Twenty horses on six premises in Florida had tested positive as of Sept. 8 for equine piroplasmosis, a bloodborne parasitic disease that last appeared in the United States two decades ago.
Two parasites, Babesia caballi and B. equi, cause equine piroplasmosis. Horses contract the disease primarily from ticks or contaminated needles. Signs of infection include depression, fever, anemia, icteric mucous membranes, and low platelet counts. Equine piroplasmosis also can cause roughened hair coats, constipation, and colic. In its milder form, the disease causes horses to appear weak and to lack appetite. Some horses become chronic carriers of piroplasmosis.
As of Sept. 8, Florida officials had quarantined 19 premises. Officials believe the disease has spread because of management practices that result in transfer of whole blood between horses. Ongoing tick surveillance has not identified any foreign ticks, and no domestic ticks have tested positive for the parasites that cause equine piroplasmosis.