I recently bought a mare from the racetrack (actually 3). To be allowed to import horses in to Maputo we need to do an Eva test, and she tested +. Everyone assured me it was impossible as Eva does not excist in SA. 2nd test sent and same the result so they decided to send the blood to a dif lab- which came back neg. A 4th test was taken and sent to the 1st lab (which had previously tested +) but they used a dif method to process the blood and once again she came back +. This mare has been with the same owner since bought as a yearling, lived on the racetrack and NEVER been in contact with a stallion or near a horse that has eva EVERYONE involved tells me. Previous owner even wrote a letter guaranteeing this. Now, the state vet is checking possibility of sending blood to Europe (lookign for funding as very expensive) but it will be sent in the beg of next year. Now, my question is, IF she is +, will she always be a carrier or does it eventually clear? Can she be at some stage brought to me without risking my other horses/stallions/pregnant mares to get it?
Apart form being utterly concerned about my own horse, I can only imagine, that IF this test is correct, what it will do to the horse world in Sa as SA does not have Eva.
As I presume that you have had this mare tested over a period of at least 3 weeks, this is absolutely and categorically not an issue!!!
Let's look a little more at EVA to understand why and also to understand how your mare may have been exposed to the virus:
EVA is primarily a respiratory disease. As your mare has never been bred she therefore probably was exposed through the respiratory route;
EVA can be asymptomatic (show no symptoms) when in the acute ("active") stages of the disease - so there is no way that the previous owner could know for sure that she had never been exposed;
EAV (the disease is EVA, the virus is the EAV) is transferred in bodily fluids from acutely sick animals, so mucus transfer is possible. This means that a horse stood next to an asymptomatically sick horse can be infected by that mode of transfer;
OK - here's the big one: EAV is a testosterone-dependent virus for bodily maintenance. In other words, in order to be perpetually infectious, the horse has to have testosterone present - i.e. be a stallion. Neither mares nor geldings can harbour the virus and are only infectious during the acute stages of the disease - which lasts about 3 weeks.
Right. Now we've gone over those important key points, let's look at some of the individual points in your post, as you are very misinformed!
To be allowed to import horses in to Maputo we need to do an Eva test, and she tested +.
What your mare actually tested positive for is antibodies to the virus, not viral presence itself (I am presuming that the mare was not in the active stages - "acute" - of the disease, which would have required her to have been exposed in the preceding 3 weeks, which from what you say is unlikely). In other words, at some point in the past she has either been exposed to an animal that has been infectious and has had the disease herself, or she has been vaccinated. There is no way to differentiate between an animal that has been vaccinated or one that has been exposed to the disease. Both animals will develop antibodies to the virus. In either event, as long as the mare is not within 3 weeks of having been exposed to an active case of the disease it does not matter as she cannot be infectious. Actually, in a way, it's a good thing, as your mare cannot currently (as long as titre levels remain elevated) become infected with EVA if she does come into contact with an infectious animal!
Everyone assured me it was impossible as Eva does not excist in SA.
There was an outbreak of EVA in South Africa several years ago. It was closely tracked at the time and almost certainly any stallion exposed was tested and either found to be negative for the virus (see more later on that phrase), or removed from the population. Young horses under the age of 9 months that may have been exposed were possibly not tested as they would either have been still with their dam (who would have been tested) or were deemed "no risk" as the colts would not have been mature, and therefore have no testosterone, and not be capable of harbouring the virus on a permanent basis. Any animal exposed during that time would be likely to have become infected - which may not have been noticed as it can be asymptomatic - and therefore developed the antibodies which could still be present today.
Previous owner even wrote a letter guaranteeing this.
As I noted and for the reasons given, this - although kind of them - actually is worthless as it can't be guaranteed.
Now, the state vet is checking possibility of sending blood to Europe (lookign for funding as very expensive) but it will be sent in the beg of next year.
