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  Discussion on EPM Vaccine Questions
Author Message
Member:
Count

Posted on Monday, May 19, 2003 - 12:14 pm:

Dear Dr. O,
What is your latest information on the EPM vaccine? We live in La. possums, armadillos, birds, etc everwhere. Our vet initially did not recommend it (last yr); now, she says she's going to give it to her horses. Another vet we know is very much against it.
Have read your info on vaccine and EPM.
Thanks in advance,
Ann
Moderator:
DrO

Posted on Tuesday, May 20, 2003 - 7:37 am:

Hello Chris,
There is a real black hole on information on this vaccine. I have heard nothing in over a year.
DrO
Member:
Cmitch

Posted on Monday, Feb 21, 2005 - 8:52 pm:

I tried to post this yesterday, must not have went through. Anything new on the EPM vaccine for 2005? Heard they recommended it at a major vet conference this year. My vet wants to give my guys it this year.....just not sure.
Moderator:
DrO

Posted on Thursday, Feb 24, 2005 - 7:07 am:

Cindy there was this report last spring and this is still the status quo:
Vet Ther. 2004 Spring;5(1):34-42.
Evaluation of immune responses in horses immunized using a killed Sarcocystis neurona vaccine.

Marsh AE, Lakritz J, Johnson PJ, Miller MA, Chiang YW, Chu HJ.

Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA.

Clinically normal horses developed cellular immunity to Sarcocystis neurona following IM vaccination with a commercial killed S. neurona vaccine, as indicated by the development of measurable anti-S. neurona IgG antibodies and additional intradermal skin testing. Large-scale independent assessments of the vaccine's performance and safety are in progress under field conditions. The next step in the evaluation of this vaccine would be to attempt experimental challenge after a reproducible reliable equine model of S. neurona encephalitis has been established that allows for reisolation of the pathogen after challenge.

As stated in the report there has been progress on finding a disease model that results in dependable infection so that the vaccine can be tested. This has been one of the problems in the past: you could not reliably cause disease in horses by simply exposing them to the organism. This made evaluation of the vaccine difficult as simple measuremnts of immune response do not correlate well with disease protection.
DrO
Member:
Rob10549

Posted on Tuesday, May 10, 2005 - 2:32 pm:

Of interest; Fort Dodge is extremely helpful and will connect you to a veterinarian who is in charge of the vaccine's efficacy. My horse was given the EPM vaccine two years in a row but never followed up with a booster! Without the booster the shot is worthless. I was never even asked if I wanted my horse to receive the vaccine as the veterinary practice never notified horse owners and just went ahead and gave them the vaccine. My horse and the horse that lived next to him both came down with EPM within the two year span following the vaccinations...without the boosters. I just recently found this out when I went to change barns and someone noticed that on my bill my horse had received the vaccine. I thought they were crazy! The moral of the story; make sure that if you opt for this unapproved drug that you make sure your horse gets the booster. I now have a veterinarian at Fort Dodge who I must contact monthly to update her on my horse's condition. He suffered a rear suspensory ligament injury a month before being diagnosed with the EPM. The injury may have been a result of him favoring the good leg as the other rear leg is now neurologically deficient. Know what your horse is receiving when the vet comes to vaccinate! They do not know if the vaccine, despite that it is a dead vaccine, can actually cause the disease.
New Member:
jessebel

Posted on Tuesday, May 1, 2007 - 1:09 pm:

It is 2007, any progress on the EPM vaccine? My vet recommends the vaccine and says he has used it for over 2 years. He is treating one of my horses for EPM now but I have 2 others I'd like to protect from this disease.
Member:
ryle

Posted on Tuesday, May 1, 2007 - 7:43 pm:

Ft. Dodge has still not been able to get full licensure because they haven't proven effectiveness of the vaccine.

With the fact that the vaccine isn't PROVEN effective and that it fouls up the diagnostic testing, I would not opt to give it to my own horses....and I live in heavy opossum territory.

Robin, there is little risk of the killed protozoa causing disease as it's their reproduction within the cells of the central nervous system that causes the disease.
New Member:
lucyc1

Posted on Friday, Feb 20, 2009 - 7:40 pm:

Is it true that the EPM vaccine has been withdrawn? If it is still available is there any more information?

Dr. O made a comment earlier in this thread that caught my attention. He said that "horses may have preexisting CNS infection that does not cause disease but once vaccinated the sensitized immune system causes inflammation which interferes with normal CNS function." This seems logical and worrisome. Is there any more info on this, or on the effectiveness of the vaccine? Is it still available?
Moderator:
DrO

Posted on Saturday, Feb 21, 2009 - 9:13 am:

I have not heard an announcement Lucy, but I see where it has been removed from a Fort Dodge list of vaccines available. It was there recently as it is still in the google link description.

As to availability you still find it listed at some wholesalers but that is no guarantee. I can find no further research for or against the activity of this vaccine than what is in the article.
DrO
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