About 130,000 Canadians are diagnosed with shingles each year, according to Immunize Canada, and the rate is slowly climbing.
Roughly one in three Canadians will get shingles during their lifetime, according to Dr. Shelly McNeil, chair of Immunize Canada and head of the infectious disease division at the Nova Scotia Health Authority.
A 2016 study looking at British Columbia found that the rate of shingles in that province increased from 3.2 cases per 1,000 people in 1997 to 4.5 in 2012. Researchers aren’t sure why it’s becoming more common, though they have theories.
Shingles is a reactivation of the chicken pox virus, varicella zoster, later in life. People might catch chickenpox as a child, but although the pox disappear, the virus doesn’t really go away, said McNeil.
“Once that rash resolves, the virus, which is called varicella zoster virus, travels up the nerve roots and lives in the nerves around the spine. It lives latently, meaning it’s there and it’s active, but it isn’t causing any problem most of the time.”
As people get older, their immune system is less able to control the virus, so it sometimes reappears in a new form: shingles.
WATCH: Pharmacist Kelly Kizlyk with what to know about shingles, the warning signs and treatment options.
It’s a blistering red rash, that is linear – appearing in a line – and only on one half of the body. It typically resolves in one to four weeks, said McNeil, and can be painful, sometimes even days before the rash appears.
As people age, they’re more likely to get shingles and they’re also more likely to get potential complications, notably postherpetic neuralgia. “That is a nerve type pain that can persist in the area where the rash was for months or even years after the rash resolves,” she said. It’s difficult to treat and most pain medications don’t have much effect.
Among people of all ages, about 15 per cent of shingles cases result in postherpetic neuralgia. But about half of people who get shingles past the age of 70 will develop this complication, she said.
Why it’s becoming more common
There are a number of theories as to why shingles is becoming more common, said McNeil. “Generally, we are seeing increased rates of shingles in most jurisdictions, including in Canada. It’s likely due to many factors.”
One is simply that the population is getting older. Shingles is more common in older people, and as baby boomers age into a more high-risk demographic, it makes sense that overall numbers may go up, she said.
WATCH: According to medical professionals, 1 in 3 Canadians will contact the shingles virus. The infection can leave some people with unbearable pain that lasts for years.
Another possibility – somewhat paradoxically – is vaccination. “We know that as we immunize children, we have less and less chickenpox in the community,” said McNeil. So one theory is that parents used to get re-exposed when their kids caught chickenpox, and again as their grandchildren did, which gave them a “boost” in their immunity.
With fewer kids catching chickenpox since the vaccine was introduced in Canada in roughly 2000, adults aren’t having their immunity boosted so may be less able to keep the latent virus suppressed later in life. And so, they’re more likely to develop shingles.
Or so the theory goes. The U.S. Centers for Disease Control says on their website that they have studied this possibility and found that the rate of shingles was already going up before the chickenpox vaccine was introduced, and the rate didn’t go up faster after. The B.C. study also didn’t find a link between the vaccination program and the increased rate of shingles.
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Younger people are also getting shingles more often than they used to, something that McNeil thinks may be linked to the increased use of immune suppressant medications in young adults to fight conditions like rheumatoid arthritis or psoriasis.
Whatever the cause of shingles’ prevalence, adults are advised to get vaccinated against it.
“The vaccine for shingles is recommended for everyone in Canada over the age of 60,” said McNeil. In her own practice, she recommends that everyone over 50 consider the vaccine. Importantly, by vaccinating against shingles, you can also lessen your chances of developing painful complications.
She suggests people talk to their doctors about what vaccine is appropriate for them.