Measles outbreaks spark concern over rare 'horrific' neurological disorder

CBC

12-04-2025

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Dr. Michelle Barton has been working at the heart of Ontario's measles outbreak for months, trying to contain the damage the highly-infectious disease can wreak on children hospitalized with the virus.
Barton heads up the pediatric infectious disease team at London Health Sciences Centre children's hospital in the province's southwest, the region with the highest rate of the illness.
"We offer the best treatment that we can under the circumstances," Barton said. "If the child proceeds to deterioration, that is difficult to watch because you know that you probably wouldn't be here if they had had vaccines."
Barton and other doctors are worried that outbreaks in Canada will follow the same trajectory as those in the U.S., where two unvaccinated children have died of measles. Pediatricians and immunologists say they are also watching for extremely rare neurological conditions that can occur even years after children who've had measles recover from it.
As of Friday, provincial health authorities across the country had reported 914 cases of measles, surpassing the 751 infections for all of 2011. The total is the highest since measles was eradicated in Canada more than 25 years ago.
The bulk of the cases in the country have been reported in Ontario, with Public Health Ontario detailing 804 confirmed and probable cases of measles this year so far.
In March, the province's chief public health officer said the rise in measles cases in southwestern Ontario linked back to a travel-related case in New Brunswick last fall, which sparked what the Public Health Agency of Canada has called a multi-jurisdictional outbreak.
P.E.I.'s Chief Public Health Office said two adults who tested positive for measles on the island had travelled together to an area in Canada where outbreaks continue. On the Prairies, provincial figures show measles cases are climbing in Alberta.
Barton is particularly concerned about children with suppressed immune systems, such as those receiving chemotherapy. If they contract measles and "don't get to the hospital fast enough, we could end up losing patients."
Canadian doctors worry there will be deaths
In Alberta, every zone in the province now has measles. Dr. Cora Constantinescu, a pediatrician and infectious diseases specialist at Alberta Children's Hospital in Calgary, is watching the cases mount and spread, calling her worry about a death from measles "incredibly distressing."
"We're probably looking at the beginning of a significant measles outbreak," she said.
South of the border, two unvaccinated children with no underlying health conditions have died of measles in Texas, including an eight-year-old girl last week.
On Friday the U.S. Centers for Disease Control and Prevention reported 712 cases of measles so far this year in 25 jurisdictions, including Texas and New Mexico. Gaines County, Texas, the centre of the outbreak, measles counts on Friday rose to 355, up from the 328 reported on Tuesday, the Texas Department of State Health Services said.
The federal agency said 97 per cent of U.S. measles cases are individuals who are either unvaccinated or have an unknown vaccination status.
The reason measles is so dangerous is because it is so highly infectious, said Dr. Dele Davies, a Canadian professor of pediatrics and infectious diseases at the University of Nebraska Medical Center.
Measles usually starts with a cough, runny nose and red eyes, followed by spots inside the mouth and a rash that starts from the top of the head and moves down.
The measles virus causes a high fever, but it also suppresses the immune system.
"The lining of the airway gets affected and it becomes an ineffective barrier," Barton said. "In the face of this virus, which is very what we call immunosuppressive, you can end up with pneumonia." She noted that ear and other secondary infections are also common.
Davies says in children under five, about 10 per cent will get ear infections and many will develop diarrhea.
More serious complications include swelling of the brain or encephalitis in about one in 1,000 cases, which can lead to drowsiness, confusion and seizures that resolve, Barton and Davies said.
'Horrific' and rare complication
While they are extremely rare, long-term neurological problems can occur even after a young child has recovered from measles.
Barton says the measles virus itself stays at a low level in the brain and can wake up six to 10 years later as a devastating disorder called subacute sclerosing panencephalitis, or SSPE.
Immunologist Dawn Bowdish, a professor of medicine at McMaster University, says the measles virus has mutations that allow it to hide out from the immune system, then move from neuron to neuron where the parts of the brain required for cognition and movement can be damaged.
"It starts with challenges in learning or memory," Bowdish said. "They don't reach their full intellectual potential … something no parent wants for their child."
Those with SSPE can have seizures. Medical experts say that in almost all cases, the disorder progresses until the patient is in a vegetative state, and it eventually ends in death.
Davies estimates SSPE occurs in about one in 10,000 people with measles, but he notes that "statistics are irrelevant to that one mother whose child [has] now all of a sudden gotten this really horrific disease."
Vaccine very safe and highly effective, doctor says
Conversely, Davies says the measles vaccine is very safe and highly effective. "It's important not only for saving lives, but also for preventing chronic disease."
In Alberta, Constantinescu notes the province's electronic immunization record is accurate, but vaccination uptake drops as low as 50 per cent in some communities, meaning there are a lot of people unprotected from measles.
"This is a big deal disease," she said. "You do not want to have what people call natural immunity from measles because the risk of having measles itself is so significant."
Constantinescu suggested that what she called the silent majority of parents who have vaccinated their children should share why they did so on their social media accounts to help others feel confident to do the same and "ultimately protect our communities and stop these outbreaks."