Be Aware: PreveNile West Nile Virus Vaccine Recalled

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Finally there has been an action to remove West Nile vaccine from the shelf of your veterinarian. Years ago one of my veterinary friends told me that in her experience the vaccine could be even worse than the disease but she had no choice but to vaccinate. It’s my understanding that a lot of horses must have had adverse effects to cause this recall.

You can read a May 4 The article by Stacey Oke, DVM, MSc on the PreveNile West Nile Virus Vaccine Recall by going directly to their site or by clicking

by: Stacey Oke, DVM, MSc
May 04 2010, Article # 16295

In a letter to veterinarians dated April 28, Brett Whitehead, Director, Equine and Ag Retail Business, of Intervet Schering-Plough Animal Health, encouraged practitioners to return all PreveNile vaccine. The recall was initiated after an increased incidence in the number of adverse events following vaccination with currently marketed serials of PreveNile.

The company noted in the letter that Intervet Schering-Plough has notified the USDA’s Center for Veterinary Biologics about this recall action.

West Nile virus (WNV) is an important neurological disease of horses in North America characterized by a wide array of clinical signs that include fever, ataxia (incoordination), depression, behavioral changes, weakness or partial paralysis, recumbency, and death. The mortality rate is an estimated 33%, and horses that do survive can exhibit residual effects (e.g., gait abnormalities, behavioral changes).

The disease is transmitted primarily by mosquitoes. While prevention can include reducing mosquito numbers and exposure of horses to mosquitoes, the most important means of preventing WNV infections is vaccination. The American Association of Equine Practitioners (AAEP) considers the WNV a core vaccine and assures horse owners and veterinarians that it is “an essential standard of care for all horses in North America”.

Currently, only three WNV vaccines are available. PreveNile is a modified live chimeric non-adjuvanted vaccine that is labeled for the prevention of disease. In clinical trials, PreveNile was 100% effective and 99.9% reaction-free, and it was deemed safe to use in foals four months of age and older. Read the data.

According to Sharon Dilling, spokesperson for Intervet/Schering-Plough Animal Health, Manager of Global Communications for US Animal Health, “Reports included symptoms of acute anaphylaxis, gastrointestinal symptoms (colic), respiratory distress, and death following vaccination either with PreveNile alone or in combination with other vaccinations.”

Dilling assured consumers and horse owners that all reported adverse events were submitted to the U.S. Food and Drug Administration-Center for Veterinary Biologics (USDA-CVB).

Will this recall impact vaccine availability and place U.S. horses at risk for disease?

“Currently, the product is off the market until further notice, but there are other vaccines available,” reported Dilling.

Owners or veterinarians with questions or concerns regarding PreveNile or any other product manufactured by Schering-Plough Animal Health are encouraged to contact the Technical Service Department at 866/349-3497.

© 2010 – 2011, Linda Tellington-Jones. All rights reserved.

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