West Nile Virus
Your Health Information
Medical experts believe West Nile virus is a seasonal epidemic in greater North America. WNV is a potentially serious illness that flares up during summer months, and continues into fall. WNV affects the central nervous system, with varying symptoms:
- Approximately 80 percent of people who are infected with WNV will not show any symptoms at all.
- Up to 20 percent of the people who become infected will display mild symptoms, including headache, fever, body aches, nausea, vomiting, and at times swollen lymph glands or a skin rash on the chest, stomach and back. These symptoms typically last less than a week.
- The most severe symptoms can include headache, high fever, neck stiffness, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent. About one in 150 people infected with WNV will develop severe illness.
Typically, people develop symptoms of WNV between 3 and 14 days after they contract the virus.
How is WNV Spread?
WNV is not spread through casual contact such as kissing or touching a person who is infected. Generally, WNV is spread through the bite of an infected mosquito.
Mosquitoes are WNV carriers that become infected when they feed on infected birds. Infected mosquitoes can then spread WNV to humans and other animals when they bite.
In a very limited number of occurrences, WNV also has spread through organ transplants, blood transfusions, breastfeeding and even from mother to baby during pregnancy.
How Is WNV Infection Treated?
There is no specific treatment for WNV infection. In cases with mild symptoms, people experience symptoms such as fever and aches that pass on their own. In more severe cases, people usually need to go to the hospital where they can receive supportive treatment including intravenous fluids, help with breathing and nursing care.
What Is the Risk of Catching WNV?
Relatively few mosquitoes actually carry WNV. Additionally, less than 1 percent of people who are bitten by infected mosquitoes ever develop any symptoms of the disease.
People who spend a lot of time outdoors are more likely to be bitten by an infected mosquito. They should take special care to avoid mosquito bites. People over the age of 50 should also take special care to avoid mosquito bites, as they are more likely to develop serious symptoms of WNV if they do get sick.
What Can I Do to Prevent WNV?
Preventing mosquito bites is the easiest and best way to avoid contracting WNV.
- When you are outdoors, use insect repellents containing DEET (N, N-diethyl-meta-toluamide). Always follow the directions on the package.
- Consider staying indoors during dusk and dawn when many mosquitoes are most active. Or, you may consider use insect repellent and wear long sleeves and pants. Light-colored clothing can help you see mosquitoes that land on you. Make sure you have good screens on your windows and doors to keep mosquitoes out.
- Change the water in pet dishes and replace the water in birdbaths weekly. Empty standing water from flowerpots, buckets and barrels to get rid of mosquito breeding sites.
What Should I do if I think I have WNV?
People do not necessarily need to seek medical attention for this infection, as mild WNV illness improves on its own. If symptoms of severe WNV illness develop, such as unusually severe headaches or confusion, medical attention should be sought immediately. Severe WNV illness usually requires hospitalization. Women who are pregnant or are nursing mothers are encouraged to talk to their doctor if they develop symptoms that may signify WNV.
For more answers to questions about West Nile virus, visit the U.S. Center for Disease Control's website. http://www.cdc.gov/ncidod/dvbid/westnile/q&a.htm
