Orbiviruses, such as those that cause bluetongue (BT) and epizootic hemorrhagic disease (EHD) have caused growing concerns among veterinarians and livestock producers. In response to the emergence of new serotypes, increased reports of spillover and clinical disease in cattle and increased spread and adaptation to new geographical areas, the United States Animal Health Association (USAHA) passed a resolution in 2012, requesting the USDA and the United States Department of Interior (DOI) organize a diverse panel of experts to determine research needs and identify and prioritize intervention strategies.
The agencies organized a “gap analysis workshop,” which took place in Manhattan, Kan., on May 14–16, 2013. This week, USDA released “Orbiviruses, Bluetongue and Epizootic Hemmorhagic Disease: Gap Analysis Workshop Report,” outlining the results of the workshop.
Workshop participants listed important countermeasures, and also identified several weaknesses that affect the ability to prevent and control disease outbreaks. Key points from the report include:
- Not every susceptible species will show disease following infection with all strains of these viruses, and virulence determinants of orbiviruses are not described, and hence the viruses cannot be monitored effectively. Comprehensive disease control strategies require basic research to determine these unknown aspects of the virus/host interaction.
- Modern virology methods and advances in technology offer promise for better understanding of these viruses, but significant gaps remain.
- There is a lack of understanding of the ecosystems supporting the arthropod transmission of BTV and EHDV in different climatic and geographic zones. There is a definite need for an active national surveillance program for these viruses, which would require consensus among national and State diagnostic laboratories.
- In general, sheep and cattle producers, veterinarians, and diagnosticians are not adequately informed about the clinical presentations of BT and EHD.
- There is a need to better understand the behavior of midge insects that serve as vectors of these diseases, along with a need for better insecticides, repellants, and kairomones to reduce biting attack rates.
- While a limited number of vaccines are available internationally for BTV, there are none for EHDV. The only fully licensed vaccines in the United States are attenuated, modified-live vaccines. Autogenous vaccines have been used in the captive cervid industry to immunize deer against EHDV and BTV infection with limited success.
Workshop participants developed a detailed list of recommendations including strategies for detecting threats early, responding rapidly and effectively, developing more effective vaccines and vaccination strategies and continued research to gain a better understanding of orbiviruses and the diseases they cause.
The full report is available online from USDA’s Agricultural Research Service.