The disease is carried by mosquitoes that have bitten infected birds. (Jim Gathany / CDC )
It’s a bad West Nile virus season.
Here are some basic facts about the virus and some things you can do to protect yourself, gleaned from a paper in the Journal of the American Medical Assn. by Dr. Robert W. Haley of the division of epidemiology at the University of Texas Southwestern Medical Center.
Most people don’t get sick from the virus, which is carried by mosquitoes that have bitten infected birds. About 80% of those people who are infected by a mosquito bite will not even have any symptoms. And once someone has been infected, thereafter he or she is immune. Healthy young adults and children rarely sicken.
Symptoms in the remaining 20% include fever and headache -- these are general enough that you quite possibly had West Nile and didn’t even know it.
But human beings are among the handful of creatures that can sometimes get very sick from infection with the virus. (Only people, blue jays, crows and horses tend to die, Haley writes.) That happens in about one in 150 cases when the virus infects the brain and spinal cord, leading to an array of symptoms such as confusion and other thinking problems, weak muscles, stiff neck and movement disorders.
In cases of so-called West Nile neuroinvasive disease, there are no specific medications, just good medical and nursing care. The death rate in such cases is somewhere between 4% and 18%.
West Nile neuroinvasive disease generally occurs in people who are over the age of 50.
There’s no vaccine against West Nile, so the way to protect yourself is to try to avoid getting bitten by a mosquito. That’s particularly important for people over 50 or with chronic medical conditions.
Make sure there isn’t standing water in your yard;
Make sure your doors and windows have well-fitting screens;
Stay inside between dusk and dawn;
Cover up (long pants and sleeves);
Use DEET insect repellant when outdoors.
You need not fear Fido or Fluffy — you’re not going to get West Nile from your pet. You also can’t get West Nile from other people. A mosquito bite is key to transmission.
You can read much more information about West Nile at the website for the Centers for Disease Control and Prevention, including a fact sheet, maps and more detailed information for physicians.
The California Department of Public Health is also a good source of information, including ways in which the public can help by reporting dead birds.