Research in Horses Shows Parasite that Causes Babesiosis Can Be Eliminated

Many countries in the world outside of the United States are home to the parasite Babesia caballi, which can cause illness or death in horses. Some infected horses might recover and become inapparent carriers of the parasite.

According to a recent study high doses of imidocarb dipropionate eliminated the parasite Babesia caballi in infected horses.

B. caballi causes a disease called babesiosis. Although babesiosis is considered an exotic disease among horses in the United States, it is common in other countries. Horses imported from a country with Babesia to a country without Babesia (such as the United States), must test negative for infection with the parasite before it can enter the country.

"If owners or breeders wish to import a B. caballi-positive horse into the United States, imidocarb treatment at the dosages reported in our manuscript is a potential option to attempt clearance of infection and make it possible to import the horse," said Donald P. Knowles, DVM, PhD, Dipl. ACVP, research leader of the Animal Disease Research Unit, of the Agricultural Research Service, USDA and adjunct professor at Washington State University.

Babesia can be a deadly infection in horses; therefore, countries without the parasite want to keep it away from their horse populations. Horses infected with Babesia can respond to the parasite in several ways. Some animals succumb to infection and die, but others survive and become persistently infected. These horses have no clinical signs of disease, but they still harbor the parasite and could become a source of infection to other horses.

To legally import an infected horse into countries free of infection, the parasite must first be eliminated from the persistently infected horse, Knowles said.

The researchers tested imidocarb because they knew it could control B. caballi replication, but there was some question about its ability to clear horses of infection.

"This study shows that, at least with the strain of B. caballi used in the study, it is possible to eliminate B. caballi infection from some horses and remove their risk of transmission," Knowles said.

However, he added, "Imidocarb can be toxic to horses and so treatment needs to be monitored closely."

The study, "Imidocarb dipropionate clears persistent Babesia caballi infection with elimination of transmission potential," was published in July online ahead of print in Antimicrobial Agents and Chemotherapy.

The abstract is available on PubMed.

About the Author

Marie Rosenthal, MS

Stay on top of the most recent Horse Health news with FREE weekly newsletters from Learn More

Free Newsletters

Sign up for the latest in:

From our partners