eia in colorado

On Sept. 28, the Colorado Department of Agriculture (CDA) State Veterinarian’s Office received notice that another horse in that state has tested positive for equine infectious anemia (EIA).

This case (Case 2) follows reports from last month that an EIA-positive horse from Weld County had potentially exposed more than 200 other horses across the country to the virus (Case 1, the index case); Case 1 remains under investigation. While the newly confirmed case is also from Weld County, officials say it is unrelated to the index case. As of Sept. 20, there have only been two confirmed cases of EIA in Colorado horses.

“While the investigation is in its initial stages, it is clear the affected horse is unrelated to horses, locations, or movements to the previous case in 2018 (Case 1),” said State Veterinarian Keith Roehr, DVM. “The affected horse and other horses on the second Weld County property (from Case 2) are subject to a quarantine, which restricts movement of any horses on or off the property. The remaining horses on the facility will be observed, tested, and then retested in 60 days.

“It is important to note that the risk of disease transmission to other horses in Colorado at this time is low, due to the fact that there are not any horses housed on adjacent properties, which also lowers the risk of biting horse flies in the area,” he added.

The CDA also provided an update on the index case investigation through the Equine Disease Communication Center (EDCC) on Sept. 27. According to statement on the EDCC website:

  • The index premises in Weld County is under a quarantine order; two associated premises are under hold orders.
  • The 124 exposed horses under quarantine on the index premises tested negative for EIA on Sept. 10. They will be retested on or after Oct. 19, 60 days after last exposure to the index case.
  • 138 exposed horses have been located in Colorado (out of approximately 152 the CDA expect to be in the state).
  • 61 premises are under hold orders in 24 Colorado counties: Adams, Arapahoe, Archuleta, Boulder, Costilla, Crowley, Delta, Douglas, Eagle, Elbert, El Paso, Fremont, Gilpin, Gunnison, Huerfano, Jefferson, Larimer, Mesa, Moffat, Montrose, Morgan, Phillips, Sedgwick, and Weld.
  • Five premises have been released from hold after the 60-day retests were completed for all exposed horse(s) on those premises and found to be negative.
  • 72 exposed horses have been positively identified in 12 other states (out of approximately 83 the CDA expect to be out-of-state): Arizona, Idaho, Kentucky, Louisiana, Maine, Missouri, Nebraska, Nevada, Oklahoma, Tennessee, Texas, and Wyoming.
  • Many of the exposed horses will be eligible for their final 60-day retest over the next three weeks. The CDA said it has informed owners of exposed horses to work with their veterinarians to get the retesting done after the date stated on their hold orders. The date varies depending on the last date that their horse was exposed to the EIA-positive horse. At this time only exposed horses need to be tested, not all horses residing on the premises under the hold order.
  • Once the CDA receives the negative 60-day retest results it will release the hold order as quickly as possible so please notify the office with the results. If you have any questions, contact the state veterinarian’s office at 303/869-9130 or animalhealth@state.co.us.

EIA 101

Equine infectious anemia is a viral disease that attacks horses’ immune systems. The virus is transmitted through the exchange of body fluids from an infected to a uninfected animal, often by blood-feeding insects such as horseflies. It can also be transmitted through the use of blood-contaminated instruments or needles.

A Coggins test screens horses’ blood for antibodies that are indicative of the presence of EIA. Most U.S. states require horses to have proof of a negative Coggins test in order to travel.

Once an animal is infected with EIA, it is infected for life and can be a reservoir for the spread of disease. Not all horses show signs of disease, but those that do can exhibit:

  • Progressive condition loss;
  • Muscle weakness;
  • Poor stamina;
  • Fever;
  • Depression; and
  • Anemia.

There is no vaccine and no cure. A horse diagnosed with EIA dies, is euthanized, or must be placed under extremely strict quarantine conditions (at least 200 yards away from unaffected equids) for the rest of his life.