   West Nile Virus - September 4, 2002 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County You have probably heard the recent predictions that West Nile virus (WNV) is headed toward Arizona and may be here by December 2002. Even though this subject is not directly related, I thought readers would be interested in what is known about West Nile virus and some practices that are associated with risk. Preparing ourselves now will certainly allow us to be ready when the disease arrives in Arizona. WNV is spread by the bite of an infected mosquito, and can infect people, horses, many types of birds, and some other animals. Most people who become infected with West Nile virus will have either no symptoms or only mild ones. However, on rare occasions, WNV infection can result in a severe and sometimes fatal illness known as western equine encephalitis (WEE). The risk of severe disease is higher for persons 50 years of age and older. It is unknown if immunocompromised persons are at increased risk for WNV disease. There is no evidence to suggest that WNV can be spread from person to person or from animal to person. WNV was identified in the eastern U.S. in 1999. While the virus has been spreading westward and now can be found in nearly every state east of the Mississippi River and many states that border it, it has not yet made its way to the west. Because WNV can be transmitted to people by mosquitoes that feed on infected birds, mosquitoes, sentinel chickens and dead birds are being monitored on a regular basis in order to detect its presence. Thus far, all samples for WNV surveillance have been negative. However, the Arizona Department of Health Services, statewide physicians and veterinarians, and the University of Arizona Veterinary Diagnostic Lab are all on the lookout for cases of infected horses and/or birds. Symptoms of WEE and other varieties of sleeping sickness in horses include neurological signs such as depression, lack of coordination, circling, and head pressing. The affected horse may go down and be unable to rise. In 20% to 50% of the cases, the disease results in death. Vaccines are available to protect horses from viral encephalitis. WEE virus is combined with other varieties of sleeping sickness virus, such as EEE, for horse vaccination. The Venezuelan variety of the virus, currently not present in the U.S., is also available as a vaccine. Normally, it would not be used unless the disease appeared to be spreading north from other countries where it is found. Although a WNV vaccine is also available, recommendations for its use will not be made until it appears to be making its way to the western U.S. The majority of people who become infected with WNV do not have any symptoms. A small group will develop mild or moderate flu-like symptoms such as headache, fever and body aches. Some individuals, including the elderly, may experience more severe symptoms, including higher fever, neck stiffness, and encephalitis or inflammation of the brain. Once West Nile Virus gets to our area, it will stay here and we will need to cope with it. Human illness from West Nile virus is rare, even in areas where the virus has been reported. The chance that any one person is going to become ill from a mosquito bite is low. You can further reduce your chances of becoming ill by protecting yourself from mosquito bites. This can be done by using a mosquito insecticide containing DEET and wearing loose-fitting long sleeved shirts and long pants. In addition, eliminate standing water, remove, cover or properly store objects which may collect water such as old tires, coolers, cans, buckets, and barrels, and change the water in bird baths and water troughs at least twice a week. This article is not designed to make people upset or scared. It is simply to inform you about an introduced disease and how to cope with it. More information about WNV can be found at the Centers for Disease Control and Prevention web site: www.cdc.gov. The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@verdeonline.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://ag.arizona.edu/yavapai/anr/hort/byg/. |