The equine industry called out for a way to protect its horses from the deadly neurological disease West Nile virus (WNV), and researchers and federal authorities responded. The United States Department of Agriculture (USDA) and Fort Dodge Animal Health announced on Aug. 1 the approval and release of the very first WNV vaccine for horses. The virus had already begun to appear in horses in the panhandle of Florida (see story on this page). This is the southernmost and earliest onset of equine cases in the three years since the virus first appeared in the Western Hemisphere. To be conditionally licensed, the vaccine had to meet federal standards of purity, safety, and reasonable expectation for efficacy. Each state will have to give approval for the vaccine’s use, and most states have conditionally licensed products available only through a veterinarian.

“There’s no question that Florida will need every dose it can get its hands on to protect its horse population,” said Lee Coffman, DVM, Director of the Division of Animal Industry in Florida’s Department of Agriculture and Consumer Services. He said the virus is moving steadily south, and although the virus is currently active in an area with a moderate density of horses, central and southern Florida have many more horses which would be susceptible to the virus.

West Nile virus hit the northeastern United States in 1999, baffling public health officials and epidemiologists when it killed birds, horses, and humans. Officials are still not sure how the disease was introduced in the United States, but they believe after studying the genetic makeup of many virus samples it was a single introductory occurrence. The virus is spread by the bite of an infected mosquito and harbored by birds. West Nile virus killed 36% of its diagnosed equine victims in 1999, and 38% in 2000. Officials hope the vaccine will give veterinarians the upper hand in preventing the appearance of equine cases, which typically do not occur until late summer or early fall. (Learn more about the history of WNV in this country at https://thehorse.com/wnv).

In February of 2000 when the USDA was forming its WNV Strategic Plan, authorities agreed to expedite the processing of applications for conditional licensure of a WNV vaccine. Several pharmaceutical companies were working to make the vaccine available to the horse industry, but Fort Dodge was the first to complete field trials to test the safety of the vaccine in horses and submit their product to the USDA Veterinary Services’ Center for Veterinary Biologics in Ames, Iowa, for conditional approval