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Discussion on WNV vaccine
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Member:
Debh
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Posted on Monday, Feb 24, 2003 - 4:58 pm:
Hi all
I have a question for Dr. O.
The idea of preexposure vaccination in the face of a outbreak makes sense to me. I think it would help their immune systems to prepair for a new challenge hopefully reducing the number of horses which develop the serious form of the desease.
But, then down the road once the virus becomes endemic to the area and (for the sake of argument I'll suggest that no mosquito control program will be 100% effective) the animals are continuously exposed all through mosquito season.
Would this exposure build up a natural immunity that would "top up" that stimulated by the vaccine?
I've always been told that natural immunity is generally considered more effective and longer lasting than that which is manufactured(vaccine). (Of course all one has to do is survive the initial exposure  )
Anyway, my question is, would it be appropriate to vaccinate a immunologically nieve population to help them get over the hump of a potential outbreak and then discontinue vaccination after ? year(s) once the virus becomes endemic and the local population of animals are no longer immunologically nieve?
Thanks as always,
D.
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Moderator:
DrO
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Posted on Tuesday, Feb 25, 2003 - 7:18 am:
A wonderful question whose answer unfortunately is unknown. It would depend on a lot of information that we do not have at this time and some variables that change from locale to locale. The most important questions/variables would be:
1) Vaccine efficacy: a very good vaccine may prevent natural immunity from occuring by stemming the infection before a system wide response is generated.
2) Degree of immunity conferred by infection.
3) Freqency of exposure: if the natural exposure frequency is less than that required to maintain immunity obviously this is not an option.
Currently at the levels of infection we are seeing natural exposure may be too infrequent and I do not know of any reports on how long natural immunity lasts.
DrO
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Member:
Debh
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Posted on Tuesday, Feb 25, 2003 - 1:33 pm:
Hi Dr. O
Do you know if any long term studies are in the works? I'm guessing that checking titers over the long term would answer my question.
Thanks
D.
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Moderator:
DrO
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Posted on Wednesday, Feb 26, 2003 - 12:09 am:
No studies I know of. You could even monitor for natural exposure vs vaccine titer testing for both IgM and IgG levels (see WNV article for more on this) but don't expect to save cash doing this.
DrO
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Member:
Debh
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Posted on Wednesday, Feb 26, 2003 - 4:35 pm:
Hi Dr. O
No kidding. It was not so much the $$ that I was worried about (other than I wish I owned stock in Wyeth just now ;0).
I just wonder at times about the practice of pumping such a smorg of vaccines into the ponies every year. It seems to be a practice that is not approved of in human medicine even some small animal practioners I know are leaning away from the practice of vaccinating yearly.
Yet...
Yet, the studies I've seen on this vaccine look good; low reactions, good efficacy and all that.
Very nasty looking desease.
No good reasons not to use the vaccine.
Still I wonder.
Thanks as always
D.
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Moderator:
DrO
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Posted on Wednesday, Feb 26, 2003 - 6:20 pm:
There is a lot of things we do for our horses / pets that when you stop and think about....for instance....we prepurchase exam our horses but what about our spouses?
I agree it seems horse folks want to take zero risk and in my opinion end up taking greater risks. I remember the big PHF scare where I spent 3 years almost pleading with my clients to not use this poor quality vaccine for a disease we did not have locally. Not all of my veterinary collegues were helpful with this either. It is a hard problem to evaluate once vaccination is begun cause then you no longer know the incidence rate of the diseases in the population of horses you care for.
DrO
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Member:
Dres
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Posted on Wednesday, Feb 26, 2003 - 6:57 pm:
<there>
 sorry i had to laugh at that one... and what about a guarantee for that husband...??
Ann
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Member:
Debh
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Posted on Thursday, Feb 27, 2003 - 1:19 pm:
D.
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Member:
Hwood
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Posted on Friday, Mar 28, 2003 - 10:12 pm:
From the 9news.com site, Denver, CO.
CSU study says West Nile vaccine increases horse’s survival created: March 28, 2003 - 5:47 PM
updated: March 28, 2003 - 7:48 PM
Written By: Web Producer Jeannie Piper
FORT COLLINS - A new study at Colorado State University says vaccinations can help protect horses from West Nile disease.
Researchers contacted more than 500 owners of infected animals in Colorado and Nebraska and found that nearly one-third of the sick horses died. But horses that received at least one dose of vaccine were a lot more likely to survive.
Horses will need booster shots every year as long as West Nile remains a threat. Owners can also spray their horses with repellent and get rid of breeding places for mosquitoes.
Thirteen people got sick with West Nile disease in Colorado last year. None of them died, but there have been fatalities in other states.
(Copyright 2003 by 9NEWS KUSA-TV, All Rights Reserved)
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Member:
Mfanaras
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Posted on Tuesday, Jun 10, 2003 - 6:18 am:
When should foal be vaccinated with West Nile vaccine? The foal was born Feb. 28 2003 and the mare was vaccinated April 8 and May 14 2003.
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Member:
Mfinan
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Posted on Tuesday, Jun 10, 2003 - 12:04 pm:
My vet has suggested vaccination for foals be at 3 months. All my other horses receive their boosters every 6 months including one that had WNV last fall. My little guy will receive his in July.
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Member:
Jerre
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Posted on Tuesday, Jun 10, 2003 - 1:56 pm:
Hi, I'm in western Washington state. My vet suggests WNV at 2, 3 and 4 months for the foal. The mare was up to date and boosted just a week before the baby was born (we didn't know she was in foal, but that's another story!)
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Moderator:
DrO
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Posted on Tuesday, Jun 10, 2003 - 9:28 pm:
Currently it is recommended that the schedule for foals of vaccinated mares be different than non-vaccinated mares. Also risk figures into the current best recommendation. You will find the best current information at » Equine Diseases » Nervous System » West Nile Virus. This information is updated as new information comes in.
DrO
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Member:
Tagloili
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Posted on Tuesday, Jun 10, 2003 - 10:40 pm:
My vet administered WNV to our two month old QH filly today. Mosquitos are really getting bad in Aurora, Colorado because of the moisture we've been getting. In addition, I purchased a Liberty Mosquito Magnet today and it is up and running.
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Moderator:
DrO
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Posted on Wednesday, Jun 11, 2003 - 6:04 am:
George we have an article up on reducing mosquitoes see, » Equine Diseases » Skin Diseases » Mosquito Control Around Horses and Barns.
DrO
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