American Horse Council Press Release

USDA Re-implements cELISA Test for Equine Piroplamosis

On August 17, 2005, the U.S. Department of Agriculture re-implemented use of the competitive Enzyme-Linked Immunosorbent Assay (cELISA) test to determine whether horses imported into the U.S. are affected with Equine Piroplasmosis. To date, there have been few difficulties with the new test, although a slightly higher number of positive results have been reported, particularly along the border with Mexico.

“An increase in the number of horses found to be positive is expected. The cELISA test is a more sensitive test than the Complement Fixation test (CFT),” says Dr. Peter Timoney of the Gluck Equine Research Center in Lexington, Kentucky.

The cELISA has an accuracy rate of 98%, which means that two out of every one hundred horses will have questionable test results. The CFT is less sensitive, achieving reliable results only about 60% of the time.

USDA had implemented the cELISA late last year 2004 but several problems at the National Veterinary Services Laboratory, where the test is run, resulted in numerous false positive results. After significant pressure from the American Horse Council and others, the USDA rescinded use of the test.

On August 16, 2005, USDA’s Center for Veterinary Biologics licensed a commercial cELISA kit for piroplasmosis. The test kit, which has been in use worldwide for some time, is now being used by NVSL. The American Horse Council had requested that the commercial test kit be used when testing imported horses for piroplasmosis.