Map of VSV cases in the United States.
Map of VSV cases in the United States. Image via USDA

By Miriam Raftery

Fifteen properties in San Diego County are under quarantine by the U.S. Department of Agriculture after six cases of vesicular stomatitis virus have been confirmed in San Diego County, according to the USDA.

Testing is under way on another nine suspected San Diego cases.

Two confirmed cases and two suspected cases are in Riverside County, where four properties are quarantined. These are the only areas in the United States with current cases of VSV.

The first local case in this outbreak occurred May 17 in Ramona, according to The San Diego Union-Tribune.

While all of the local cases so far are in horses, the disease can also afflict donkeys, cattle, pigs, sheep, goats, llamas, alpacas or other hooved livestock.

The quarantines will last at least 14 days after the last known case. However blisters on mouths and hooves can take up to two months to resolve.

The quarantines mean no transporting animals to or from the impacted properties will be allowed until a veterinarian has cleared animals for travel.

Chart showing VSV cases in the region.
Chart showing VSV cases in the region. Image via USDA

Some states and livestock events such as horse shows may prohibit animals from the impacted areas from taking part even if there is no known exposure, so check with show organizers before traveling to any livestock event.

The disease is spread by biting insects, primarily flies, so fly control is important.

But it can also spread through shared feeding or water troughs, and through commonly touched surfaces. Humans can also contract the virus by touching infected animals, so people are advise to wear gloves if handling the mouth, nose or hooves of livestock.

In livestock, the diseases causes severe blister-like lesions that are painful and often cause animals to stop eating and lose weight, forming crusty scabs, but it is rarely fatal. It can also cause temporary lameness.

No vaccine exists, but VSV can be treated with anti-inflammatory drugs. Secondary infections may require antibiotics.

If an animal has trouble eating, softening grain in warm water may be helpful, or using hay cubes softened in water to help afflicted horses.

In humans, the disease cause flu-like symptoms such as fever, muscle aches, headache and malaise.

The USDA advises people disinfect their hands and boots after handling an animal suspected of having the disease, and also change and wash clothes.

Miriam Raftery is editor of East County Magazine, where a version of this report originally appeared. East County Magazine is a member of the San Diego Online News Association.