BROOMFIELD, Colo. (CBS4) — The Colorado Department of Agriculture pressed livestock owners for mandatory reporting Friday following confirmation of growing numbers of cases of a livestock virus that presently has no vaccine.

“We are seeing increasing numbers in new counties across the state,” said Colorado State Veterinarian Dr. Keith Roehr.

The state office referred to the increase as an “outbreak” and demanded that potential cases to be reported regardless of testing or treatment by livestock owners or veterinarians.

Presently, 32 Colorado counties have confirmed cases of vesicular stomatitis virus (VSV). The highest numbers of cases are in counties in the northern Front Range and the southwestern section of the state.

The first incidence of VSV n Colorado this year was found in Weld County on July 3. By early August, it had spread to 14 counties and 287 animals were reportedly quarantined.

Though rarely fatal, VSV alters animals’ food and water intake, sometimes leading severe cases of malnutrition, dehydration, and weight loss.

VSV primarily affects horses and cattle, but swine, sheep, goats, llamas, and alpacas have shown signs of exposure, according to the state office, which added that human risk increases with exposure to infected animals, but “it is rare” that people contract the disease. Human symptoms resemble those of a mild illness.

However, horses and cattle develop blisters and lesions around and inside their mouths, muzzles, tongues, and ears.

“Equine owners and livestock producers across the state are impacted by VSV,” a spokesperson wrote in the State Veterinarian’s Office’s press release. “All livestock owners should carefully watch the case numbers and affected counties to gauge their level of risk and institute mitigation measures.”

The office’s press release suggested livestock owners and managers of Colorado’s fairs and rodeos to consider instituting updated rules for health certification. It also requested owners cease sharing feed and health equipment between herd, and that they contact the states of destination if transporting across state lines.

Little is known about the spread of the disease, but insects are suspect. Black flies, sand flies, and biting midges gained mention, and fly management is among the recommended herd treatments.

The state’s table shows confirmed cases in Adams, Alamosa, Arapahoe, Archuleta, Boulder, Broomfield, Chaffee, Conejos, Delta, Dolores, Douglas, El Paso, Fremont, Garfield, Gilpin, Grand, Gunnison, Jefferson, La Plata, Larimer, Mesa, Mineral, Montezuma, Montrose, Morgan, Ouray, Park, Pueblo, Rio Blanco, San Miguel, Summit, and Weld counties. This table is updated regularly by the state.

More than 200 Colorado farms and stables were placed under quarantine during a VSV outbreak in the summer of 2014.