In the four years since she first heard of West Nile virus, Cecilia Warren never imagined that it could trigger a paralyzing illness similar to polio.
That was before she watched her father, a vigorous Crofton retiree who went to sleep four weeks ago feeling vaguely ill, lose the ability to move his arms and legs or even breathe on his own.
"Talk about a completely random act," she said near Gerald Warren's room at Johns Hopkins Hospital, reflecting on how a single mosquito, buzzing around an average neighborhood, could do this to anyone - much less to a man who was never bothered by anything worse than a hernia.
"It has disabled an adult who was in excellent health," she said.
Though West Nile made its first appearance in the United States four summers ago, doctors are just coming to grips with the apparently rare, but devastating cases of West Nile paralysis that have cropped up across the country.
Dr. James Sejvar, an epidemiologist and West Nile researcher with the U.S. Centers for Disease Control, said he is aware of cases of paralysis over the past two summers but still has no idea how frequent they are.
"It really has not been looked at in a systematic fashion," he said.
As a first step, Sejvar is tracking every case of West Nile illness in Colorado, this year's hardest-hit state. By the time the first sustained frosts kill off this year's bumper crop of mosquitoes, he should have a good idea of the paralyzing illness' scope. The National Institutes of Health has also launched a study of muscle-weakening West Nile cases.
Experts agree that the paralytic disease has much in common with polio. Both are caused by a virus that damages motor neurons - cells in the spinal cord that power muscles. And both can cause localized or widespread paralysis, in some cases silencing the muscles that control breathing.
Dr. Daniel Hanley, a Johns Hopkins neurologist participating in the NIH study, said he hopes to learn why paralysis strikes some patients and not others, how likely patients are to regain muscle strength and how symptoms typically progress.
The study comes as the disease continues its westward march. It originally showed up in New Jersey and New York, spread along the East Coast and through the Midwest, and this year is doing its greatest damage in Colorado and the Plains states.
This year's tally is close to last year's total of 4,156 cases and promises to exceed that number once the season ends and all cases are counted. In Maryland, 23 cases have been recorded, including four fatalities.
Although four patients have been hospitalized at Hopkins this year with West Nile complications, Warren is the only one with a paralyzing illness - and the only such patient Hanley has seen since the disease surfaced in 1999.
Among the many puzzling things about the paralytic illness is that its victims are often young and healthy. In contrast, most patients who get the more common West Nile illness - marked by headache, fever, skin rash and swollen lymph nodes - are elderly or have weakened immune systems.
A vigorous life
At 62, Warren was healthy, alert and vigorous. He retired several years ago from a career in law and teaching but soon joined several retired neighborhood buddies in taking on newspaper routes. He rose long before the sun to bag and deliver the papers - early enough on rainy days to double-bag - and he gave doorstep service to customers who were old or infirm, Cecilia Warren said.
Warren, who shared his home with his wife, Marie, his daughter and three grandchildren, also ferried his father - a man in his 90s - to medical appointments, did grocery shopping and prepared after-school snacks.
"He had an amazing capacity to retain trivia," said Cecilia Warren, describing him as an inveterate reader and C-SPAN watcher who was the family answer man on history, politics or most any other subject.
He was having a typically enjoyable summer before he got sick. In August, he and his wife celebrated their 40th anniversary, and on Labor Day, he attended a cookout at a relative's house a block away.
On Tuesday, Sept. 2, he felt lightheaded and retired early. Within two days, he had developed a fever of 104 degrees and had bouts of nausea and vomiting.
That Friday morning, Cecilia Warren - a paramedic for Anne Arundel County's emergency management agency - couldn't rouse her father. She called an ambulance, which took him to Anne Arundel Medical Center. There, doctors revived him and ran a battery of tests.
"He was somewhat awake but was not really responding to questions or voices," she said. The day he was admitted, Warren lost the ability to move his arms or legs. Doctors placed him on a respirator when his chest and abdominal muscles could no longer power his lungs.
Fluid from a spinal tap tested positive for West Nile virus, though a second test was inconclusive. Yet doctors at Hopkins, where he was transferred three weeks ago, are certain he suffers from West Nile.