEE by reverse transcriptase PCR. Using an extrapolation model, the total number of infected raptors potentially carrying the pathogens was created. Additionally, the impact of hippoboscid flies living and feeding on the raptors was analyzed by comparing their body condition to the estimated number of flies on the birds. It was hypothesized that birds with more hippoboscid flies would have a diminished body condition.
During molecular analysis of the RNA from hippoboscid flies living on migratory raptors, WNV was detected in 5 out of 116 samples whereas EEE was not detected. Of the WNV positive birds, three were male Cooper’s Hawks and two were female Sharp Shinned Hawks captured in 2015. Using our results to estimate the potential infection rate across all Copper’s and Sharp Shinned Hawks banded at Cape May, NJ, we calculated 0.24% of Cooper’s Hawks and 0.28% of Sharp Shinned Hawks could be infected with WNV. These values were used to extrapolate the total number of infected raptors migrating through Cape May, NJ based on total hawk count data from this location throughout the 2015 fall migration. We suggest there are potentially 104 Cooper’s Hawks and 293 Sharp Shinned Hawks carrying WNV during their fall migration through this region. These hawks may carry WNV to warmer climates where disease vectors, such as mosquitoes, flourish and may aid in disease proliferation. Additionally, analysis of the relationship between birds’ body condition and the number of ectoparasites living on them indicated no significant correlation for male (R2 value = 0.0352, p = 0.26) or female (R2 value = 0.0125, p = 0.58) Cooper’s Hawks.