Transmission and epidemiology of bluetongue and epizootic hemorrhagic disease in North America: current perspectives, research gaps, and future directions

Authors: Ruder, Mark; LYSYK, TIMOTHY - Aafc Lethrdge Research Center; STALLKNECHT, DAVID - University Of Georgia; FOIL, LANE - Louisiana State University Agcenter; JOHNSON, DONNA - US Department Of Agriculture (USDA); CHASE, CHRISTOPHER - South Dakota State University; DARGATZ, DAVID - Animal And Plant Health Inspection Service (APHIS); GIBBS, E - University Of Florida

Submitted to: Vector-Borne and Zoonotic Diseases
Publication Type: Review Article
Publication Acceptance Date: 6/1/2015
Publication Date: 6/1/2015
Citation: Ruder, M.G., Lysyk, T.J., Stallknecht, D.E., Foil, L.D., Johnson, D.J., Chase, C.C., Dargatz, D.A., Gibbs, E.P. 2015. Transmission and epidemiology of bluetongue and epizootic hemorrhagic disease in North America: Current perspectives, research gaps, and future directions. Vector-Borne and Zoonotic Diseases. 15(6):348-363.

Interpretive Summary: Bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) are closely related viruses transmitted by small blood-feeding insects called Culicoides biting midges. These viruses infect a variety of domestic and wild ruminant hosts; however, the susceptibility to clinical disease associated with BTV or EHDV infection varies greatly among host species, as well as between individuals of the same species. In general, BTV primarily causes disease in sheep and sometimes cattle and other wild ruminants, whereas EHD is the most significant viral disease of white-tailed deer but also impacts cattle and some other wild ruminants. These viruses have circulated in the USA for over 60 years but recent changes in the patterns of infection and disease have forced the scientific community to revisit some fundamental areas of research related to the epidemiology of these diseases. In particular, the virus-Culicoides-ruminant interactions and the environmental conditions that drive disease patterns. The aim of this review is to identify research and surveillance gaps that obscure our understanding of BT and EHD in North America. Numerous reviews focusing on various aspects of BT and EHD epidemiology and pathobiology have been published and readers are referred to these papers for a comprehensive literature review. Here we focus on the North American perspective of recent BTV and EHDV events and the associated epidemiology research gaps.

Technical Abstract: Bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) are arthropod-transmitted viruses in the genus Orbivirus of the family Reoviridae. These viruses infect a variety of domestic and wild ruminant hosts, although the susceptibility to clinical disease associated with BTV or EHDV infection varies greatly among host species, as well as between individuals of the same species. Since their initial detection in North America during the 1950s, these viruses have circulated in endemic and epidemic patterns with occasional incursions to more northern latitudes. In recent years, changes in the pattern of BTV and EHDV infection and disease have forced the scientific community to revisit some fundamental areas related to the epidemiology of these diseases specifically in relation to virus-vector-host interactions and environmental factors that have potentially enabled the observed changes. The aim of this review is to identify research and surveillance gaps that obscure our understanding of BT and EHD in North America. Numerous reviews focusing on various aspects of BT and EHD epidemiology and pathobiology have been published and readers are referred to these papers for a comprehensive literature review. Here we focus on the North American perspective of recent Orbivirus events and the associated epidemiology research gaps.