While the State Vet may be concerned about attempting to identify the traceback (i.e. where it came from), other than that, this is overkill and you most decidedly should not be held financially responsible for further testing! Again... as long as the mare has tested with the stable or declining titre levels for at least 3 weeks, it doesn't matter that she has antibody presence as she cannot be infectious. Note the "stable or declining" levels as well as the 3 week testing duration. Think of this as a bit like a common cold in humans (it's not identical, but you'll see where I'm going with this...). When you catch a cold, while you have the active stages of the cold present - coughing, sneezing, sore throat etc. - you are infectious. That infectious state may continue for a few days after the coughing and sneezing continues, but then you're no longer infectious. If you happen to have given that cold to someone else in your family, they will also be infectious while they are coughing and sneezing - but even if they cough and sneeze on you, you will not catch the cold "back" because you - having already had it - have developed antibodies to the cold. You're no longer infectious, but you still carry the antibodies. The same applies with the mare that is exposed to EVA. Note that unlike a cold though, EVA doesn't have to show symptoms.
IF she is +, will she always be a carrier or does it eventually clear?
Titre levels will drop over time - but (yet again! ) - other than for the first three weeks after exposure to the disease, elevated titre (antibody) levels don't matter in the mare as she cannot perpetually remain infectious.
Can she be at some stage brought to me without risking my other horses/stallions/pregnant mares to get it?
I'm hoping by now, you're getting the message... As long as she is not within the 3 week period after initial exposure to an active case of the disease, there is no risk of furthering infection from a mare.
I can only imagine, that IF this test is correct, what it will do to the horse world in Sa as SA does not have Eva.
The biggest question is where was the initial point of contact and that is what the officials should be looking for. Make sure that any official that you deal with is absolutely and completely clear on the fact that a mare - other than for the 3 weeks or so after initial exposure to an active case - is not and can not be infectious. Mares do not harbour the disease like stallions do. The risk period for your mare if your testing period has gone on for more than 3 weeks has passed. Even had she just been exposed the day before the first test (which is unlikely but not impossible) she would no longer be infectious. If they are attempting to impose any sort of quarantine, then - with the 3 week period in mind - it is unnecessary. Nor should you have any concerns about exposing your own animals as long as it is at least 3 weeks since the first "positive" test.
To clarify my point above about a stallion being "tested negative for the virus": Stallions that have been exposed to an active case of the disease may (not all do) become perpetual harbourers of the virus in their secondary sex glands and secrete (often called "shedding") the virus in their ejaculates when bred or collected. This can then infect the mare that is being bred. The protocol for testing stallions is therefore to initially do a blood test. If this comes back positive (like it has for your mare), this actually shows presence of EAV antibodies, not viral presence. The next step with a stallion who shows antibody presence is to collect semen and determine if there is viral presence in the semen. If there is viral presence, the horse has been identified as a "shedder" stallion and should not be bred to unvaccinated (i.e. mares that do not have an elevated antibody titre level) mare. Except while in the acute stages of the disease a "shedder" stallion will not be infectious other than through the seminal/urinary tract route. In other words, nose-to-nose contact with a shedder stallion will not result in transmission of the virus. "Shedder stallions" are considered "chronically infected" with EAV - in other words, it is a long-term issue as opposed to the "acute" form, which is the "immediate and short-term" condition such as is seen in the first three weeks of infection.
We have several detailed articles in our articles section about EVA - scroll to the foot of the page and they are to be found in the "General Articles" section. One of those is written with probably the world-leader in EVA research, Dr. Peter Timoney, and can be considered a definitive article on the subject. You might want to print it off and "arm" yourself with it!
Hopefully this has helped. If you have more questions, please do not hesitate to ask them - you can either do it here on this thread, or contact us for a private response if you prefer. we would also be interested to be kept apprised of what transpires (again, you might want to do that privately).
I was honestly in real concern of what to do. Horse tested + 3 out of 4 times, and as I had explained a threat to transmit to ALL my other horses. The fact that no one knows of any cases in Sa made everything more of a concern, as where would she have gotten it? I had just decided to leave her behind in Sa and bring my other 2 mares to Maputo, while they would send blood to Europe to find out more about her eva- which I now decided not to- she can finally, after months of worrying-trying to find info online- be brought to me! (not to talk about the fortune I've had to pay for sabling, re-doing tests etc etc, all to find out it was no point to it all). I have learnt SO much!
I would guess that the next question is: can she be put in foal without any risk to the stallion or herlsef or the foal?
can she be put in foal without any risk to the stallion or herlsef or the foal?
Yes. She is not infectious. She merely has antibody presence, the same as if she had been vaccinated against EVA. In fact you could even breed her to an EAV-shedding stallion and still not have a problem because she has protection from the antibodies.
this is awesome!! Glad you found the site Lisa....Jos is SO very helpful!
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