USDA issues conditional license for West Nile virus vaccine for horses

WASHINGTON – In 2000, seven states in the Northeast battled 60 confirmed equine cases of clinical illness due to infection with West Nile virus.

Of the 60 horses, 37 survived, but 23 died or were euthanized.

Just last week, the USDA issued a conditional license to Fort Dodge Laboratories of Fort Dodge, Iowa, 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 products to meet an emergency situation, limited market, local situation, or special circumstance.

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 in horses. 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.

The most common signs of West Nile virus infection in U.S. horses have been stumbling or uncoordination, weakness of limbs, partial paralysis, muscle twitching and death. Fever has been detected in less than one-quarter of all confirmed cases.

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.

The following states have approved the conditional use as of presstime: Alabama, Arizona, Connecticut, Delaware, Georgia, Idaho, Kansas, Louisiana, Maryland, Maine, Michigan, Minnesota, Mississippi, North Dakota, New Hampshire, New Jersey, Nevada, New York, Ohio, Pennsylvania, West Virginia and Florida. Other states may also seek approval; check with your veterinarian.

In Pennsylvania.

West Nile virus was detected in Pennsylvania for the first time last year and for the first time in Ohio this year.

Last year, West Nile virus was found in 19 Pa. counties: Bucks; Bradford; Chester; Cumberland; Dauphin; Delaware; Erie; Franklin; Lehigh; Montgomery; Northampton; Philadelphia; Pike; Schuylkill; Susquehanna; Tioga; Union; Wyoming; and York. It was identified in 32 birds, 45 mosquito pools and a horse.

“Similar to people, horses only become infected with West Nile virus after being bitten by an infected mosquito,” said Pa. Agriculture Secretary Sam Hayes.