West Nile Virus (WNV) is a viral disease previously seen only in Africa, Asia, and southern Europe. This virus can cause encephalitis or meningitis, infection of the brain and the spinal cord or their protective covering. For the past six years, WNV has caused disease in the United States.
In 1999, at least 62 people became seriously ill, and seven of those died. Since then, WNV has rapidly spread throughout North America. During the year 2000, 21 human cases of WNV encephalitis were reported in the United States, with two deaths. In 2001 there were 56 cases with seven deaths.
In 2002, 4,156 human cases of WNV encephalitis or WNV fever were reported, with 284 fatalities. During 2003, almost 10,000 human cases of WNV encephalitis and fever were reported from 46 states, with 208 fatalities. In 2004, there were some 2,500 human cases with 87 deaths, with the cases occurring primarily in the western United States. In 2005, there were 2,800 cases with 105 deaths.
In Ohio in 2005, WNV was reported in birds, mosquitoes, humans, and horses. There were 61 human and 15 horse cases identified. It is expected that WNV will continue to be a disease threat in 2006.
West Nile Virus is spread to people by the bite of an infected mosquito. The principal transmitter of West Nile Virus is the Northern House Mosquito (Culex pipiens). Mosquitoes first become exposed to the virus when they feed on birds that are infected with WNV. Once the mosquito is infected, it may transmit the virus to people or other animals when it bites them. Many birds can be infected with WNV, but crows and blue jays are most likely to die from the infection. Horses, too, are prone to severe WNV infection. People cannot get WNV from another person or a horse that has the disease.
Continued spread of this disease among wild birds and mosquitoes is anticipated. State, federal, and local agencies are working together to address the health risks of WNV to Ohio families and their animals. Public health officials found WNV in many species of birds, mosquitoes, and horses in 44 Ohio counties during 2005. Once this was known, mosquito control efforts were increased in those areas to protect people from the disease.
Scrap tires can be a prime breeding source for mosquitoes, including the Northern House mosquito, which can carry WNV. When discarded, tires can accumulate small pools of water, where adult mosquitoes will lay eggs. Over the course of one breeding season, thousands of mosquitoes can be generated from just one tire. If tires infested with eggs, larvae, or pupae are transported, the potential to spread mosquitoes carrying the virus increases. Breeding takes place in water-filled tires where eggs are laid and the larvae and the pupae can grow. Adult mosquitoes emerge from the water in as little as seven days after hatching.
Businesses such as retail tire sales locations, retreading operations, fleet maintenance garages, and motor vehicle salvage dealers routinely remove tires in the course of business. Ohio regulations allow such facilities to accumulate a limited number of scrap tires generated by their business operations, but the regulations also require them to control mosquitoes at their facilities. Ohio’s tire rules require that these facilities either keep water from accumulating in scrap tires stored at their site or apply either a larvicide or a pesticide to the tires each month from April to November of each year. Businesses choosing to treat scrap tires must maintain records to document their compliance with the rule requirements.
Scrap tires may also be found around farms and private residences. Scrap tires are often found mixed with other solid waste at open dump sites. Such sites often provide additional containers (such as discarded cartons, packaging, buckets, and more) that provide breeding locations for mosquitoes.
If you have scrap tires on your property, farm, or business location, you are responsible for making sure they do not create a nuisance. There are a number of ways to eliminate mosquito breeding in scrap tires:
People with mild infections may experience fever, headache, body aches, skin rash, and swollen lymph glands. People with more severe infections may experience high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, occasional convulsions, and paralysis. If you have any of these symptoms, contact your doctor.
Breeding sites can be eliminated by removing standing water available to mosquitoes. Here are some simple steps:
WNV was confirmed in Ohio in 2005. Infected mosquitoes, birds, horses, and humans were found in 44 Ohio counties. Therefore, the virus is present throughout the state. Contact your local health department or log on to the web sites listed here for the current status on WNV in Ohio and for more information:
Ohio State University:
prevmed.vet.ohio-state.edu/Extension/WestNile/WNV.htm
Ohio Department of Health:
www.odh.state.oh.us/ODHPrograms/ZOODIS/ZooMain1.htm
Click here for PDF version of this Fact Sheet.
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Keith L. Smith, Associate Vice President for Agricultural Administration and Director, OSU Extension TDD No. 800-589-8292 (Ohio only) or 614-292-1868