Doctors warn of 'frightening' measles complication that can strike a decade after initial infection
Virus can hide in brain and cause debilitating neurological condition 7 to 11 years later
As Alberta's measles case counts soar, doctors and scientists are warning parents about the long-term and lesser-known complications of measles.
And they can be deadly.
As of midday Wednesday Alberta had reported a total of 749 cases since the outbreaks began in March.
What many parents may not realize is that a rare and debilitating neurological condition, called subacute sclerosing panencephalitis (SSPE) can develop long after a child recovers from measles.
"It just frightens the heck out of me," said Dr. Sam Wong, an Edmonton-based pediatrician and president of the section of pediatrics with the Alberta Medical Association.
"Thankfully it doesn't happen very often but, when it does, it's devastating."
Most people can clear the measles virus once their infection is over.
But in some very young children, or people who are immune-suppressed, the virus hides out in brain cells and develops mutations that allow it to stay invisible to the immune system, according to Dawn Bowdish, a professor of immunology at McMaster University.
Brain inflammation
It can eventually flare up, causing brain inflammation, causing children or young adults to lose the ability to move and speak.
"It starts destroying the cells of the brain — there's no treatment, there's no way to repair a broken brain — and so eventually they can end up in a coma and then they will die of it," said Bowdish.
According to the Public Health Agency of Canada, SSPE occurs in between four and 11 out of every 100,000 measles cases.
Health officials say it strikes between seven and 11 years after an initial infection and the highest rates are among children who contract measles before the age of two.
"One of the reasons we're so universally stating that people need to be vaccinated is because some of these long-term effects are just so grim," said Bowdish.
Alberta's routine childhood immunization schedule recommends babies receive two doses of measles vaccine, with the first administered at 12 months and the second at 18 months.
The province is offering an extra, and early, dose of the measles vaccine to babies as young as six months old who are living in the south, central and north health zones, where the current outbreaks are most intense.
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As the lead medical officer of health for Alberta Health Services in the South Zone, Dr. Vivien Suttorp worries about young babies whose mothers are unvaccinated.
Typically, antibodies are passed along to the fetus during the third trimester, which protect them during their first few months of life, she said. But if a mom isn't immunized, the baby won't have that early protection.
"They're extremely vulnerable to getting measles after birth ... and of the complications," she said, pointing to SSPE.
"That's very concerning. And there is no treatment for that."
According to Alberta Health, SSPE declined with the widespread adoption of measles immunization decades ago.
Three cases of SSPE were reported in Alberta in 1984, followed by one case in 1986, one in 1990 and one in 1992.
No cases were reported from 1993 to 2013.
In 2014, there was one more case reported in a woman who was born outside of Canada with an unknown history of measles immunization.
Immune memory impacts
In recent years, measles vaccination rates in Alberta have declined, and experts say that has paved the way for surging outbreaks.
"Another curious complication [of measles infection] is immune amnesia," said Suttorp.
Measles can wipe out a person's immune memory, she said, and make people more susceptible to other infections for months and even years.
"So not only when someone has measles are they at higher risk for an infection like a bacterial pneumonia … but this also happens up to two to three years later," said Suttorp.
"There is a memory loss of viruses and bacteria that someone has been exposed to before and mounted antibodies to."
Bowdish said this this longer-term immune system complication happens because measles infects and kills a specific type of immune cells.
"We know that people who've had measles tend to need more doctors appointments, more antibiotics and they're more susceptible to other infections for months to years to follow because measles destroys the very immune cells that we use to protect ourselves," she said.
According to Bowdish, more severe initial infections trigger the loss of more immune cells and make the long-term impacts worse.
She's particularly worried about infants under six months old,who are too young to be vaccinated.
"Those are some of the people who are the most likely to have these really rare and severe complications," said Bowdish.
"There is nothing we can do except vaccinate the people around them to protect those really, really young babies."
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These long-term complications are in addition to the risks that come during the initial infection, which include ear infections, pneumonia, brain swelling and death. Measles infections are fatal in roughly one to three out of every 1,000 cases, according to the Alberta government.
Provincial data shows most of this year's cases are among children (569 of the 749 cases this year are under the age of 18). And the vast majority of cases are among people who are unimmunized.
"Please vaccinate your child," said Wong.
"It's very concerning from my point of view that, as the numbers increase, the risk of these longer-term side effects will increase, because it's a numbers game."
Measles symptoms include:
- High fever.
- Cough.
- Runny nose.
- Red eyes.
- Blotchy, red rash that appears three to seven days after the fever starts. In darker skin colours, it may appear purple or darker than surrounding skin.
Alberta Health provides detailed information on measles case counts, symptoms and free immunizations here.
A list of possible exposure alerts can be found here and a measles hotline is available for people with questions about symptoms, immunization records or to book an appointment: 1-844-944-3434.
A standing measles exposure advisory remains in effect for southern Alberta, due to widespread transmission in the region.
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