Saturday, June 19, 2004

Researchers track West Nile survivors

Jackie Jadrnak The Albuquerque Journal

To most people, a mosquito bite is little more than an annoyance: a buzz, prick and itch. With the advent of West Nile virus, though, that annoyance can lead to serious illness for a small percentage of people bitten.

Last year, 209 New Mexicans got the virus; 74 developed severe disease; and four died. That was the first year the virus infected people in this state.

Now researchers are following patients from last year to see how many still are having symptoms from their illness.

One of the unexpected things about West Nile virus in this country is that, in a small group of people, it is behaving almost like polio, according to Dr. Larry Davis, chief of neurology services at the New Mexico Veterans Affairs Health Care System.

"They get an infection of the spinal cord as well as the brain," he said. "They get severe weakness and atrophy of the muscles as if they had polio. We're still not sure why."

"There's a dearth of data on what happens after West Nile," said Dr. Diane Goade, associate professor and infectious disease specialist at the University of New Mexico. "Small amounts of data suggest that it may be a long-term or even permanent disease."

To find out more, she and Davis, with help from colleagues at their institutions and the state Department of Health, are trying to follow up on every New Mexican who got West Nile virus last year.

They're already more than halfway through the list. Many people simply answer a telephone questionnaire that assesses whether or not they're having continuing symptoms and, if so, what they are.

People with serious continuing problems then will be asked to undergo a series of studies: a complete neurological exam, possible brain imaging studies, and tests to see how good their memory and thinking are.

Some even may be asked to undergo a lumbar puncture to get a sample of their spinal fluid. That's because doctors are trying to figure out if the virus remains active in people with lingering symptoms, Davis said.

That spinal fluid wouldn't give the final answer, though, since it could be clear of the virus while it still may be present in the brain. No one is interested in performing an invasive brain biopsy, though, on relatively healthy people.

Right now, no one is sure if the symptoms remain because the virus is still in the person's system, or if it simply causes initial damage that lingers long after the virus itself is gone, he said.

Since no one has found progressive disease — symptoms that keep getting worse and result from growing damage — Davis said he would be surprised if anyone found still-active virus in people.

There are some indications that even people who simply had a fever from the virus, but not the more serious meningitis or encephalitis, also are experiencing long-term problems as a result, according to Paul Ettestad, public health veterinarian. "The fever may not be as mild (an illness) as we say it is," he said.

West Nile virus has been full of surprises in this country. In New Mexico, some people didn't expect very many cases to show up, since this arid state doesn't have a lot of mosquitoes.

"I predicted we would see 10 cases last year — nowhere near the 200-plus," Davis said.

And the disease itself wasn't expected to cause as many severe illnesses as it did after it was first identified in this country in 1999, he said. The experience in North Africa and

the Middle East, where the disease has existed for years, didn't show many lingering symptoms from the infection, he said.

The difference could be that many children may get infected in those countries, making them immune by the time they get older, Davis said. The disease tends to be more severe in people 50 and older.

"Or there may be other factors, such as different mosquitoes," he added.

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