At the Biosecurity: Our Regional & National Response symposium on Monday in Kansas City, Mo., Barbara Drolet, PhD, USDA, ARS, Arthropod-Borne Animal Diseases Research Unit, gave an update on exotic bluetongue.
Exotic bluetongues are spreading in countries, she said. It’s a non-contagious disease of ruminants, camelids and wildlife transmitted by Culicoides vectors.
Disease in sheep can have 100% morbidity and 50% mortality, with many clinical signs including a cyanotic blue tongue from throat swelling.
It’s less severe in cattle with reddening on the face/muzzle, abortions, lowered production efficiencies, mastitis and secondary infections.
Since 2006 six serotypes of bluetongue have shown up in Europe. In the U.S. we have had eight serotypes in the Southeast, and Drolet says we are not immune to having more serotypes come in.
In 2006, The Netherlands had a case of BTV-8 confirmed. It has spread to other European countries to 2,000 premises, and by 2007 there were 50,000 cases in countries considered bluetongue free zone until the outbreak. The vector is moving, said Drolet, and this is considered to be from climatic changes.
We have to worry about the domestic serotypes, some of which can be severe, Drolet said. In 2007 an outbreak in Wyoming and Montana resulted in 900 cases, and 300 animal deaths. “We need to worry about exotics and the serotypes that are already here,” Drolet warned.
Research gaps for bluetongue include identifying which Culicoides will transmit which serotypes and how diagnostic labs will determine if it’s virulent. There is no cross-protection in vaccines.
Drolet says they are looking at the European strain of BTV-8 because it’s so virulent, but the sheep studies and wildlife studies are not nearly as far along as hoped. “It took 15 months to get permits from APHIS to get the virus here into high-containment lab at Colorado State University,” she said. “How can we make progress like this?”
Production losses and trade restrictions can cause an estimated loss of $120 million a year in the U.S., and worldwide $3 billion a year.
“This is absolutely a threat to the U.S.,” Drolet warned. “We can’t regulate viruses. If they are deemed no longer exotic and instead domestic, it will open up research capabilities. This is a transboundary disease – it needs to be tackled on an international level.”