The first human cases of West Nile virus were reported last week in Indiana’s Madison and Huntington counties. This isn’t unexpected at this time of year, and Indiana joins 44 other states reporting West Nile virus (WNV) in mosquitoes, birds, or humans.
WNV was first isolated in 1937 from a feverish patient in the West Nile District of northern Uganda. The first epidemic level of human infection was in Israel in 1951. WNV hit New York City in 1999, and within three years the virus had spread to the West Coast. Over the years the symptoms of WNV infection have become progressively more serious.
Humans contract WNV through the bite of a mosquito which has previously bitten an infected bird. There are two main groups of mosquitoes, Nuisance and the Culex. Nuisance mosquitoes prefer flooded and swampy areas, recreational areas and parks/homes, and the bite is noticeable (painful), thus alerting the victim of possible infection risk. The Culex mosquito is the one that can carry WNV, and it prefers standing water like what’s found in old tires and children’s swimming pools after a summer rain. Unlike the Nuisance mosquito, the bite of the Culex is barely noticeable, thus increasing the chances that you could be at risk without evening knowing you had been bitten.
People may start to show symptoms of WNV infection within 3-15 days of a mosquito bite. The disease can be anywhere on a wide spectrum of severity. Mild symptoms can include low grade fever, headache and muscle aches, or eye irritation, not unlike many other viral infections including mild cases of influenza. However, WNV can cause serious infections with high fever, aches, disorientation, convulsions, coma, paralysis, and even death.
WNV has been found in most all age groups from the youngest to the oldest, but is more common over 50 and in those with weakened immune systems. What about other animals? Other animals can get WNV and the spectrum of disease is similar to humans. Even though no cases have occurred by transmission from animals to humans, the CDC recommends avoiding bare hand contact with sick or dead animals.
What can we do to minimize the risk of WNV this summer and fall? Here are a few recommendations:
• Do not allow standing water on your property and keep brush trimmed. Properly dispose of old tires, swimming pools, or other containers that can hold water. Keep swimming pools and wheelbarrows turned over when not in use.
• Clean clogged roof gutters.
• Keep larger swimming pools well chlorinated, and don’t let water stand on pool covers.
• Use an insect repellent containing DEET. Swatting the little pests is effective if done before the bite.
• Wear proper clothing to cover the skin and keep mosquitos out.
Pregnant women are not at higher risk, but there is a real but very low risk of transmission to the fetus. Pregnant women can and should use mosquito repellent to help reduce risk. WNV may be transmitted via breast milk.
Although WNV antibody and virus tests are available, these are not usually used in the setting of mild symptoms, and a negative test does not insure absence of the virus. There are no vaccines or specific treatment for WNV infections. The most serious infections involve infection in the brain (encephalitis), and hospitalization for supportive care is necessary. Patients who recover can have lingering headaches and fatigue, but many recover completely. If you think you have symptoms of a viral infection, always see your primary care provider for further evaluation of your risks.
Dr. Fleming is the Medical Director of The Jane Pauley Community Health Center (closely affiliated with Community Health Network). Ideas for this column can be e-mailed to Dr. Fleming at AskDrFleming@gmail.com. Or you can write your medical questions to Dr, Fleming at AskDrFleming, 8931 E. 30th Street, Indianapolis, IN 46218. On written correspondence, please include your name and city (names will not be published).