Management practices suspected in spread of equine piroplasmosis cases in Florida

Tallahassee, Fla. — Florida officials say they are reaching out to owners of horses that compete in unregulated racing on dirt tracks, in an effort to prevent the spread of equine piroplasmosis (EP) among horses in that community.

At press time, at least 15 of nearly 170 horses tested positive for EP in five counties, down from 20 positives a week earlier.

The positive horses were on six premises out of 19 that were under quarantine, but the quarantine on four premises was lifted Sept. 15.

The state's Department of Agriculture and Consumer Services (DOACS) reported the first case Aug. 15 in Manatee County, near Bradenton, with others occurring later in Polk, Dade, DeSoto and Lake Counties.

"All the horses testing positive are closely linked via movement and common premises. Because there is a close association between all 20 positive horses, the spread of the disease is believed to be due to management practices that result in the transfer of whole blood between horses," according to an announcement from the office of Charles H. Bronson, DOACS commissioner.

EP is caused by the parasites Babesia caballi and T. equi, usually carried by ticks, but the organisms also can be passed by means of shared needles and syringes, and that's what officials believe is occurring in Florida. Tick surveillance turned up none that tested positive.

"The quarantined premises are ranches or stables housing Quarter Horses that participate in unregulated or unsanctioned races on dirt tracks. There's a lot of mingling and common stabling and the common use of syringes and needles. That's how they've all been related, and why we're reaching out to them to help put a stop to this," Terry McElroy, a spokesman for Bronson's office, tells DVM Newsmagazine.

There are no state restrictions on the movement or sale of Florida horses, but Canadian officials notified the U.S. Department of Agriculture it would no longer accept horses from Florida. The Florida state veterinarian's office is working to have that ban removed or modified.

The United States has been considered free of EP since 1982, but the causative organisms are endemic in 90 percent of the world. The only other countries where it is not considered endemic are Canada, Australia, Japan, England and Ireland.