We're unable to sign you in at this time. Please try again in a few minutes.
We were able to sign you in, but your subscription(s) could not be found. Please try again in a few minutes.
There may be a problem with your account. Please contact the AMA Service Center to resolve this issue.
Contact the AMA Service Center:
Telephone: 1 (800) 262-2350 or 1 (312) 670-7827  *   Email: subscriptions@jamanetwork.com
Error Message ......
JAMA Patient Page |

West Nile Virus FREE

Janet M. Torpy, MD, Writer; Cassio Lynm, MA, Illustrator; Richard M. Glass, MD, Editor
JAMA. 2003;290(4):558. doi:10.1001/jama.290.4.558.
Text Size: A A A
Published online

West Nile virus (WNV) affects humans, birds, horses, and other animals. The virus is carried from infected birds (the host animal) to humans and other mammals through mosquito bites. When a mosquito bites, a small amount of blood is injected into the skin of the bitten person or animal. This infected blood can transmit WNV or other similar diseases.

West Nile virus is more commonly found in the eastern United States. West Nile virus disease activity has spread rapidly since 1999, when it was first reported in the United States. The main period of risk is from July through September, but cases have occurred from May through December. The outbreak of WNV infection in the United States during the summer of 2002 was the largest reported. There were 284 deaths and 4156 human cases of WNV infection reported in 2002. The July 23/30, 2003, issue of JAMA includes articles about WNV.


  • Fatigue

  • Headache

  • Loss of appetite

  • Nausea or vomiting

  • Muscle aches

  • Rash

  • Fever

  • Confusion, delirium, or coma

Most people who become infected with WNV do not develop severe illness. Mild WNV infections usually last 3 to 6 days after an incubation (delay) period of 3 to 14 days after the initial exposure to the virus. Approximately 1 in 150 persons infected with WNV develops a more severe form of WNV infection, including encephalitis (inflammation of the brain). Some individuals with a severe WNV infection develop rashes, paralysis, inflammation of nerves, and seizures. Older persons are more susceptible to severe infection with WNV.


Special blood tests may be done by local or state health departments if your doctor suspects you might have WNV infection. Because WNV is a virus, antibiotics will not work to treat WNV infection. Persons who are ill with WNV infection usually require hospitalization for supportive care. There is currently no vaccine for WNV. Research studies are ongoing to find a way to immunize persons against WNV infection.


Preventing WNV transmission by mosquitoes is the most important way to decrease WNV infection in humans:

  • Drain all standing water where mosquitoes breed (birdbaths, old tires, flower pots, buckets, stagnant puddles or ponds).

  • Wear protective clothing when mosquito exposure is possible ((long sleeves, long pants, socks).

  • Use an insect repellant containing DEET on exposed skin.

  • Stay indoors during peak mosquito time (dawn, early evening).

  • Keep windows and screens in good repair.

Also, do not handle dead birds. More than 162 species of birds have been reported to have WNV infection. Crows have a particularly high death rate from WNV. Local and state health departments may collect dead birds to test them for the presence of WNV.



To find this and previous JAMA Patient Pages, go to the Patient Page link on JAMA’s Web site at http://www.jama.com. Many are available in English and Spanish.

The JAMA Patient Page is a public service of JAMA . The information and recommendations appearing on this page are appropriate in most instances, but they are not a substitute for medical diagnosis. For specific information concerning your personal medical condition, JAMA suggests that you consult your physician. This page may be photocopied noncommercially by physicians and other health care professionals to share with patients. Any other print or online reproduction is subject to AMA approval. To purchase bulk reprints, call 718/946-7424.

Sources: Centers for Disease Control and Prevention, National Institute of Allergy and Infectious Diseases, Environmental Protection Agency, National Pesticide Information Center





Also Meets CME requirements for:
Browse CME for all U.S. States
Accreditation Information
The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
Note: You must get at least of the answers correct to pass this quiz.
Please click the checkbox indicating that you have read the full article in order to submit your answers.
Your answers have been saved for later.
You have not filled in all the answers to complete this quiz
The following questions were not answered:
Sorry, you have unsuccessfully completed this CME quiz with a score of
The following questions were not answered correctly:
Commitment to Change (optional):
Indicate what change(s) you will implement in your practice, if any, based on this CME course.
Your quiz results:
The filled radio buttons indicate your responses. The preferred responses are highlighted
For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
Indicate what changes(s) you will implement in your practice, if any, based on this CME course.


Some tools below are only available to our subscribers or users with an online account.

0 Citations

Related Content

Customize your page view by dragging & repositioning the boxes below.

Articles Related By Topic
Related Collections
PubMed Articles