U.S. Department of Agriculture health officials confirmed 334 cases of Equine Piroplasmosis, Theileria equi, in 12 states. According to the Nov. 23 USDA Animal Plant Health Inspection Service report, health officials have quarantined all infected horses and confirmed all cases are linked to the original outbreak on a Texas ranch.
Scientists are still studying transmission, ticks and other potential exposed horses.
On Nov. 9, New Jersey Secretary of Agriculture Douglas H. Fisher asked veterinarians and horse owners to watch for signs of EP after two New Jersey horses, who were purchased in Texas, tested positive for the disease. Other cases have popped up in Alabama, California, Florida, Georgia, Louisiana, Minnesota, North Carolina, New Jersey, Tennessee, Utah and Wisconsin.
In October, Dr. John Clifford, Deputy Administrator with the USDA, confirmed a positive case of EP on a ranch in Kleberg County, Texas, and 31 other linked cases in Texas. Investigators collected ticks from five horses for testing and species identification however; they have not concluded the origin of the infection.
Equine Piroplasmosis is caused by two parasitic organisms, Babesia equi and Babesia caballi, and is primarily transmitted by the tropical horse tick, Dermacentor nitens, although contaminated needles may also spread the blood borne disease. In tests, the winter tick, American tick and tropical cattle tick have transmitted EP.
An infected equine may shows signs of fever, anemia, jaundiced mucous membranes, swollen abdomen and labored breathing, as late as 7 to 22 days after infection. Piroplasmosis may also cause roughened hair coats, constipation, colic, weakness and lack of appetite and hemoglorinuria—a condition that gives urine a red color.
As of August 2009, United States was not considered an endemic area, along with Canada, Australia, Japan, England and Ireland. Piroplasmosis is present in South and Center America, the Caribbean, Africa, the Middle East and parts of Europe.
EP first appeared in the United States in 1960 in a backyard horse in Florida. State and federal authorities launched an eradication program, which eliminated the disease in 1988.
The disease appeared again in August 2008. Florida's Department of Agriculture and Consumer Services officials quarantined 25 premises, tested more than 200 horses and euthanized 20 infected horses before declaring the incident resolved in February 2009.
However EP cases appeared in Missouri and Kansas in June, causing veterinarians to euthanize five positive horses. According to a USDA report, needle sharing between horses was responsible for spreading the disease, not ticks. Health officials then released all quarantines and closed the case.
During that case, three of the positive horses in Missouri were illegally removed from quarantine and possibly transported out of the country.