Do People With West Nile Virus Infection Eventually Return to Normal Health?

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The summary below is from the full report titled "Prognosis after West Nile Virus Infection." It is in the 19 August 2008 issue of Annals of Internal Medicine (volume 149, pages 232-241). The authors are M. Loeb, S. Hanna, L. Nicolle, J. Eyles, S. Elliott, M. Rathbone, M. Drebot, B. Neupane, M. Fearon, and J. Mahony.

What is the problem and what is known about it so far?

West Nile virus is spread by mosquitoes. Most people infected with the virus have no symptoms, but some develop flu-like symptoms, such as headache, eye pain, and upset stomach. Some may develop a more serious infection of their brain and spinal cord, causing loss of consciousness and paralysis. The extent to which people with these more serious symptoms can recover normal function has not been fully studied.

Why did the researchers do this particular study?

To determine the extent to which people with West Nile virus infection recover from their initial infection.

Who was studied?

156 people from Canada with West Nile virus infection.

How was the study done?

The researchers assessed the participants' physical and mental function as soon as possible after they were initially infected. They also measured the participants' mood and symptoms of fatigue. They then repeated the measurements regularly over time to see the extent to which function, mood, and symptoms of fatigue improved.

What did the researchers find?

Physical and mental function, as well as mood and fatigue, seemed to return to normal within about 1 year. Participants with infection affecting their brain took slightly longer to recover, but they recovered to about the same extent as those with infection affecting their spinal cord.

What were the limitations of the study?

The researchers could not study 7 people who died soon after their infection, so the study's findings may be slightly optimistic. Also, the researchers did not have measures of participants' health before the infection, so they could not say that all participants returned to the previous level of health, just that they returned to a level of health that is normal for uninfected groups of people.

What are the implications of the study?

On average, people with West Nile virus infection return to normal health within about 1 year after their first infection.