Equine infectious anemia: what you need to know!
If you are a rancher and use horses or mules as a work tool, or raise these animals for exhibitions and competitions, you can certainly understand the importance of the health of your troops. In that sense, you've probably heard of equine infectious anemia, or EIA, swamp fever, or equine AIDS.
In any case, it is essential to prioritize the health of animals. Therefore, come and learn more about this important disease, the main theme of this content. Follow!
What is and what causes equine infectious anemia?
As the name implies, it is a problem that affects horses, whether horses, mules or donkeys. It has a viral origin and is quite contagious, which increases the need for total care. Unfortunately, this is an incurable disease, which can result in both asymptomatic and symptomatic animals with different stages of clinical signs, which we will detail later on.
Already considered a major obstacle to the growth of equine breeding, equine infectious anemia causes serious losses and economic losses, since the correct conduct is the sacrifice of the sick horse.
Only through laboratory diagnosis is it possible to completely rule out EIA, since asymptomatic animals can continue to spread the virus, even at a distance through insect bites such as horseflies and flies. These insects are important vectors of the disease and represent a great challenge in controlling the endemic disease.
Also known as horse AIDS, this virus receives this title due to its ability to destroy erythrocytes, or red cells, through the individual's own immune system.
In addition, there is the ability to insert the viral DNA into the host's DNA, allowing the formation of the provirus, so that, being incubated, the defense system does not identify it as sick or infected. Thus, it remains for long periods, until the animal is exposed to debilitating diseases or stress, which can trigger the appearance of symptoms.
In other words, the complexity of the host's immune response allows the virus to survive, so it is very difficult to establish a treatment or vaccine that is actually effective.
How the EIA virus is transmitted
You already understood that the level of contagion is extremely high and that controlling the virus is very complicated. Now, how does this widespread propagation happen?
Primarily, the infection can occur through direct contact with the elimination pathways, either through vertical, horizontal, sexual transmission or through vectors. That is:
Elimination routes:
blood;
semen;
urine;
Milk.
Direct transmission:
Vectors – flies and horseflies;
Horizontal – contaminated tools, equipment and materials;
Vertical – intrauterine life, breastfeeding;
Sexual – through contaminated semen.
Bearing in mind that, for contamination to actually occur, it is only necessary to have direct contact with any infected route of elimination, that is, in summary, infected needles and material used for riding with the presence of infected blood can be important foci of EIA.
How then to prevent equine infectious anemia?
Prevention is directly related to basic care, which will definitely cheer you up a little more, as this will depend entirely on your handling care. Therefore, we have selected some good management practices:
Always use disinfected materials – which include: saddles, spurs, halters, needles and any other equipment that may contain traces of infected blood and cause injuries for successive contamination;
Keeping track of flies , or putting in considerable effort;
Be careful with controlled reproductive management ;
Be careful when buying or introducing a new animal into the troop;
Make sure that there are no outbreaks of the disease in the region where you live;
Keep a routine of evaluations with the veterinarian, to monitor the health of the animals;
Special attention to conditions suggestive of the disease – eliminate suspicions ;
Beware of donkeys and mules, as they are relatively resistant to showing clinical signs.
Main symptoms of equine infectious anemia
It is definitely vital to facilitate the identification of the problem; therefore, it is very important to know the main clinical signs of equine infectious anemia.
Obviously, anemia is one of the symptoms caused by the virus, as well as a drop in the amount of platelets, called thrombocytopenia. These are identifiable factors in the acute phase and through laboratory tests. Additionally, you will see:
Acute phase:
acute and persistent fever (1-3 weeks);
jaundice (yellow mucous membranes, such as the lip);
lack of appetite;
bleeding or bleeding (due to lack of platelets);
petechiae (red dots on mucous membranes),
weakness and weight loss;
Performance loss.
Chronic phase:
episodic or persistent fever;
developmental delay;
cachexia (evident and rapid weight loss);
Ventral edema (water belly).
Sub-acute phase (usually occurs for survivors of the acute phase):
moderate and continuous fever;
Unapparent infection.
How can I be sure my pet is sick?
The diagnosis, therefore, is fundamental. It is even a requirement of the animal health bodies in our country, being a modifiable disease, that is, the authorities must be communicated in a positive case.
Laboratory analyzes are performed from collected serum or whole blood, without the addition of anticoagulant. It must be stored under ideal conditions, and forwarded to units accredited by MAPA, accompanied by a review and specific documentation with data on the animal and the property where it is located, as well as the clinical condition observed, which requires the presence of an accredited veterinarian.
The investigation can be direct, through the immunodiffusion test in agar gel - AGID, also known as “Coggins Test ". In this test, there is isolation of the antigen and verification of the presence of antibodies that precipitate or react, modifying the culture medium. However, this result does not detect animals that had contact with the virus in the first 5 to 7 days, around 15 to 25 days are expected for a more faithful result.
To speed up the process, the antibody identification method is the best solution. The ELISA test performs indirect investigation and is much earlier, indicating that the binding antibody is already present around 12 days after infection.
In this context, then, the differential test by means of PCR and/or histopathological observation is also recommended, especially for equine viral arthritis and babesiosis, frequent and very similar in the symptoms presented.
Therefore, in summary, it is advisable to associate the two main tests – IDGA and ELISA, together with the PCR differential and histopathological observation in blood smears.
And now? I already have the diagnosis, what to do?
Unfortunately, there isn't much to do, and not many solutions to come up with. As there is no vaccine or remedy that resolves the issue, the virus, once installed, will remain in the animal forever.
We emphasize the need for compulsory communication of the presence of equine infectious anemia to the competent bodies. Positive equines will be euthanized or isolated, branded with the letter a, requiring serological investigation of all animals, including immediate locations.
Only investigations and the determination of outbreaks of the disease will be suspended in areas that present two negative results from all equines, by analysis of samples from 30 and 60 consecutive days.
In addition, horses that are submitted to exhibitions and competitions, by requirement, must present the certificate of being free of the EIA. Regardless of the end, the test result is valid for 60 days from the collection of samples.
Anyway, here’s everything you need to know about equine infectious anemia. Therefore, it is essential to keep an eye out to avoid contamination as much as possible and to monitor your animals very closely, including with the support of a veterinarian.
After all, equine infectious anemia has no treatment, not even a vaccine, and represents an important compromise in equine breeding.