It is West Nile virus season in North America. It has become a recurring epidemic throughout the U.S. and is spread by infected mosquitoes. It flares up in the summer and continues into the fall.
West Nile virus first appeared in the United States in 1999. Since the original case was reported, more than 30,000 people have been diagnosed with the disease.
How Is West Nile Virus Spread?
The virus is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread the virus to humans and other animals through a bite.
What are the Symptoms?
People who contract this infectious disease usually have mild symptoms. Approximately 80 percent of people who are infected with the virus will not show any symptoms at all.
Up to 20 percent of the people who become infected have symptoms such as fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms usually last for a few days, although even healthy people have become sick for several weeks.
About one in 150 people infected with the virus will become severely ill. Their symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. Symptoms may last several weeks, and neurological effects may be permanent.
If West Nile virus enters the brain, however, it can be deadly. It may cause inflammation of the brain, called encephalitis, or inflammation of the tissue that surrounds the brain and spinal cord, called meningitis. Older people are most at risk for this complication.
When Do Infected People Get Sick?
Symptoms typically develop between three and 14 days after a bite by an infected mosquito.
What is the Treatment?
There is no specific treatment. In more severe cases, people usually need to go to the hospital where they can receive supportive treatment, which may include intravenous fluids, help with breathing and nursing care.
How Can I Prevent West Nile?
There are no specific vaccines or treatments. The easiest and best way to avoid the disease is to prevent mosquito bites.
- Many mosquitoes are most active at dusk and dawn. Wear long sleeves and pants at these times, or consider staying indoors during these hours.
- When you are outdoors, use insect repellent containing an EPA-registered active ingredient. Follow the directions on the package.
- Get rid of mosquito breeding sites by emptying standing water from flowerpots, buckets or barrels. Change the water in pet bowls frequently.
- Use screens on windows to keep mosquitoes out.
- If you find a dead bird, do not handle the body with your bare hands. Contact your local health department for instructions on reporting and disposing of the body.