Q: I've recently heard that a Coggins test is not necessary. I'd also like some current facts on Equine Infection Anemia (EIA) and its risk to my horses.
A: First of all, a Coggins test, named after the virologist who developed the test, Leroy Coggins, tests for EIA. Many labs are now using a simpler ELISA test for EIA. EIA, also known as Swamp Fever, must be federally reported. There is no treatment, or vaccine. That is why there are laws requiring testing for public exhibition or interstate transportation. The virus is like HIV in humans, but is primarily transmitted by biting flies.
The best way to limit the spread of EIA is through annual testing of all horses, and immediate testing of any horse that shows signs compatible with the disease (fever, blood spots on mucous membranes, swelling of limbs, anemia). Horses with acute EIA have very high levels of virus in its blood, enough that one teaspoon has enough virus to infect thousands of horses. The asymptomatic (showing no signs) horse has much lower levels of virus in their blood, but still poses a risk to nearby horses.
The number of positive horses in Minnesota, by county, is available at the Minnesota Board of Animal Health website. The majority of these cases were identified by routine testing. In Minnesota in 2005, 5 horses tested positive out of 47,118 samples. Minnesota has had several years in the last ten where the positive cases were in the double digits. Several states, such as Arkansas and Texas, have had very active campaigns to reduce EIA cases. These testing programs have been successful in reducing the numbers of EIA cases and need to be continued.
Testing for EIA IS NECESSARY (via a Coggins test) to track and help contain the disease. It is recommended that all horses be tested annually for EIA. Testing is mandatory for horses being transported across state lines and attending certain shows or group events.
By Julie Wilson, DVM, University of Minnesota