West Nile has traditionally only been considered a serious problem for the elderly and frail, and more of a nuisance illness for everyone else. But a surprising number of patients show the virus is more threatening than widely believed.
New research finds that even so-called mild cases of West Nile fever can impair people for weeks or months.
Colorado woman Patricia Heller, a keen skier and a competitive cyclist, when she collapsed in the street after a daylong bike ride,shrugged off the weakness as cramps.But by the following morning Heller's left leg was completely paralyzed.
Heller had contracted West Nile virus from a mosquito bite she doesn't even remember and needed months of grueling therapy in order to walk again and now almost two years later, still isn't fully recovered.
Dr. Henry Masur of the National Institutes of Health, is concerned that as the nation gears up for a seventh season of the mosquito-borne virus West Nile is fading a little bit from the public consciousness. He says there are more cases of paralysis from West Nile than there were in many years of polio.
West Nile virus was present for decades, from the tip of Africa up to Europe and throughout Asia, before it appeared in New York City in 1999 and began an inexorable march across this country. Since then, the Centers for Disease Control and Prevention (CDC) have counted more than 16,600 human cases and 654 deaths.
Although severe illness is still rare, considering that 80 percent of people infected never show symptoms, last year, about a third of the West Nile cases reported to CDC had neurologic complications like meningitis or encephalitis. Those are most common in older adults.
Other patients like Heller, come down with West Nile's most perplexing complication, polio-like paralysis or severe muscle weakness that often strikes healthy people in their 30s, 40s and 50s. They may show no other symptoms before a limb suddenly quits working. Sometimes, the paralysis leads to respiratory failure.
There are no good counts of this particular West Nile complication, and some doctors believe it's frequently mistaken for a stroke or other paralyzing ailment.
Dr. Jim Sejvar from the CDC, in a study to be published in July, estimates that 10 percent of people who develop the most severe West Nile disease may have some degree of the polio-like complication, and many don't recover muscle function.
The less serious version of the illness, West Nile fever, is proving to be harder to kick than doctors initially thought, and the CDC has largely abandoned its earlier characterization as a "mild disease."
A Chicago health department study last autumn found that West Nile fever was severe enough to keep half of sufferers out of school or work for 10 days, fatigue lasted a month, and the average time to get back to normal was an appalling 60 days.