A Retrospective Study of the Influence of Climatic Variables on Hemorrhagic disease in North America

Hemorrhagic disease (HD) is primarily caused by two related arboviruses, bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV). HD affects domestic and wild ruminants and is transmitted by biting midges of the genus Culicoides. Therefore, distribution of the disease is dependent on the survival of the midge in an area. Outbreaks in the U.S. are more common in mid-summer to late autumn, which correlates to amount of vector activity, and will decrease after the first frost. HD is the most significant disease of wild ruminants in North America and is not treatable. Currently, HD is epidemic in the western US, but it could become endemic with increased vector survivability. Countries with endemic HD experience economic impacts such as trade restrictions and the cost of surveillance, testing, and vaccination. This project examines the role of changing weather patterns such as temperature and precipitation in the prevalence of HD in North American domestic and wild animals. Drawing on information from various scholarly journals, press releases, and data from the Wyoming State Veterinary Laboratory, it was found that factors such as drought and wind speed influence HD prevalence in an endemic area. In addition, increasing temperatures have allowed the vector to expand its range and have led to infections in naïve locations, usually at northern latitudes. This research shows that cases of HD will continue to reach new areas as climate patterns change, which poses issues such as animal health and economic consequences.