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Discussion on EPM suppresses immunity to EPM in those with the disease
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Moderator:
DrO
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Posted on Wednesday, Jul 20, 2005 - 9:16 am:
We know that in areas where the organism that causes EPM, Sarcocystis neurona, is prevalent more than half the healthy horses have positive titers that indicate exposure. So why do only a very small percentage develop clinical disease?
Increasingly it appears that the organism is able to impair the immune system of some individuals allowing the organism to prosper. The following work provides further support for this idea. A practical immediate use of this work is that while blood work showing exposure is not that helpful perhaps the combination of clinical signs, a positive EPM titer (blood work), and a suppressed immune system toward EPM would be diagnostically significant? Now someone needs to test this and develop a commercial test. You would think as much money as is spent on this disease this would be profitable, see the article for more on EPM.
Clin Diagn Lab Immunol. 2005 May;12(5):644-6.
Cytokine gene expression in response to SnSAG1 in horses with equine protozoal myeloencephalitis.
Spencer JA, Deinnocentes P, Moyana EM, Guarino AJ, Ellison SE, Bird RC, Blagburn BL.
Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA.
Equine protozoal myeloencephalitis (EPM) is a neurologic synDrOme seen in horses from the Americas and is mainly caused by Sarcocystis neurona. Recently, a 29-kDa surface antigen from S. neurona merozoites was identified as being highly immunodominant on a Western blot. This antigen has been sequenced and cloned, and the expressed protein has been named SnSAG1. In a previous study, cell-mediated immune responses to SnSAG1 were shown to be statistically significantly reduced in horses with EPM in comparison to EPM-negative control horses. It therefore appears as though the parasite is able to induce immunosuppression towards parasite-derived antigens as parasite-specific responses are decreased. Isolated peripheral blood lymphocytes from 21 EPM (cerebrospinal fluid [CSF] Western blot)-negative horses with no clinical signs and 21 horses with clinical signs of EPM (CSF Western blot positive) were cocultured with SnSAG1 for 48 and 72 h, and the effect on cytokine production was investigated by means of reverse transcriptase PCR. Cytokines assayed include gamma interferon (IFN-gamma), tumor necrosis factor alpha, interleukin (IL)-2, IL-4, and IL-6. beta-Actin was used as the housekeeping gene. A Wilcoxon signed-rank test of the findings indicated that there was a statistically significant decrease in IFN-gamma production after 48 h in culture for samples from horses with clinical disease. There was also a statistically significant increase in IL-4 production after 72 h in culture for samples from horses with EPM. These results further support the notion that this parasite is able to subvert the immune system in horses with clinical disease.
DrO
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Member:
Shark
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Posted on Tuesday, Jul 26, 2005 - 8:11 pm:
Hello Doctor O.
I purchased a Appendix quarter horse gelding age 18 years, last Jan 1 2004.He stood at 16 hands and weighed in at 900 lb. and drug his left rear hoof.I was told the reason he drug his left rear hoof is because,( on his bad days his arthritis flares up).
I thought he was just starved and needed a helping hand so I paid a 100.00 for him a sprung him out of the nasty barn I found him in. In March of 04 he was diagnosed with E.P.M.
He was started with the old style triple sulfate medications. His supplements at that time were Vitamin E and selenium, wight builder, perception strength corta-flex..
In the mornings I would give his medication orally while he had a empty tummy. then hand walk him for an hour or two.This system seem to work until August 04 when he relapsed and stated losing his balance again..
He was then put on the Marque for two months.( I nearly robbed a bank to pay for these new drugs)
Today the E.P.M. is gone..He now stands at 16.1 hands and weighs in at 1250 lbs. He's been put on senior feed (Triple Crown) and gets two flakes in the morning and two flakes in the evening..and allowed to graze from 8 in the morning till 6 in the evening along side his buddies..his supplements now are Regular Corta-Flex, Muscle-Up Powder by (Animed), a biotin supplement for his hooves..
The Vet OKed exercise so hes ridden by a light rider (90 lb) twice a week for an hour an half then I take a lesson with a qualified English instructor for about 2 hours once a week. (err I are Western he were trained English )
Oh yes and the dragging rear foot, x rays indicated a very light case of navicular which has been treated with corrective shoeing, I have the farrier come out and do his feet every 4 weeks, this seems to have solved his dragging tootsie problem.
Thats his history.. now for my questions
1.what other wormer's besides Safeguard can I use on Ben that will not make him Ill again.(I was told by vet the stronger wormer's like Quest will make him sick again)
2.what are your thoughts on the new E.P.M. inoculation? Since he already had E.P.M should I worry about having this shot given along with the rest of his shots? Hasn't he built up an immunity to the E.P.M. ?
3.Iron Horse* Finish Line B-complex supplement to build up his red blood cell, it seems to me that by giving this booster it would help with his immune system..( I was told not to give it to him because it will make him Hot) What is your opinion on this Dr. O ?
4. whats the main differnce between corn oil and vegatable oil and should I be giving this stuff to Ben during the summer months?
Thanks for any info Dr. O
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Member:
Ryle
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Posted on Tuesday, Jul 26, 2005 - 10:37 pm:
Lesslie,
As long as Ben is healthy now, you can use any of the approved dewormers on him. Some horses have had a worsen of neurological symptoms if given Ivermectin while they have EPM, but once the disease is treated and the neurological symptoms have disappeared many owners go back to using Ivermectin with no problem.
The vaccine has not been proven safe of effective, so you may just be wasting your money if you give it. Besides, horses can get exposed and have antibodies to the protozoa that causes EPM for years without ever contracting EPM. It makes me wonder why a vaccine would really be effective since the antibodies can be present from actual natural exposure and horses can still contract the disease. Since it appears that whether or not a horse is able to rid itself of the protozoa has to do with stresses that can hamper immune system function, I would worry more about limiting exposure as much as possible and trying to keep from overworking/overstressing your horse rather then giving a vaccine that may do no good.
RBC's are not a part of the immune system and this supplement is not designed to "boost the immune system". The main things for maintaining good immune function is to give your horse a good balanced diet and appropriate exercise. There are many supplements on the market designed specifically for the immune system, but if you give an appropriate diet his body has what it needs to keep his immune system functioning.
Anyway, I know I'm not Dr. O, but I thought I would throw out my opinions and experiences.
BTW, if you would like to talk to other owners of EPM horses, there is an EPM support group on yahoo.
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Member:
Shark
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Posted on Wednesday, Jul 27, 2005 - 12:49 pm:
Thanks for the info Cynthia.
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