The outbreak of vesicular stomatitis (VS) that led to quarantine of livestock operations in three states last summer has slowly died out as cold weather removes the insect vectors that carry the virus. The USDA's Animal and Plant Health Inspection Service (APHIS) and State Departments of Agriculture have completed their comprehensive epidemiological investigation of this vesicular stomatitis virus (VSV) event and issued a final report indicating no new cases of VSV have been reported since early December 2014. All premises previously under quarantine in Nebraska and Texas have been released. All the remaining premises under quarantine in Colorado will be released 21 days after lesions of all affected animals on the premises have healed.
As of December 24 2014, a total of 433 VS-positive premises were confirmed in three U.S. states; Colorado with 370 premises, Nebraska with one premises and Texas with 62 premises according to the USDA's latest situation report.
Of the 433 total VS-positive premises, 403 were positive equine premises, 27 were positive bovine premises, and three premises had both cattle and horses positive.
Positive premises are eligible for quarantine release 21 days after lesions have healed in all affected animals. As of December 22, 2014, all confirmed VSV-positive premises in Nebraska have been released from quarantine. To date, 355 premises in Colorado have been released from quarantine and there are an additional 10 premises in Colorado on 21-day countdown to quarantine release.
Vesicular stomatitis virus (VSV) is classified as a rhabdovirus, and there are two serotypes of VSV – New Jersey and Indiana. Outbreaks this year have involved the New Jersey serotype. Infection with one serotype is not cross-protective for the second serotype. Clinical signs of VS, which can affect equines, cattle, bison, sheep, goats, pigs and camelids include vesicles, erosions, and sloughing of the skin on the muzzle, tongue, teats and above the hooves.
Insect vectors are the primary source of transmission of VS although mechanical transmission occurs in some species. Fly control is a key component in preventing spread of the virus.
Rarely, VS can affect humans, typically those who are in contact with infected animals. In humans the disease typically causes flu-like symptoms.