Given the current state of affairs in the equine world, it is time to talk about Equine Infectious Anemia (EIA). Maybe you think you have never heard of it? What about a Coggins test? Every horse that travels is required to have one and EIA is exactly what the test is for.
So, what is it? EIA, also known as "Swamp Fever", is a viral disease that affects horses, mules and donkeys. One of the most troubling things about EIA is that many affected individuals are asymptomatic. For those who do show signs, they will include but not limit themselves to fever, anemia, decreased appetite and sometimes even sudden death. More symptoms can include rapid breathing, swelling, blood in feces and just generalized weakness.
According to an entry in the Merck Veterinary Manual by Peter J. Timoney, MVP, PhD, University of Kentucky, the disease is widespread and found through the world. The article clearly states that, "All equids infected with EIA virus remain lifelong carriers." Thus there is no cure.
EIA is a blood-borne infection but Timoney cautions that all body fluids of affected individuals along with tissues should be regarded as potentially infectious. He states that even nasal swabs have shown signs of the infection. EIA can also be passed to foals in utero.
So, how exactly is EIA passed from an infected individual. Biting insects to start with. The fly just acts as a transporter as the actual insect is not infected. The blood retained on the mouth of the insect after feeding on an infected animal is then transferred to its next victim and the infection occurs. Horse flies, deer flies and even stable flies have been proven to be the most "efficient vectors" of the virus.
The rate of infection and spread is influenced by the number of flies, density of horses and certainly the level of infection within the infected animal. During hot and humid times where flies are in high numbers, the risk of infection is much higher.
The disease can also be spread iatrogenically through the re-use of blood-contaminated syringes and needles, surgical instruments, dental equipment and IV sets. According to Timoney, the virus can live up to 96 hours on a contaminated needle. He very specifically states, "The importance of iatrogenic spread of EIA cannot be overstated."
There is no known treatment available for EIA. No cure. No antiviral treatment. The most common and sometimes even requirement is euthanasia. The only alternative to this harsh solution is permanent isolation and quarantine of the infected animal. This means that the horse would need to be kept at a distance of at least 200 yards from all other equine individuals for the rest of its natural life.
Annual testing should occur by horse owners. In the case of an outbreak, more frequent testing is obviously recommended. All horses introduced to a new herd should have a negative Coggins test before introduced and if not available, the horse should be quarantined until the test is received. Routine application of insecticides and/or repellants should also be used to control the fly population around horses.
Good hygiene is a must to control the spread of this lethal disease. The awareness of the dangers of contaminated needles, syringes, along with surgical or dental equipment cannot be stressed enough. Strict principles of bio-security measures should always be observed. Prevention is really key here.
According to the article in the Merck Manual, here are the specific measures listed to prevent and/or control the spread of the disease:
- Infected horses become lifelong carriers and pose a risk of infection to other horses. Management options for an EIA-positive horse are euthanasia or lifetime quarantine, with permanent isolation at least 200 yards away from noninfected horses.
- Prevention is key to stopping the spread of EIA.
- Use a sterile needle, syringe, and IV set for all injections or treatments.
- Disinfect dental, tattoo, surgical equipment, lip chains, and bits thoroughly between horses. Remove all debris and blood with soap and water before disinfection.
- Only administer commercially licensed blood or blood products.
- Keep open wounds clean and covered, if possible.
- Use a sterile needle and syringe each time when puncturing a multidose medication bottle.
- Use sterile technique when drawing up and administering medications.
- Require proof of a recent negative EIA test upon introduction of a horse onto a premises for the first time.
- Practice good fly control by regular mucking out of stalls, proper disposal of manure away from horse stabling areas, and using fly sprays or natural predators to minimize fly presence.
Unfortunately, the equine community is being faced with an outbreak and needs to be vigilant about taking care of their precious equine partners. It's time to take note, get educated, and certainly get the horses tested. Your knowledgeable veterinarian can advise you on the best practices and help you navigate bio-security.
As a side note, there has been no evidence ever presented that EIA is transmissible to humans.
With all of the information available it is important to note the seriousness of the current outbreak. A search on the Equine Disease Communication Center website will provide the most current reports of infection.
Photo by Christine Mendoza on Unsplash