U.S. updating response plan for equid, ruminant diseases

Plum Island, N.Y.

-- The risk of African horse sickness virus (AHSV) and bluetongue virus (BT) entering the United States is considered low, but the USDA's Animal and Plant Health Inspection Service (APHIS) is rewriting the nation's emergency response plans, saying pathways do exist for them to enter the country.

AHS, which attacks all equids, is the most lethal infectious disease known to horses, with mortality as high as 95 percent, while bluetongue virus attacks ruminants. Both viruses are spread by certain species of Culicoides biting midges.

After the vector spread from Africa to northern Europe in 2006-2007, causing as many as 45,000 cases of BT in ruminants there, the U.S. equine industry asked APHIS to produce a white paper on potential pathways for the diseases in the United States.

The paper written by William R. White, BVSc., MPH, senior staff veterinarian for APHIS at the Foreign Animal Disease Diagnostic Laboratory at Plum Island Animal Disease Center in New York, was published in the April 2009 issue of Equine Disease Quarterly, a publication of Kentucky State University's Gluck Equine Research Center.

If the vector could carry BT from Africa to Europe, it might also carry AHS there, prompting Europe to prepare for that contingency now by stockpiling AHS vaccines, White says. The United States, he says, has a different but competent midge vector for AHS, which transmits some strains of BT in parts of the country. Both the equine industry and government agencies are watching closely to see if AHS does move north from Africa to Europe, White says.

Meanwhile, the U.S. emergency response plan is being updated.