As the Midwest moves into the dog days of summer, many of us are naturally heading outdoors. Beaches, parks and backyards are packed with Wisconsinites soaking up the sun and enjoying all that the state has to offer. But while we’re outside appreciating the state’s brief spell of hot weather, local health authorities are reminding us to be aware of a new threat to our health. West Nile Virus has been introduced to Wisconsin, and apparently it’s here to stay.
West Nile Virus was first discovered in 1937 in the West Nile area of Uganda, but it didn’t arrive in North America until the summer of 1999, when it was found in the New York City area. Sixty-two people were hospitalized with the infection, and 7 died. By last summer the disease had spread to several more southeastern states; sixty-six people contracted the virus and 9 died. Even in Wisconsin, West Nile Virus was found in 58 birds in the summer of 2001, most of them in Milwaukee County.
This year, West Nile Virus has been found in birds in states throughout the southeast, and has continued moving into the Midwest. Wisconsin’s first documented virus-positive bird was found on Milwaukee’s south side on June 25. Mohammad Almoujahed, MD, Assistant Professor of Medicine in the Medical College of Wisconsin’s Division of Infectious Diseases, tells HealthLink, “This expansion of West Nile Virus indicates that it is permanently established in the Western Hemisphere.”
No Human Cases in Wisconsin
Although no humans in our state have been confirmed with West Nile Virus, several people in Mississippi, Texas and Louisiana have been infected this summer. Dr. Almoujahed reports that in most people, West Nile Virus brings on mild flu-like symptoms such as fever, body aches, headache and sometimes a rash and swollen glands. But in rare cases, the virus can cross the blood-brain barrier and produce encephalitis, a swelling of the brain and spinal cord. In these cases, the infection can be fatal. There is currently no human vaccine for West Nile Virus, and no specific medicine available to treat the infection.
Local health officials say that over the next two years, West Nile Virus will firmly establish itself and spread throughout Wisconsin, becoming more common in birds, horses and other animals, which puts humans at a greater risk for contracting the infection. It is important to remember that the virus is only transmitted by the mosquitoes that feed on these birds and animals, not by the birds and animals themselves. There has not been a documented case of bird-to-human, horse-to-human, or human-to-human transmission of West Nile Virus.
But caution is still very important, and authorities urge people to stay away from dead birds or animals, or to handle the bodies without touching them. In Wisconsin, the virus is most commonly found in crows and blue jays, and the state Department of Natural Resources has facilities available for people who want to bring in sick or dead birds for testing. If you come across a dead bird and want to have it tested, call your local DNR office or health department for locations and specific instructions.
Along with the DNR, the Milwaukee County Zoo is also helping out in the fight against mosquito-borne infection by joining the American Zoo Association’s West Nile Virus surveillance program. Zoo staff members run West Nile Virus tests on any outdoor birds or animals that are sick, and they are even using stored blood samples to check for possible West Nile Virus infection in animals that have not shown any symptoms. Since the virus was first recognized by officials at the Bronx Zoo in the 1999 New York outbreak, Milwaukee County Zoo veterinarians are more than willing to help us understand how it affects birds, animals and humans.
Infection Rare and Usually Mild
The introduction of West Nile Virus to Wisconsin has unfortunately sent some residents into panic mode, but it’s important to remember that infection is quite rare and the majority of cases are mild. Dr. Almoujahed recommends that anyone who develops symptoms such as high fever, confusion, muscle weakness and severe headaches contact their health care provider immediately. The doctor notes, “The chance that you will become severely ill from one mosquito bite is extremely small. In areas where West Nile virus has been found, very few mosquitoes (less than 1%) become infected with the virus, and less than 1% of people who get bitten and become infected will become severely ill.” As with many illnesses, the elderly and those with weakened immune systems run the highest risk of severe disease. When illness from West Nile Virus does occur, it takes from 3 to 15 days after being bitten by an infected mosquito for symptoms to appear.
Protect Yourself from Mosquitoes
The most important way to prevent West Nile Virus is to avoid being bitten by mosquitoes. Mosquito repellants with the ingredient DEET (N,N-diethyl-3-methyl-benzamide) have been shown to be the most effective in keeping mosquitoes away from humans. Use a repellant that’s appropriate to your environment and activities. More mosquitoes means higher risk, so choose your product carefully. Some contain higher concentrations of DEET than others; labels will typically specify how to use the product and how long it will last once applied.
Additionally, Dr. Almoujahed recommends wearing protective clothing such as long pants, loose-fitting long-sleeved shirts and socks when outdoors, and keeping window screens in good repair when indoors. Getting rid of any standing water is also a very important step, as it eliminates a prime breeding ground for mosquitoes. Taking common-sense steps to avoid mosquito bites will greatly reduce your chances of being infected.
