A case of equine piroplasmosis has been reported at a New Mexico racetrack. The affected horse, a Quarter Horse, has been euthanized.

The World Organization for Animal Health reported that the source of the outbreak was unknown. This outbreak involved a strain of the virus—Babesia caballi —that has not yet been seen, according to Veterinary Practice News. Last year’s outbreak, which began in Texas and affected more than 300 horses across 12 states, was caused by the Theileria equi bacteria.

The disease can be transmitted to horses, donkeys, mules and zebras through tick bites, as well as improperly disinfected needles and surgical supplies. Symptoms include poor appetite, fever, anemia, a swollen abdomen and breathing trouble. Affected horses may also suffer from edema.