This disease is a disease of Equidae (horses, donkeys, mules, and zebras), and is caused by two parasitic organisms, Babesia equi and Babesia caballi. Although, Equine Piroplasmosis is primarily transmitted to horses by ticks, this bloodborne disease has been spread mechanically from animal to animal by contaminated needles.

Once infected, an equine can take 7 to 22 days to show signs of illness. Cases of Equine Piroplasmosis can be mild or acute, depending on the virulence of the parasite. Acutely affected equine can have fever, anemia, jaundiced mucous membranes, swollen abdomens, and labored breathing. Equine Piroplasmosis can also cause equine to have roughened hair coats, constipation, and colic. In its milder form, Equine Piroplasmosis causes equine to appear weak and show lack of appetite.

The greatest risk for introduction of this disease is through trading of animals or international equestrian sports, where infected and non-infected animals are in contact. Many disease free countries have the climate suitable for a foreign tick vector, or have ticks which could act as vectors.