State of Utah Department of Agriculture and Food

First Case of West Nile Virus in
Utah Horse Reported

Tests conducted on a horse in Weber County have confirmed that the animal is infected with West Nile Virus (WNV). This is the first case of West Nile virus in a Utah horse this year. The horse was a five year old quarter horse gelding located in the Ogden area. The animal had not traveled outside the area for the past 12 months and was not vaccinated for WNV. The horse was euthanized due to the severity of the symptoms. Test samples were taken from the horses recently after they exhibited symptoms of WNV. The samples were tested at the State Veterinary Diagnostic Laboratory in Logan, Utah.

WNV is not transmissible from horses to humans.

Human safety measures

PROTECT FROM DUSK UNTIL DAWN. That is when mosquitos that carry the virus are most active, so take precautions to prevent mosquito bites.
USE REPELLENT WITH DEET. For adults, use repellents containing DEET at 30-35% concentrations. For children 2 months to 12 years, use repellents containing 10% or less DEET. Do not use on children under the age of 2 months.
TAKE COVER. Wear protective clothing, long-sleeved shirts and long pants while outdoors.
REMOVE STANDING WATER. Drain standing water - this is where mosquitos lay eggs. This includes tires, cans, puddles, barrels, flower pots, etc.

West Nile Virus is rare, but if you have symptoms including high fever, severe headache and stiff neck, contact your local health care provider.

Equine safety measures

The Utah Department of Agriculture and Food (UDAF) is strongly advising horse owners throughout the state to continue to protect their animals by vaccinating them for the West Nile Virus if they haven’t done so already. The UDAF also advises all Utahns to take necessary precautions to protect themselves from WNV.

The UDAF has been advising horse owners to administer two vaccination shots for the past several weeks. It is now advisable to administer a booster shot for added protection. The WNV vaccine is available from local veterinarians.

Utah now joins Wyoming, Colorado, New Mexico, Arizona, Nevada, California and Idaho as states reporting WNV in horses this year.
The most common sign of West Nile virus in horses is weakness, usually in the hindquarters. Weakness may be indicated by a widened stance, stumbling, leaning to one side and toe dragging. In extreme cases, paralysis may follow. Fever is sometimes evident, as are depression and fearfulness. WNV causes encephalitis and affects the central nervous system.

Horse owners who suspect West Nile viral infection of their animal should contact their veterinarian immediately. Approximately 1/3 of horses that show signs of the illness will die. Eighty percent of WNV in horses occurs in the months of August and September. Horse owners who have not already done so should contact their veterinarian and have their horses vaccinated, though vaccination after exposure may not protect the horse against the disease.

The equine vaccine requires two doses and takes approximately five weeks to offer protection from the disease. Once vaccinated, yearly booster shots are necessary.

Horse owners can protect their animals by applying approved repellants to the animals and by controlling mosquitoes and mosquito breeding areas. Horse owners may also protect the animals by putting them in the barn or other enclosed structures.

For more information about the West Nile Virus, please visit the Utah Department of Agriculture and Food’s web page or the Utah Department of Health’s web page.

If you have questions concerning your health or believe you may have contracted West Nile Virus, please contact your physician.

West Nile Virus has spread rapidly across the country since first being discovered in New York in 1999. The most common way people and animals can contract the disease is through a mosquito bite. Only about 20 percent of people infected with the WNV show symptoms of the infection, which can include headaches, body aches and a mild fever. Less than one percent of those infected will develop a serious illness, such as encephalitis and meningitis. There is increasing risk of illness with increasing age. However, there is no age at which there is no risk.

Tests on blood samples taken from sentinel chickens and horses were conducted at the Utah Veterinary Diagnostic Laboratory in Logan.

Several bird species serve as the reservoirs for the disease. Mosquitoes transmit the disease from those birds to other birds, horses, humans, and other animals. Horses and humans are dead end hosts for the disease. That means the disease cannot be transmitted from an infected horse or human.

Posted August 5, 2005