United States Eventing Association

Three California Counties Affected by Vesicular Stomatitis Outbreak

The United States Equestrian Federation (USEF) continues to monitor the outbreak of Vesicular Stomatitis (VS) in California. Currently, the United States Department of Agriculture (USDA) has confirmed that there are three counties—San Diego, San Bernardino, and Riverside—where confirmed or suspected cases of VS have been identified.

A USDA situation report dated June 2, 2023, states that there are 18 premises affected within those counties. To date, all confirmed cases have been vesicular stomatitis New Jersey virus serotype (VSNJV).

The 2023 VSV outbreak began on May 17 when the National Veterinary Services Laboratories (NVSL) in Ames, Iowa, confirmed the first VSV-positive premises in San Diego County, California.

According to the USDA, Vesicular Stomatitis is a viral disease that primarily affects horses, cattle, and swine. The agent that causes vesicular stomatitis, VSV, has a wide host range and can occasionally infect sheep and goats. It is not usually fatal, but there is no specific treatment or cure. Good sanitation and quarantine practices on affected farms can usually contain the infection.

The most common method of transmission is through biting insects such as Black flies, sand flies, and biting midges, but other insects may also be involved. Once the disease is introduced into a herd, it may move from animal to animal by contact or exposure to saliva or fluid from ruptured vesicles.

In horses, vesicular lesions generally occur on the upper surface of the tongue, lips, corners of the mouth, and gums, as well as around the nostrils. The lesions in horses may also appear as crusting scabs on the muzzle, lips, ears, coronary bands, sheath, udder, or underside of the abdomen. The lesions typically resolve within 14 days.

The USEF is monitoring the outbreak and supports continuing competitions in VS-affected states and competitions which include horses from VS-affected states provided biosecurity measures are implemented.

The USEF held a webinar on May 26 that was attended by over 300 participants.

Members can watch the webinar and review the information available here.

For any questions, please reach out to [email protected] or call 859-225-6991.