Over 130 researchers, scientists and veterinarians were on hand for the 2014 “Pestiviruses: Old Enemies, New Challenges” Symposium in late October in Kansas City, Mo. The conference focused on pestiviruses including classical swine fever virus, bovine viral diarrhea virus (BVDV) and emerging pestiviruses such as HoBi-like viruses. The Symposium represented the first time the US BVDV Meeting and the European Society for Veterinary Virology Society Pestivirus Symposium were merged for a joint meeting.

Participants from 10 countries were on hand to share the latest research on pestiviruses. The Symposium was divided into three different sessions that focused on the effect that pestivirus infections have on the immune systems, changes in pestiviruses that reduce the effectiveness of vaccines and diagnostics and the emergence of new pestiviruses. Two keynote addresses, one by Volker Moennig (Hannover School of Veterinary Medicine) and one by Dan Givens (Auburn University) addressed the control of BVDV. BVDV control programs are common in Europe and have proved to be very effective in reducing BVDV losses. In contrast, multistate, large scale, systematic BVDV control programs are not available in the US.

It is estimated that BVDV infections cost U.S. producers $400 million annually. BVDV can cause acute infections and even death in sick cattle, reproductive problems, reduced rate of gain or reduced milk production. Its insidious nature allows it to be transferred in utero to unborn calves, causing persistent infection (PI) which can lead to abortion and deformities, unthrifty calves or even seemingly normal calves that then will shed the virus during their lifetime. Controlling and/or eradicating BVDV involves vaccination, biosecurity, testing and removal of infected animals. Scientists are also studying the role wild ruminants such as deer have on the maintenance and spread of the BVDV virus.

European control programs have resulted in eradication of BVDV in several regions, but it took large scale cooperation and coordination among producers. Conference organizer Julia Ridpath, PhD, National Animal Disease Center, Ames, Iowa, says, “For eradication programs to work, the effort needs to be organized on a regional basis. Successful control programs cannot depend on vaccination alone but must include the detection and removal of infected animals.” While eradication takes time and effort, Ridpath notes that successful eradication programs are in effect for both BVDV and classical swine fever virus.

There are a variety of tests available to help in the detection of BVDV such as virus isolation, PCR, immunohistochemistry to identify PI cattle and more, but nothing is perfect at this point. Chris Chase, DVM, PhD, Dipl. ACVM, South Dakota State University, says, “The impact of BVDV on reproduction is under-estimated; developing a test to detect PI calves in utero would be a great advancement in controlling this disease.”

Chase says not only do we need to be vigilant about BVDV, but there are other new pestiviruses of ruminants that we have to be aware of and also be looking out for. These include HoBi-like viruses an emerging species of bovine pestivirus that causes clinical presentations in cattle indistinguishable from BVDV and pronghorn virus, an emerging species that has been found in be circulating in US wildlife herds.

The difficulty in getting a handle on BVDV is that regional approaches to disease control are at odds with the worldwide traffic in animal products and biologics, and controlling newly recognized pestiviruses such as the HoBi-like viruses is more effective when approached as a global challenge rather than any one nation’s problem.

Scientific papers from the Pestivirus symposium will be published in an upcoming Animal Health Research Reviews.

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