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.
Any person bitten by a mosquito infected with WNV is at risk. The mosquito most closely associated with the disease (northern house mosquito) breeds in the stagnant water of mud puddles, ditches, flower pots, old tires, clogged gutters, and similar reservoirs of water. It is important to apply mosquito repellent when participating in any outdoor activity — especially when fishing, camping, or boating at night. Wearing light-colored clothing with long sleeves and long pants helps prevent mosquito bites. Window screens on campers and boats should be kept “bug-tight” as should netting on tents and similar outdoor gear. Keeping a campsite neat and orderly and eliminating any potential mosquito breeding sites are always recommended. Electric “bug zappers” do not help since these devices attract more mosquitoes than they kill.
There is no evidence that WNV can be transmitted directly from birds or mammals to humans through direct blood contact. However, hunters are always urged to take proper precautions and wear rubber gloves when field dressing game.
Proper cooking kills the West Nile Virus. Consequently, there is no danger associated with eating well-cooked wild game that might be infected.
It is completely safe to feed and provide habitat for wild birds in Ohio. Residents are urged to clean birdbaths regularly (at least weekly); aerate backyard ponds or stock them with mosquito-eating species such as goldfish; and eliminate containers of stagnant water.
During the summer of 2002, West Nile Virus was responsible for widespread illness and death among Ohio’s birds-of-prey, especially hawks and owls. Anyone who encounters an ill raptor in the wild should take special care to avoid contact with the bird and call a local raptor rehabilitation center for assistance. A list of raptor rehab centers is available on the Ohio Department of Natural Resources (ODNR) web site. While WNV cannot be contracted through touch, the sharp beaks and claws of raptors pose a different kind of danger. People who encounter freshly dead birds with no other apparent illness or injury should alert the local health department. Health officials are currently monitoring deaths in Ohio’s bird population to track the progression of WNV. However, anyone handling dead wildlife, including raptors, should always wear rubber gloves. Dead birds should be double-bagged in trash bags and disposed of. Responsible public action coupled with responsible individual behavior is the best way to prevent the spread of WNV and keep Ohioans safe from this new disease.
The Ohio Department of Natural Resources at 614-265-1015 or 614-265-6860. Or visit the ODNR web site at www.dnr.state.oh.us and link to the WNV Work Group page for updated information on the disease.
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
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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