TORONTO - Sylvia Gordon is plagued by painful muscles and joints, shortness of breath and a lack of energy, all unwanted gifts of a disease that keeps on giving.

The nurse was among the first wave of health-care workers and patients stricken by SARS in early 2003, but the five-month outbreak that killed 800 people worldwide, including 44 in the Toronto area, is far from done among those who survived the disease.

Patients who were infected but came through the epidemic are learning that severe acute respiratory syndrome can leave lingering physical and psychological effects, which not only don't resolve over time but can actually get worse.

"I have not been able to return back to the front line at all," said Gordon, 57, of her 22-year nursing career. "It's very difficult because one day you're feeling really well and the next day you're not."

SARS, initially considered a severely acute illness that would resolve like other pneumonias, has turned out to be a chronic disease with symptoms that researchers speculate could persist for life.

"It certainly is something that's unfolding that we're learning about," said Dr. Paula Gardner, a psychologist at St. John's Rehab Hospital in Toronto, who is studying the long-term effects of SARS. "We couldn't know this before because it's a completely new disease.

"And so we're sort of watching and waiting and measuring and trying to see what's going to happen."

Gardner and a team of researchers at St. John's Rehab have been following 40 people who contracted SARS in 2003, most of them health-care workers.

Their study, presented last month at an International Congress of Behavioural Medicine meeting in Washington, used questionnaires to assess the physical and psychological health of participants in 2004 and again in 2007.

"So what we could do was get a snapshot at one year and at four years (post-SARS) and then we could compare across time," Gardner said. "At both time frames, the ratings of their general health and mental health and vitality were all reduced from the norm."

What surprised the researchers was that patients not only weren't getting better as time went on -- many seemed to be getting significantly worse.

The study found that in 2007, almost 88 per cent of patients were below average for measures of general health, compared with about 49 per cent three years earlier.

Participants, who had an average age of 50, reported shortness of breath, muscle and joint pain, numbness and tingling in the hands and feet, and fatigue.

"And it's not the kind of fatigue like 'I just feel kind of tired today.' It's the kind of fatigue where you do something for an hour, you have to rest. You have no choice," Gardner said.

Patients, all of whom had been taking part in a SARS-rehabilitation program at St. John's, also tended to have increased symptoms of depression, anxiety and post-traumatic stress.

In fact, about 30 per cent of study participants showed distinct signs of post-traumatic stress disorder, or PTSD, even four years after contracting SARS.

PTSD, a condition increasingly being diagnosed in war veterans, can cause nightmares and flashbacks and lead the person to avoid talking about the traumatic event or returning to the place where it occurred. Many exhibit signs of hyperarousal, including irritability, jumpiness and being constantly alert for danger.

"I guess what was surprising to us is that the number is so high, even after such a long time," said Gardner. But she stressed that for many with SARS, having the disease was a highly traumatic event.

"People came near death in most cases. It was a life-threatening illness," she said. "You were isolated, so you were isolated away from family and loved ones in a room, some people without a window. And that went on for days and days."

"You didn't know if you were going to live or die and see your family before that happened."

Gordon was a coronary intensive care nurse at Scarborough Grace Hospital when she got SARS after caring for a patient admitted with respiratory distress in March 2003. Hospital staff didn't know the man had SARS, a new disease that had just begun striking people in China.

She was among 14 health-care workers from Scarborough Grace placed into isolation for two weeks at another Toronto hospital, where her husband and daughter were not allowed to visit. Some of her colleagues or their family members died, as did the man who had infected her.

"It was just overwhelming," said Gordon, who believes she was among those SARS patients who developed PTSD.

"Mentally, I'm still very cautious about diseases, where I go and hospital settings," she said. "So it all inter-relates, the physical and the psychological. It's hard to differentiate when one is at work or if it's the other at work."

SARS patients also suffered from stigmatization because of people's fear that any contact would mean certain infection and possibly death, said Gardner, exacerbating the sense of isolation.

Gordon, who experienced depression and anxiety, recalls withdrawing from people -- in part because of the stigma that seemed to linger long after she was no longer contagious.

"I remember going into my dentist four years post-SARS and she just panicked when I told her I had SARS," she said. "She just freaked right out."

While she has worked through a lot of her emotional issues -- among them anger at how health-care workers were kept in the dark about the new infectious threat and put unwittingly in harm's way -- Gordon said it is the physical residues of SARS that most concern her now.

"I've come to terms with a lot of the issues that surrounded the whole thing," she said. "But physically, I think I have to contend with this forever."