Response from Secretary Vilsack and CEM Outbreak Update

Response from Secretary Vilsack

In May 2009 the American Horse Council sent a letter to the U.S. Secretary of Agriculture Tom Vilsack expressing our concern over the current outbreak of Contagious Equine Metritis (CEM), and the need for the investigation to be completed and for the U.S. to return to a CEM free status.  Secretary Vilsack responded in a letter to the AHC, stating that USDA is working aggressively to complete the investigation and protocols needed for a successful eradication. 

CEM Outbreak Update

Since the first discovery of a CEM positive stallion in December 2008, a total of 21 stallions (including one that is now a gelding) and five mares have been confirmed as positive for CEM.  None of the positive horses have yet been identified as the source of the outbreak; the epidemiologic investigation continues in an effort to determine the origin of this outbreak, but no conclusions can yet be drawn.

In addition to the 21 positive stallions and 5 positive mares, another 960 horses have been exposed to CEM. The total 986 horses have been found in 48 States. Hawaii and Rhode Island are the only States in which an exposed or positive horse has not been found.  The 21 positive stallions were found in 7 States: 1 in Georgia, 3 in Illinois, 3 in Indiana, 1 in Iowa, 4 in Kentucky, 1 in Texas, and 8 in Wisconsin. The five positive mares were found in three States: two in California, two in Illinois, and one in Wisconsin. All positive horses, and all exposed horses that have not yet completed testing and treatment protocols, are currently under quarantine or hold orders.

Of the 272 stallions, 169 (62%) have now completed their entire testing and treatment protocol and have been determined to be negative for CEM. Of the 169 that are now negative, 155 were exposed stallions and 14 were stallions that had previously tested positive. Those 14 stallions, including 4 from Kentucky, 3 from Indiana, 3 from Wisconsin, 2 from Illinois, 1 from Georgia, and 1 from Texas, are now free of CEM after being treated and re-tested. Another 55 exposed stallions are negative on their initial sampling cultures but have additional testing requirements to complete before being declared free.

Of the 714 mares, a total of 640 (90%) have completed testing and treatment and are negative for CEM; that total includes four formerly positive mares, two in California and two in Illinois, that have completed their treatment and testing protocols and are now negative.

Overall, 809 (82%) of the 986 horses involved are now known to be free of CEM. Three of the eight States that have had a positive horse, Georgia, Indiana, and Kentucky, have completed testing and treatment of all known positive and exposed horses and are considered free of CEM at this time.

The investigation of this outbreak has determined that all four of the positive Kentucky stallions were on the central Kentucky premises during the 2008 breeding season. The Texas and Indiana stallions also spent time on the Kentucky premises during 2008. The positive Wisconsin stallions were not in Kentucky, but four of them were co-located during at least one breeding season in Wisconsin with a positive stallion that was on the Kentucky premises in 2008. The fifth, sixth, seventh, and eighth Wisconsin stallions all spent time at the same breeding facility used by the fourth positive Wisconsin stallion, by the three positive Illinois stallions, and by the Iowa stallion. The Iowa stallion has since been gelded. The positive Georgia stallion was co-located with three positive Wisconsin stallions in 2008.

The positive Wisconsin mare was bred by the second positive stallion in Wisconsin. Each of the positive mares in Illinois and in California was bred by artificial insemination (AI) in 2008 using semen from a positive stallion. Both California mares were exposed by AI to the first positive stallion in Wisconsin and the first Illinois mare was exposed to a positive stallion now in Indiana. The second positive mare in Illinois was exposed by AI in 2008 to the second positive Illinois stallion.

What is CEM?

Contagious Equine Metritis is a transmissible, venereal, foreign animal disease in horses caused by a bacteria Taylorella equigenitalis. A CEM infection usually results in infertility in mares and, on rare occasions, can cause mares to spontaneously abort. Infected stallions exhibit no clinical signs. Stallions and mares can become chronic carriers of CEM and be sources of infection for future outbreaks. The transmission rate is high and naturally occurs by mating, but contaminated instruments and equipment may be an indirect source of infecting horses. The bacteria can also be spread via semen collected for artificial insemination.

CEM can be treated with disinfectants and antibiotics. CEM-positive mares, and mares from CEM-positive countries, are required to go through a treatment protocol and remain in quarantine for no less than 21 days. Stallions that have CEM or come from a CEM-positive country are required to remain quarantined until a treatment protocol is completed and they test negative for the disease.