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  Discussion on New Vaccine Recommendations for Preventing EHV-1 Infection
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Moderator:
DrO

Posted on Thursday, Jun 2, 2005 - 11:04 am:

From Cornell News Service comes this bit of information that shows superior protection from using the commercially available modified live virus vaccine vs the killed vaccine at least to the respiratory disease. Note that the size of the study small and the difference probably not significant with respect to the neurological disease but it is exciting and suggests that larger studies will find a significant difference:

May 26, 2005
After deadly outbreak of horse herpes at Churchill Downs, Cornell researcher announces early finding of effective prevention
By Krishna Ramanujan

ITHACA, N.Y. -- Following the recent deadly outbreak of equine herpes virus at Churchill Downs, home of the Kentucky Derby, a Cornell University virologist says his preliminary research indicates that vaccines containing weakened live viruses, called modified live vaccines (MLV), appear to be more effective in preventing horse herpes than other more widely used vaccines.

"It's important that people know that the MLV has been in use for decades, has proven to be reasonably safe, and in -- my opinion -- it should be the vaccine of choice, at least in non-pregnant animals," said Klaus Osterrieder, associate professor of virology in the College of Veterinary Medicine at Cornell. The college is home to the Animal Health Diagnostic Center, the official regulatory diagnostic laboratory for equine diseases in New York state.

On May 18, two horses stabled at Churchill Downs showed symptoms of the neurological form of equine herpes and were euthanized, leading to concern at the May 22 Preakness Stakes at Pimlico Race Course near Baltimore. In anticipation of the June 11, $1 million Belmont Stakes, the third leg of the Triple Crown, in Belmont, N.Y., the New York Racing Association (NYRA) on May 18 issued travel restrictions for all horses that might have been exposed to equine herpes virus, with special attention paid to those stabled at Churchill Downs since May 1.

In some 90 percent of infected horses, equine herpes virus type 1 (EHV-1) leads to a mild upper respiratory infection with fever, nasal discharge and fatigue for a day or two. The virus can also cause pregnant mares to abort, and in its severest form it can lead to neurological disorders, loss of coordination and even death. The virus is spread mainly by intimate contact between horses. Once infected, a horse carries the virus for the rest of its life in a "latent" (dormant) state. The same symptoms from the initial infection can be reactivated by stress later in life.

Osterrieder will present his new findings on vaccine effectiveness, involving a limited study of 15 horses, at a luncheon meeting with other veterinarians and specialists at the annual American College of Veterinary Internal Medicine Forum, June 2, in Baltimore. The luncheon will be paid for by Pfizer Inc., which provided Osterrieder with a $50,000 unrestricted grant to conduct research of his choosing. Pfizer is the only company that makes MLVs for equine herpes virus.

Osterrieder's preliminary study compared the effectiveness of MLV vaccines to another more widely used vaccine for equine herpes. Owners and veterinarians have been wary of live vaccines because of past incidences in which a previous MLV that was incompletely weakened caused neurological disease symptoms after it was administered. The more widely used type of vaccine, called an inactivated vaccine, employs a killed virus to activate the horse's immune response.

Osterrieder vaccinated five horses with an MLV and five with an inactivated virus; five received no vaccination. None of the 15 horses was pregnant. The horses were then exposed to the herpes virus.

The study found that the horses with MLV vaccinations consistently had lower fevers, no neurological disorders and less virus in nasal fluids. One horse vaccinated with the inactivated virus and one from the control group showed mild neurological symptoms. All the horses, however, have fully recovered.

For more see the article above.
DrO
Moderator:
DrO

Posted on Thursday, Jun 2, 2005 - 11:52 am:

As an addendum and correction to the above post on MLV EHV-1 vaccine after studying the recommendations on vaccination 2 things fall out:
1) The MLV vaccine now has approval for pregnant mares but I think the recommended schedule has a misprint on the Pfizer site that I need to pursue.
2) Because it does not have EHV4 in combination a complicated vaccine schedule arrises for the incorporation into a show horses schedule.
I will work on this the next several weeks to see if we cannot create a practical schedule and post it to the Vaccine Schedule article.

DrO
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