I was bitten by a mosquito — West Nile virus?

Dear Once Bitten,

In 1999, West Nile virus appeared in the United States. Though this was the first time the virus was seen in North America, West Nile has since spread across the Western Hemisphere. Most infected people either show no symptoms or have mild to moderate fever, headache, body aches, and general overall tiredness. They may also have swollen lymph nodes or a rash. However, about 1 out of 150 people infected with the virus will develop severe West Nile disease, in which the virus causes inflammation of the brain, membrane around the brain, and/or spinal cord. Symptoms can include:

• Headaches
• Fever
• Muscle weakness
• Stiff neck
• Nausea and vomiting
• Muscle weakness
• Confusion
• Tremors
• Convulsions
• Coma

The elderly and people with compromised immune systems are at the highest risk of developing severe illness from the virus. There is no cure for the infection itself, but most people will clear the infection on their own. Treatment for people with West Nile-related neuroinvasive disease involves what is called supportive care: fluids, bed rest, preventing secondary infections, respiratory management/support, and careful monitoring by a health care provider.

Interestingly, human beings are just incidental in the life of the virus. It has a complex life cycle involving birds and mosquitoes. Occasionally, as an "innocent bystander," a person may get infected. The virus cannot be passed from person to person, nor between other animals and people. In other words, the virus does not "need" us in order to live.

It's also important to know that the virus isn't carried by all mosquitoes and only a very few people actually become ill with this infection. Others may get an extremely mild form of the West Nile virus, but their immune system clears the infection without much to-do. Most people will never actually get exposed to the virus at all. Overall, try to limit your exposure to mosquitoes in order to avoid being bitten. For information on the surveillance of the West Nile Virus, check out the National Center for Infectious Diseases of the Centers for Disease Control and Prevention: West Nile Virus Homepage.

The most important thing to do if you've been bitten by a mosquito is: don't panic! If you develop symptoms that you are concerned about, consult with your health care provider. Otherwise, enjoy the summer, even if you get a few mosquito bites.