Ireland's EIA Experience: What Did We Learn?

In 2006, Ireland was rocked by an outbreak of equine infectious anemia (EIA) that was rapidly contained by veterinarians and the Irish Department of Agriculture, Fisheries and Food (read more). Despite their quick action, the fallout from this outbreak has been widespread. In the three years since the outbreak, veterinarians and scientists have been rehashing the course of events to learn everything possible about the outbreak so that other countries never have to live through the same experience.

EIA is caused by a lentivirus that belongs to retrovirus family along with the human immunodeficiency virus (HIV) and feline immunodeficiency virus.

EIA virus is spread through body secretions such as blood. EIA can be transmitted via biting insects such as the deer fly and horse fly as well as from tainted tack, equipment, and veterinary supplies, and from mares to foals during pregnancy.

"The most important mode of transmission, however, is by humans," explained Charles Issel, DVM, PhD, Dipl. ACVIM from the Gluck Equine Research Center at the University of Kentucky. Issel assisted veterinarians at the affected hospital to analyze medical records and determine the exact nature of the outbreak.

"A single drop of blood from an infected horse carried by man is capable of infecting about 10,000 times as many horses compared to the blood on the mouthparts of a contaminated horse fly," Issel continued.

In addition to the known routes of exposure, "air-borne transmission of EIA must be considered as a possible way that the virus can be transmitted from horse to horse," Issel said.

Issel and the other investigators hypothesize that aerosolized virus particles could have been rapidly disseminated between horses, resulting in the remarkably high rate of infection. If this hypothesis was true, however, Issel wonders why more horses have not become infected via this route of exposure over the years.

What should countries such as the United States learn from Ireland's EIA experience?

  • Test all horses for EIA to minimize potential spread of the disease;
  • Treat all horses and horse products as potentially infective;
  • Use closed system blood collection equipment that will prevent any blood transfer from the horse to the veterinarian;
  • Be aware that veterinary biological products such as equine plasma are not as stringently governed as human products and may be a source of various types of infections (plasma is routinely administered to foals in cases of failure of passive transfer and where Rhodococcus equi is endemic), and;
  • Equine hospitals should test all admissions for EIA, maintain suspect cases in strict isolation, maintain detailed hospital records, and if possible, attempt to maintain greater separation of both personnel and patients by space and time to reduce in-hospital transmission.

The EIA Ireland outbreak also demonstrates that the veterinary community needs an infection control system like human medicine to appropriately clean up body fluids.

More information regarding the Ireland EIA outbreak is available by searching the Ireland's Department of Agriculture, Fisheries and Food Web site, and in a full-length article titled, "Reducing the risks of infection in veterinary practices: Recent lessons learned with Equine Infectious Anemia (EIA)" authored by Issel and Michael Sadlier, MVB, CertES(Orth), CertESM, MACVSc(EqSurg), MRCVS from Troytown Veterinary Hospital.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.