According to the USDA-Animal and Plant Health Inspection Service (APHIS) vesicular stomatitis virus (VSV) has been confirmed in eight states this year: Arizona, Arkansas, Kansas, Missouri, Nebraska, New Mexico, Oklahoma and Texas.
Since the start of the outbreak, 323 VSV-affected premises have been identified (202 confirmed positive, 121 suspect), according to APHIS. Of these, 310 had only equine species clinically affected; 12 premises had clinically affected cattle (one premise is yet to be confirmed).
However, there have been no new VSV-positive states identified since July 27, 2020, according to the APHIS report issued on Sept. 3. The full report is available here: https://bit.ly/3jZoxCJ
Vesicular stomatitis is a viral disease that primarily affects horses and cattle and occasionally swine, sheep, goats, llamas and alpacas.
Because active cases have been identified this summer, state veterinarians encourage practitioners and livestock owners to be on the alert for suspect cases and to report them to their respective state office.
Other than this year, the most recent and largest VSV outbreak occurred in 2015. Outbreaks usually occur during the warmer months, often along waterways. The time from exposure to the onset of clinical signs is two to eight days, said Rod Hall, Oklahoma state veterinarian, in a news release.
Hall said, "Please make your clients aware that livestock or horses traveling from a county that has had VSV diagnosed within the past 30 days or a county that contains premises quarantined for vesicular stomatitis need to be accompanied by a certificate of veterinary inspection dated within five days of entry and contain this statement: “All animals identified on this certificate of veterinary inspection have been examined and found to be free from signs of vesicular stomatitis and have not originated from a premise which is under quarantine for vesicular stomatitis. Please be on the lookout for symptoms of the disease and let us know if you see livestock or horses with symptoms."
Humans can become infected with the disease when handling affected animals, but this is a rare event. VSV can cause flu-like symptoms if infected saliva gets into an open wound, eyes, or mouth, according to the news release. People handling potentially infected animals should wear gloves for protection and talk with a physician if they have questions.
The 2020 VSV outbreak began on April 13, 2020, when the National Veterinary Services Laboratories (NVSL) in Ames, Iowa confirmed the first VSV-positive premises in Dona Ana County, New Mexico.
The virus usually runs its course in five to seven days, and it can take up to an additional seven days for the infected animal to recover from the symptoms. There are no approved vaccines for VSV.
Because insects are the primary source of infection, the best way to combat the virus spread is to take aggressive steps to limit exposure to biting flies, ticks and midges. The virus can also be spread by nose-to-nose contact between animals. Establish insect control measures that consider the animal as well as the area the livestock reside in.
Vesicular stomatitis does not normally kill affected animals, but it can cause economic losses for livestock producers by preventing animal movements and impacting international trade. Farms with affected animals are quarantined until 14 days after lesions appear on the last case at that location.
Quarantine periods can be lengthy if the disease continues to spread within the premises. Quarantines are not lifted until a veterinarian has examined all susceptible animals on the premises.
The first sign of illness is often excessive salivation, caused by the lesions in the mouth, according to Wendie Powell, Kansas State University Extension specialist. The blisters will swell and break open, which causes mouth pain, discomfort, and reluctance to eat or drink, leading to severe weight loss. Lesions or scabs will appear on the muzzle, lips, ears, coronary bands and ventral abdomen. If the coronary bands of the hooves are affected, then lameness can occur. A spike in body temperature before or at the same time lesions ﬁrst appear can be noticed. This is a painful virus and can be costly to manage.