It looks like the West Nile virus, which is transmitted to humans by mosquitoes via birds, is here to stay. It's become a continuing story in both the print and broadcast media. So here's the best current information I have, most of which comes from the Center for Disease Control (CDC).
West Nile virus commonly occurs in humans, other mammals, and birds in Africa, eastern Europe, west Asia, and the Middle East. It was first identified in a woman in the West Nile District of Uganda in 1937. The source of the U.S. form is unknown, but it's genetically related to strains from the Middle East. Possible sources include tourists, businessmen, and military personnel who picked up the infection while abroad.
The disease caused by this virus, West Nile encephalitis, is an inflammation of the brain and is closely related to St. Louis encephalitis, which also occurs in the U.S.
West Nile virus was first detected here in 1999 in the New York City area, when 62 severe cases were diagnosed and seven people died. In 2000, 21 cases and two deaths were reported; last year there were 66 human cases and nine deaths. As of August 7 this year, five people have died and 94 other cases have been confirmed in Louisiana , Mississippi, and Illinois. Other cases are suspected in Texas and Arkansas. Dr. Julie Gerberding, director of the CDC, reports that, "So far we have no documented activity of West Nile virus west of a line that extends roughly from about Winnipeg to Houston."
To date, the virus has been detected in bird and humans in 34 states and Washington, D.C. There are no reliable estimates of the number of cases worldwide.
This year's West Nile outbreak began in June in Louisiana. Previously the first cases were reported in August. Perhaps the warmer southern climate gave the disease a head start when it finally reached the Gulf states. Dr. Jim Hughes, director of the CDC's National Center for Infectious Disease said, "The disease will not necessarily behave the same in all geographic areas."
West Nile virus is transmitted by a variety of mosquitoes including the common house mosquito, Culex pipiens. More than 70 species of birds, including crows and blue jays, serve as reservoir hosts and often die from the infection. Many states monitor caged chickens to detect the occurrence of the virus in specific areas.
West Nile virus is likely here to stay, so we must learn to deal with it. Symptoms include fever, headache, confusion, body aches, and sometimes rashes and swollen lymph glands.
Fortunately, and this is important, your chances of coming down with West Nile virus are slim. According to the CDC, less than one percent of those infected with the virus develop a serious illness, and fatalities occur in only three to 15 percent of those who become seriously ill. The elderly and anyone with a depressed immune system are at greatest risk.
If you've been bitten by mosquitoes and have symptoms, see your physician. The disease's incubation period (time from infection to onset of symptoms) is three to 15 days.
The best protection against West Nile virus is to reduce contact with mosquitos. Dr. Gerberding pointed out that, "...people need to appreciate some common sense measures that individuals can take that will help protect themselves and their families."
When outdoors, wear long pants and long-sleeved shirts as much as possible. Apply insect repellent to exposed skin. (The concentration of DEET should not exceed 10 percent for children.) Eliminate standing and stagnant water around the house. This is where mosquito larvae develop. Tires, buckets, flower pots, and bird baths are mosquito heaven. But you can continue to maintain a bird bath by simply emptying, cleaning, and replenishing the water every three days to disrupt the mosquitos' life cycle during the larval stage.
Finally, if you're concerned about pet dogs and cats, evidence suggests these mammals experience very low infection rates.
For more information about West Nile virus, visit the CDC web site at www.cdc.gov or call the CDC toll-free at 1-888-246-2675.