9.14.2006 - 08:06am ET

(CSRwire) An equine vaccine developed by Akzo Nobel's animal health business Intervet, which is indicated for use in horses at risk from West Nile virus has been approved by the United States Department of Agriculture (USDA) for use in the United States.

PreveNileTM is the first one-dose modified-live virus vaccine to be registered in the United States for the prevention of viremia (the presence of a virus in the blood) caused by West Nile virus (WNV) infection in horses.

The virus--which can also be contracted by humans--is primarily spread by mosquitoes. In 2002 an outbreak in the United States seriously affected the horse population, as well as killing almost 300 people.

"We are quite excited about what this new technology can offer in terms of enhanced efficacy against this life-threatening disease in horses," said Intervet General Manager Ruurd Stolp. "In challenge studies, 100 percent of vaccinated horses were protected from fever and the presence of virus in the bloodstream."

In 2005, there were 1,075 reported cases of equine WNV in the United States. Since 1999, more than 30 percent of the cases of WNV diagnosed in horses have resulted in death.

Infection does not always lead to signs of illness in people or animals, but horses are susceptible to contracting the disease. In horses that do become clinically ill, the virus infects the central nervous system and may cause symptoms of encephalitis (inflammation of the brain).

"As the world's largest animal vaccine producer, Intervet is continually striving to develop innovative drugs for the global animal health market," added Stolp. "PreveNile is the latest in a series of significant products to have emerged from our strong pipeline."

Commonly found in Africa, west Asia and the Middle East, WNV has spread to the Caribbean and Latin America via infected mosquitoes and birds. The disease was unknown in the Americas until 1999, when an outbreak killed seven people in New York.

Approval for PreveNile--the only one-dose USDA-approved equine WNV vaccine--comes just days after Intervet was granted an EU license for its Nobilis Influenza H5N2 vaccine, which protects birds against the current H5N1 field strain of avian flu.