Arkansas: Horse Herd Tests Positive for Equine Infectious Anemia (EIA)

Here’s a press release from the government agriculture officials in the state of Arkansas. It is providing for public information in its entirety.

Another reason to hate horse flies: they transmit EIA from horse to horse. But they are only one mode of transmission. Horse fly photo by Davis Kwan.



LITTLE ROCK, AR, AUGUST 24, 2011–The State of Arkansas has had multiple positives for Equine Infectious Anemia (EIA) in the Clarksville, AR., area (Johnson County). Arkansas Livestock and Poultry Commission (ALPC) along with a local veterinarian are investigating the positive herd.

At present the infection seems to be isolated to the single herd. The owner of the herd does not show horses nor do they sell any horses to any extent. The index herd has only one adjacent herd and that herd is in the process of being tested today.

The source of the infection has not been found. The most recent addition to the index herd was traced back to its origin. Those horses had all negative EIA tests but were retested by Arkansas Livestock Poultry Commission personnel and all their horses were negative.

The number of positives horses in the index herd is substantial and alarming. Arkansas Livestock Poultry Commission is investigating all leads to make sure that this does not spread from the index herd.

Since the index herd has added horses over the years some of those horses may have been the source of infection. The herd has been quarantined from the time of the first positive and Arkansas Livestock Poultry Commission has a livestock inspector on the premises daily. There has not been any information that warrants canceling horse shows, etc., in Arkansas at the present time.


State of Arkansas contact: Dr. Pat Badley Phone: (501) 907-2400

About EIA, courtesy of USDA: EIA is an infectious and potentially fatal viral disease of horses. No vaccine or treatment exists for the disease. Clinical signs of EIA include fever, weight loss, icterus (yellowing of body tissues), anemia, swelling in the limbs, and weakness. However, not all equids infected with the equine infectious anemia virus (EIAV) show signs of illness, and these animals serve as inapparent carriers.

EIAV is usually transmitted from horse to horse by large biting insects such as horseflies and deerflies. The bites from these flies stimulate defensive movement by the horse, which often results in an interruption of the flies’ blood feeding. When interrupted, flies are motivated to complete feeding as soon as possible. They then attack the same or a second host and feed to complete their meal. In this manner, any infective material from the blood of the first host that is present on the mouthparts of the flies can be mechanically transmitted to the second host.

Needles and equipment contaminated with blood from an infected horse can also spread the virus when used on unexposed horses. Horses demonstrating clinical signs of EIA pose the greatest risk of spreading the virus because they have the greatest concentrations of circulating virus. However, even inapparent carriers pose a risk to other horses.

For more information, please download the complete EIA information sheet from the USDA website.




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