Can Humans Get Equine Infectious Anemia?

Last Updated on December 26, 2022

We all want to keep our horses in perfect health and that often involves a lot of hands-on, close-contact work. Rabies and ringworm are two diseases that might be on your radar, but have you ever wondered what other diseases you could get from your partner like equine infectious anemia? and do you know if can humans get equine infectious anemia?

What is Equine Infectious Anemia?

Equine Infectious Anemia (EIA), aka Swamp Fever, is a disease you may have heard your veterinarian mention during routine shots, or maybe you once took a close look at your Coggins Test paperwork.  

It’s a viral disease of horses that is generally transmitted by biting flies – like horseflies. It is a lentivirus, like the human immunodeficiency virus (HIV), and is so dangerous that any equine that tests positive has to be quarantined 200 yards away from any other horse.

Pretty scary, right? Equine Infectious Anemia is a major disease of horses and ponies but is rarer in mules and even rarer in donkeys. (Spoiler alert: it has to do with genetics.)

It is such a major disease that it was first described in 1843 and was one of the very first lentiviruses to be discovered! On top of that, it was the first animal disease that was determined to have been caused by a virus back in 1904. The virus was finally isolated in the late 1960s.

How Does Equine Infectious Anemia Spread?

Luckily for us, this virus doesn’t survive long outside of a horse! When a fly bites an infected horse, the virus hitches a ride on the fly’s mouthparts to its next victim. If the fly doesn’t find one within four hours, the virus dies. Humans can also accidentally transmit it through contaminated syringes, so it’s good practice to never reuse a needle!

How Does Equine Infectious Anemia Spread

What Are the Signs My Horse has EIA?

There are three different stages: acute, chronic, and unapparent.

During the acute stage horses will suddenly become sick, have a high fever, anemia, weakness, swelling of the lower parts of the body, a weak pulse, irregular heartbeat, and possibly even sudden death.

In chronic cases, the symptoms are recurrent fever, depression, weight loss, anemia, and swelling of the lower part of the body.  

Finally, horses with unapparent EIA show no outward signs of the disease.

How Can I Prevent EIA?

There is no vaccine, so the only way to prevent EIA is to keep your horse away from carriers (horse flies, deer flies, or other infected horses). A routine Coggins Test makes sure that no EIA-positive horses cross state borders or attend shows. 

Even if your horse isn’t sick it’s still wise to test them before moving them from one barn to another. Veterinarians have noted that most horses with the disease appear healthy, but they can still pass the disease to other horses.

How can I prevent EIA

Read more about how to keep flies away from your horse: choosing the Best Fly Boots or making a Homemade Fly Spray.

So Can Humans Get Equine Infectious Anemia?

Why Can’t Humans get EIA?

It turns out that lentiviruses are very specific to the species it infects. These viruses need a special receptor that is only found on equine cells and therefore cannot infect human cells.

While inside of the cell, the virus then requires the host’s genetic code to replicate. That’s why it’s so much rarer in mules and donkeys and is also why we can’t get it.

Since no humans have ever contracted EIA, they have started using it instead of HIV for gene therapy.

I hope this article helped you learn more about equine infectious anemia. If so, please share this article.


Is there a treatment for equine infectious anemia (EIA)?

So far there is no cure or vaccine for EIA. Because infected animals carry the virus till the end of their lives and present a great risk of infection for other equines, they must be either permanently isolated or euthanized. Supportive therapy can relieve some clinical signs in individual horses, but the most important thing you can do to help prevent your horse from getting sick is to keep your horse away from other infected horses. 

How is equine infectious anemia spread?

EIA is a viral disease that can cause severe damage to your horse’s immune system. It is spread through direct contact with blood, semen, vaginal secretions, urine, saliva, nasal discharge or other body fluids of infected horses. 
Undeniably, the primary way EIA spreads is through direct or indirect contact with an infected animal. This includes riding or working directly with an infected horse, handling feed or water buckets that have been touched by an infected horse, being bitten by an insect that has fed on an infected horse, or even just being in the same area as an infected horse. EIA is also one of those diseases that is very difficult if not impossible to eradicate once it has taken hold in a population because of the carrier state of the virus. That means even after all infected animals are identified and removed from the herd, there will still be some animals that carry the virus but are asymptomatic and can unknowingly transmit the disease to other animals.

What are the symptoms of EIA?

What is the earliest sign your horse might be infected with equine infectious anemia? The first indication your horse has EIA is fever. This is followed closely by decreased appetite or weight loss. After about a week, your horse may start having muscle pain. He might become listless and have trouble getting up or moving. Later in the disease, your horse will develop a swollen abdomen caused by fluid accumulation in the abdominal cavity. He will also develop a weak pulse and breathing rate.

Why is equine infectious anemia called swamp fever?

"Swamp fever" is a generic term for any infection that typically occurs in humid environment like swamps and is transmitted by mosquitoes or other blood sucking insects that thrive in humid environment. Two very common examples are Malaria and Leptospirosis. Equine infectious anemia also falls in this category. It is caused by a retrovirus, similar to HIV in humans, which is transmitted by bloodsucking insects, like horse flies, deer flies and stable flies. In addition to horses, it can be found in zebras, ponies, donkeys and mules. 

What is an EIA test for horses?

The first step in determining if your horse has EIA is a blood test called the “Coggins Test.” This test looks for the presence of antibodies to the EIA virus in your horse’s blood. If your horse has the disease, his body will produce these antibodies as part of its immune response. A negative Coggins test does not guarantee your horse is free of the disease, but it does mean he is not currently infected. Of course, the only way to know for sure is with a biopsy of his bone marrow, spleen or lymph nodes. This is an extremely painful procedure that requires anesthesia. It is done by a veterinarian or an equine surgeon. The results are usually available in seven to ten days.