Banner Health Services  

West Nile Virus

Mike Soubolle  

Michael Saubolle, Ph.D, medical director of the Infections Disease Laboratories at Banner – University Medical Center Phoenix.

Question: What is West Nile virus infection?

Answer: In the United States, the West Nile virus infection is seen primarily during the summer months, coinciding with higher bird and mosquito activity. The virus that causes West Nile illness normally infects birds, which act as carriers of the virus. Mosquitoes become infected when they get their blood meal through biting infected birds, and then themselves act as transmitters of the virus when they bite other animals, including horses and humans. Thus, the West Nile virus may be a serious health threat and is of great concern to public health officials.

Eight of 10 infected humans will either show no symptoms or will have only very mild illness. Some will develop flu-like symptoms: possible headache, fatigue, weakness, body-aches, swelling of glands and/or fever. Symptoms may remain from a few days to several weeks.

In a few cases, symptoms may become more severe and on rare occasions the virus may even cause encephalitis, an inflammation of the brain. Patients with such progression of disease may show additional symptoms such as higher fever, increased headache, nausea, vomiting, stiffness of the neck, disorientation and lethargy. Persons with more severe disease should seek immediate medical attention. In patients with significant symptoms, the diagnosis of West Nile virus infection can be made by a blood test performed by a clinical laboratory. Although there is no specific treatment for the virus, supportive medical care is important in severe cases.

West Nile virus infections can be decreased greatly by using mosquito repellents, staying indoors during periods of high mosquito activity (evenings, nights) and eliminating any unhealthy standing water which aids mosquito breeding.

Page Last Modified: 02/27/2015
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