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WASHINGTON, August 1, 2001 The U.S. Department of Agriculture announced today that it has issued a conditional license to Fort Dodge Laboratories, Inc., of Fort Dodge, Iowa, a division of American Home Products, Inc. for a vaccine intended to aid in the prevention of disease in horses caused by West Nile virus.
USDA's Animal and Plant Health Inspection Service issues conditional licenses for veterinary biologics products to meet an emergency situation, limited market, local situation, or special circumstance. The special circumstance addressed here is the need for a product to aid in the prevention of disease caused by West Nile virus.
Under these regulations, a product that is shown to be pure and safe and demonstrates a reasonable expectation of efficacy may be licensed while data to establish efficacy and potency are still being obtained.
West Nile virus is a mosquito-borne virus that was first detected in the United States in 1999. The virus, which can cause encephalitis, or inflammation of the brain in animals and in some cases, humans, has been found in Africa, western Asia, the Middle East, the Mediterranean region of Europe, and most recently in various parts of the eastern United States.
West Nile virus infection in horses may include both central nervous system and peripheral nervous system signs. Although horses can be infected by the virus, there is no documentation that infected horses can spread the virus to uninfected horses or other animals. In 1999 and 2000, 85 horses were infected with the virus, and 32 of these cases resulted in death.
The most common signs of West Nile virus infection in U.S. horses have been stumbling or incoordination, weakness of limbs, partial paralysis, muscle twitching and death. Fever has been detected in less than one-quarter of all confirmed cases.
Conditional licenses are generally issued with restrictions and for a limited period of time. At the end of the conditional license period, data obtained in support of the product's efficacy, potency, and product performance are evaluated to determine if the conditional license should be renewed or if a regular product license may be issued.
In keeping with these regulations, the product described above has been issued a conditional license for one year. The product is restricted to use by a veterinarian in those states where use of the product has been approved by the appropriate state regulatory authorities.
Horse owners planning to ship their animals to other countries should be aware that vaccinated animals may not meet the import requirements of those countries due to the presence of certain antibodies in their blood. While the presence of this antibody is not permanent, it could lead to complications in shipping the horse.
NOTE: USDA news releases, program announcements, and media advisories are available on the Internet. Access the APHIS Home Page by pointing your web browser to http://www.aphis.usda.gov/ and clicking on "APHIS Press Releases." For Horse Owners needing more information about the vaccine, contact your local Veterinarian!