Since Apr. 29, 490 premises in several midwestern and southwestern states have been confirmed positive, or suspected positive for Vesicular Stomatitis Virus (VSV), according to the USDA Animal and Plant Health Inspection Service (APHIS) this week.

The strain of virus is the New Jersey serotype, where confirmed, in eight states–Arizona, Colorado, Nebraska, New Mexico, South Dakota, Texas, Utah and Wyoming.


The outbreak was first detected in a horse (the index case) in Grant County, New Mexico.

APHIS has reported Fifty-two (52) new VSV-confirmed (New Jersey serotype) and/or suspect premises in Colorado, Nebraska and Wyoming have been identified and quarantined during the past week.

Currently, there are one hundred one (101) affected premises remaining under quarantine in 6 states (Colorado, Nebraska, New Mexico, South Dakota, Utah, and Wyoming).

The main symptoms of VSV are slobbering, blisters, sores and sloughing of skin in the mouth, on the tongue, on the muzzle, inside the ears and on the coronary band above the hooves. Lameness and weight loss may also occur. Flies and midges are the insect vectors responsible for transmitting VSV.

The virus can also be spread through direct contact with infected livestock and indirectly through contact with contaminated equipmentand tack. Fly and insect control is the most important step in preventing the disease. Good sanitation and bio-security measures can help avoid exposure.

VSV is particularly significant because it is clinically indistinguishable from foot-and-mouth disease (FMD), swine vesicular disease and vesicular exanthema of swine, all serious foreign animal diseases. Because of similarities to these diseases, it is essential to quickly determine a diagnosis with laboratory testing if vesicles are observed in non-equines. Of the vesicular diseases, VSV is the only one that affects horses, and the presence of lesions is suggestive of VSV.

Robert Herriman is a microbiologist and the Editor-in-Chief of Outbreak News Today and the Executive Editor of The Global Dispatch

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