Livestock producers in the United States should be cautious but not overly fearful of bluetongue virus, according to a veterinary laboratory director at Kansas State University.
Gary Anderson, director of the Veterinary Diagnostic Laboratory at K-State, said strains of the virus, which recently cropped up in the United Kingdom, can be found in Kansas and elsewhere in the United States.
“We are fortunate that bluetongue virus has many factors that must line up for it to cause significant disease,” Anderson said. “The strains of the virus that we have in the U.S. generally are not as virulent, or ‘hot,’ as some of the strains in other parts of the world.”
Bluetongue is a viral infection that most often infects sheep but also infects cattle, deer and other ruminants. The virus is transmitted by a small insect, a biting midge, that is susceptible to cold weather and freezing conditions. Anderson said that’s why animals in the U.S. are most susceptible during summer and fall, particularly animals in California and the southern part of the country.
Scientists at K-State’s Veterinary Diagnostic Laboratory are some of the more than 150 K-Staters actively working in the food safety and animal health arenas. The scientists at the Veterinary Diagnostic Laboratory routinely test for bluetongue. They use techniques certified by the U.S. Department of Agriculture and undergo proficiency testing each year.
“We know that bluetongue virus infections occur in Kansas because we see evidence of immune responsiveness to the virus in serum collected from animals,” Anderson said. “However, we seldom see the disease here.”
The symptoms of bluetongue virus are more apparent in sheep and deer. They include sores on the feet and in the mouth. The virus also can affect animals in poor condition and cause pregnant animals to abort. The symptoms often are not apparent in cattle. Bluetongue virus can increase susceptibility to other diseases, decrease the reproductive potential of the herd and make animals unacceptable for the food supply.
“Bluetongue virus is not infectious to humans; humans are not at risk of getting sick from meat or from contact with animals,” Anderson said. “Our food supply inspectors would not let an animal that is sick or in poor condition into our food supply.”
Bluetongue virus poses the greatest problems for producers in that it affects the import and export of livestock and that it could cause fetal abnormalities in breeding herds, Anderson said. Although scientists have been working on a vaccine, Anderson said that bluetongue virus has been difficult to control because of the way it’s transmitted.
“It is extremely difficult to manage the insect populations,” he said. “Scientists think that the virus arrived in Europe from South Africa by the way of strong trade winds blowing across the two continents. More recently, transcontinental transmission has likely occurred via the transport of infected animals. The animals arrive, and then the biting midges feed on them with subsequent transmission to susceptible herd mates or other animals.”
Anderson said that intervention strategies should focus on careful control of animals’ movements after appropriate testing.
“Producers and veterinarians must always be aware of sick animals, even ones that do not appear to be all that sick,” he said. “They should be aware of animals that have sores in their mouths and/or exhibit lameness, because the signs are similar to other diseases like foot and mouth disease that may be more significant and devastating than bluetongue virus.”