The disease stems from the same virus that causes chicken pox - herpes zoster - which lies dormant in the body and sometimes becomes active again. Anyone who has had chicken pox can develop shingles, but the condition typically erupts later in life or among those with a weakened immune system.
The first sign of shingles is often an itching, tingling or burning feeling, followed by a rash of fluid-filled blisters. Although shingles can occur anywhere on the body, it often appears as a single band that wraps around either the left or the right side of the torso.
Anxiety and embarrassment over the eye-catching lesions on his face prompted Barsky, a busy lawyer in Mississauga, Ont., west of Toronto, to call in sick for the first time in decades.
"You can't go out in the street the first couple of days," he said.
But that paled in comparison to the excruciating nerve pain brought on by the virus - and the risk of losing sight in his left eye due to inflammation caused by the infection.
A dull, steady ache still lingers more than a year after the sores faded. And though the appearance of his face is back to normal, Barsky said the discomfort makes him feel "disfigured."
"Luckily, I have not had any eye damage. But I have soreness that goes from below my eye to my cheek, around my eye socket into my forehead and along the side of my nose. That has lasted for 15 months," he said.
"My eye feels like I've got an eyelash in my eye, I constantly feel that."
Of the legions of Canadians who will get shingles in their lifetime - studies suggest that could be up to one in every three people in the population - a number will endure post-herpetic neuralgia, a type of pain that lasts for weeks, months or even years after the skin has healed.
"Although generally it's not a life-threatening disease, it's incredibly debilitating," said Dr. Allison McGeer, an infectious disease specialist at Toronto's Mount Sinai Hospital.
"It's the degree of pain that frequently means that people can't work, sometimes means you can't wear clothes because just any touch on top of it is so painful," the microbiologist said.
"And because it's pain from the nerves, it's very, very hard to treat - you can kind of dull it in a variety of ways, but it's very hard for people to get relief from this continuous and very severe pain."
That distress is often compounded by a lack of sympathy from others once the visible signs of illness are gone, said Lynn Cooper, president of the Canadian Pain Coalition, a group devoted to improving the treatment of chronic pain.
"Most people wouldn't be able to comprehend that someone who has had shingles and who got over it and you don't see the marks anymore ... they wouldn't be able to comprehend why that individual would now complain about pain," she said.
Over time, the stress of dealing with such severe discomfort, heightened by the inability to get a good night's sleep, can lead to depression, Cooper said.
Experts say there is only one surefire way to stave off long-term pain caused by shingles: avoiding the disease altogether.
Anti-viral medication can help soothe the rash if administered within 72 hours of the first blister, but few people recognize the symptoms quickly enough to get a dose in time, said McGeer.
And the treatment does little to prevent lasting pain, "which is what you really care about," she said.
Two vaccines help keep shingles at bay, though only one targets the disease directly.
The chicken pox vaccine, routinely given to children in Canada, simultaneously protects against shingles by keeping the virus from taking root in the body.
"If you don't get the first infection with chicken pox, then you can't get shingles," McGeer said.
The shingles vaccine, on the other hand, is aimed at adults who have already had chicken pox. It contains a "much higher dose" of the virus in order to jump-start the immune system and beef up its defences, she said.
The vaccine is recommended for anyone over age 60. But because the drug, which sells to doctors and pharmacists for $150 per dose, isn't covered by provincial and territorial drug plans, consumers must pay for the shot from their own pockets.
The product had been in short supply, but a spokeswoman for manufacturer Merck Canada said full shipments have now resumed.
Barsky said "sheer ignorance" about the disease made him put off vaccination until it was too late.
"I was uninformed as to ... how bad it could be," he said.
In a strange twist, there is growing speculation that widespread use of the chicken pox vaccine could make some adults more vulnerable to shingles in the future because they will be less exposed to the virus in children.
"It's then expected - it's not proven - it's then expected that instead of getting shingles when they are 70, 75, 80, they may get shingles when they're 60, 65, 70," McGeer said.