USDA Advisory Says West Nile Virus Vaccine Safe for Use

From the United States Department of Agriculture
"Some recent stories have suggested that the Fort Dodge Animal Health West Nile Virus Vaccine approved by the U.S. Department of Agriculture (USDA) may cause pregnant mares to abort or give birth to deformed foals. The misleading information in those articles has sparked many anxious phone calls from horse owners, veterinarians, and others involved with horses. Unfortunately, as a result, USDA is concerned that horse owners may not use an effective preventive measure against West Nile virus available to them, that of vaccinating their horses.

"Horse owners should be assured that the vaccine is safe, and it should be used as protection against West Nile virus. Millions of doses of the vaccine have been used since USDA's Center for Veterinary Biologics approved its use in 2001.

"The Center for Veterinary Biologics, within USDA's Animal and Plant Health Inspection Service, maintains a toll-free telephone hotline (800-752-6255) and a mailbox on its Web site ( and actively encourages veterinarians and other vaccine consumers to report problems with vaccines. To date, there have been a very small number of reports regarding a possible association between the use of West Nile virus vaccine and abortions, birth defects, or other reproductive anomalies or failures. It does not appear that there is a relationship between West Nile virus vaccine use and these reproductive problems or any other major problems. The Center and the vaccine manufacturer will continue to collect, monitor, and track the performance of this vaccine.

"Since West Nile virus' detection in the United States in 1999, the number of horses affected by the virus steadily continues to grow. In 2002 alone, there were 14,717 equine West Nile virus cases. To help reduce the number of cases in 2003, USDA recommends that horse owners not only vaccinate their animals but implement safeguards to prevent animals' exposure to mosquitoes, which spread the virus."