MDs alerted to West Nile paralysis

Risk of polio-like symptoms higher than most realized: study

Thursday, July 10, 2003

Doctors across Canada are being warned to be on the alert for rapidly progressing paralysis as a symptom of West Nile virus infection.

As officials investigate Canada's first possible human case of the mosquito-borne illness this year, new research shows that the risk of polio-like symptoms in people infected with the disease is greater than doctors originally believed.

Half of West Nile virus patients admitted to a U.S. hospital last summer over a two-month period experienced severe muscle weakness or paralysis that developed rapidly, in many cases spreading to both arms and legs within three to eight days.

Nine of 23 patients studied had to be connected to a ventilator when their breathing muscles became paralysed.

Three of the patients died and one man was only recently discharged from a nursing home -- more than eight months after he was hospitalized.

"West Nile virus infection can cause significant disability," warns the study's lead author, Dr. Lara Jeha, of the Cleveland Clinic in Ohio. But many cases of West Nile virus are still being misdiagnosed.

The researchers say doctors need to be vigilant for a "fairly rapidly progressive motor paralysis" in patients who show up in emergency rooms this summer with fever and other symptoms of a serious viral infection.

"We need to educate emergency room doctors and family practitioners about the threat of this (West Nile infection) progressing," says neurologist Dr. Richard Lederman.

The study is published this week in the journal Neurology.

More than 4,000 people in the United States and Canada became ill last year after being infected with West Nile virus, including at least 400 in Canada. So far this year virus-infected birds have been found in Saskatchewan, Manitoba, Quebec and Ontario.

The first Alberta bird was recorded yesterday. The dead magpie was found near Camrose, southeast of Edmonton. A second has been sent for testing.

And Health Canada scientists may know as early as today whether they can rule out a suspected case of West Nile infection in a New Brunswick man. On Monday, health officials from the province announced that preliminary tests indicated a man in his 60s has the disease.

Meanwhile, the U.S. this week confirmed its first human case in a South Carolina man who reported being bitten by mosquitoes while fishing. He's recovering after being sent home from hospital last month.

Studies suggest that fewer than one per cent of people who are bitten by a West Nile-carrying mosquito get seriously ill. Of those, there is about a 10-per-cent fatality rate.

But doctors have only recently begun to appreciate just how serious the disease can be.

In the new study, researchers did a detailed analysis of patients who were admitted to the Cleveland Clinic with West Nile virus infection between August and September 2002. The 23 patients ranged in age from 12 to 85, although most were elderly. A full 74 per cent were men, although it's not clear why there was such a significant gender difference.

All of the patients had a fever. Other major symptoms included back pain, stomach complaints and a rash. Three-quarters experienced some form of "altered mental status," meaning they became confused, agitated or sleepy. Some suffered tremors or seizures.

Half the patients developed symptoms of meningitis -- inflammation of the meninges, the covering of the brain -- or encephalitis, inflammation of the brain, in addition to extreme muscle weakness or paralysis, usually on one side of the body. In some patients, the paralysis spread to the muscles in their eyes, jaws and face.

The infection "generally doesn't paralyse within hours, but these people can progress quite rapidly from normal strength to profound weakness in just three days," says Dr. Lederman, a staff neurologist at the Cleveland Clinic.

He said the clinical picture "reminded us of polio," and while other studies have suggested only a minority of patients develop muscle weakness or paralysis, "in our cases it was half." He cautioned that the study sample was small.

© Copyright 2003 The Ottawa Citizen