Evidence of Active Orbivirus Transmission in 2016 in Kansas and Nebraska

Authors: MCVEY, SCOTT - University Of Nebraska; HANZLICEK, GREG - Kansas State University; RUDER, MARK - University Of Georgia; LOY, DUSTIN - University Of Nebraska; Drolet, Barbara

Submitted to: Vector-Borne and Zoonotic Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/3/2024
Publication Date: 6/24/2024
Citation: Mcvey, S., Hanzlicek, G., Ruder, M., Loy, D., Drolet, B.S. 2024. Evidence of Active Orbivirus Transmission in 2016 in Kansas and Nebraska. Vector-Borne and Zoonotic Diseases. 24(6). https://doi.org/10.1089/vbz.2022.0096.
DOI: https://doi.org/10.1089/vbz.2022.0096

Interpretive Summary: Bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) are transmitted by biting midges and cause disease in cattle, sheep, and white tailed deer. Due to regulatory/trade restrictions, cattle and sheep must receive health checks and be negative for BTV. BTV and EHDV infected cattle can have very mild or no clinical disease. Therefore, observable clinical disease cannot be used to accurately determine whether virus is circulating within a herd. Retrospective serological and case diagnostic data of endemic levels of BTV and EHDV provide evidence of viral transmission among livestock and wildlife from 2016 in Kansas and Nebraska, a year when no clinical cases were reported for either state. Serological testing of mature cattle in nine distinct regional zones of Kansas revealed 76% to 100% had detectable antibodies to BTV and/or EHDV. Although no livestock cases were reported, low disease incidence in white-tailed deer and other susceptible wild ungulates was reported in 2016. Our results show significant BTV and EHDV transmission occurred in cattle in the absence of clinical cases in cattle or sheep. The factors that result in years of significant clinical disease in livestock and wildlife populations remain undefined. Additional retrospective studies are needed to determine whether this is a typical endemic virus circulation level for any given year in these states.

Technical Abstract: Retrospective serological and case diagnostic data of endemic bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) provide evidence of viral transmission among livestock and wildlife from 2016 in Kansas and Nebraska. Serological testing of mature cattle in nine distinct regional zones of Kansas revealed 76% to 100% had detectable antibodies to BTV and/or EHDV. Specimens tested in the Kansas Veterinary Diagnostic Laboratory (55 submissions) were 51% test-positive for antibodies to BTV and/or EHDV. Specimens tested in the Nebraska Veterinary Diagnostic Center (283 submissions) were 25% test-positive for antibodies to BTV and/or EHDV. Low disease incidence in white-tailed deer and other susceptible wild ungulates was observed during 2016. However, there were no confirmed reports of disease in livestock in either state. The reasons for emergence of significant clinical disease in livestock and wildlife populations remain undefined.