New Brunswick

Doctor who sounded alarm on mystery disease sidelined from province's investigation

Back in April, more than a month after New Brunswick public health officials first sounded the alarm about “a distinct atypical neurological syndrome,” Health Minister Dorothy Shephard pointed to Moncton neurologist Dr. Alier Marrero as the person who was going to get to the bottom of what was going on.

Change in Dr. Alier Marrero's role in investigation comes as officials question validity of mystery illness

Moncton neurologist Dr. Alier Marrero, seen here in a file photo, previously played a key role in the province's quest to get to the bottom of a mystery neurological illness affecting a cluster of his patients. (Tori Weldon/CBC file photo)

Back in April, more than a month after New Brunswick public health officials first sounded the alarm about "a distinct atypical neurological syndrome," Health Minister Dorothy Shephard pointed to a Moncton neurologist as the person who was going to get to the bottom of what was going on.

It was Dr. Alier Marrero, the man who'd treated most of the 48 patients who make up the cluster and, after initially fearing they had a rare and fatal brain disease, referred them to the federal Creutzfeldt-Jakob Disease Surveillance System. 

The doctor described how, dating back to 2013, he began detecting unusually young patients with progressive neurological symptoms in the Moncton and Acadian Peninsula areas.

Now, months later, Public Health is questioning the validity of the idea of an unknown cluster of neurological illness.

Officials presented a report Wednesday that said they couldn't find any significant behaviour, food or environmental risk factors linked to the cluster of patients.

A second investigation, led by a group Shephard has described as the oversight committee and made up primarily of other neurologists from across New Brunswick, will deliver a second report early next year after doing clinical reviews for all 48 patients, most of whom were treated by Marrero.

But Marrero doesn't seem to be part of that process.

Government officials seemed to distance him from the investigation on Wednesday, and at times, questioned his work, even if not referring to him directly by name.

"We have also had concerns about the [Creutzfeldt-Jakob Disease Surveillance System's] over-reliance on the validity of information received from individual physicians," says a letter Shephard sent to federal Health Minister Jean-Yves Duclos on Wednesday, without mentioning Marrero by name.

But both Shephard's own comments and records obtained by CBC News through access to information show Marrero played a key role in its early investigation into the syndrome, before his role was changed in recent months.

Doctor's role changed over previous months

In April, Shephard was asked what was being done to figure out what the cluster of illness is and who was on the team tasked with doing it.

"The steering committee is led by Dr. Marrero out of Moncton," Shephard told Information Morning Fredericton's Political Panel in April. 

Even in late May, after the province created an oversight committee, made up mostly of other neurologists from New Brunswick to provide a second opinion of Marrero's work, Shephard made it sound as though Marrero would continue to play a key role.

"We have put in place an oversight committee to assist Dr. Marrero with this process and to ensure that we're covering all of our bases and all of the information that [patients] give, we want to make sure we put expert eyes on it to do the very best," Shephard said on May 27.

"We need for the committee and Dr. Marrero to do their work, to start with their questionnaire, which is lengthy, and will actually give them a lot of information to examine to put them on a path," Shephard said on June 3.

But by Wednesday, Shephard's tune had changed.

"Dr. Marrero was not the lead on this investigation," Shephard told reporters. "Public Health was the lead on this investigation. And I think you can appreciate that when an investigation into a potential cluster of neurological syndrome is taking place, it should be from an unbiased perspective.

"So that's why Public Health not only put in place the epidemiological enhanced survey, but also the oversight committee with six neurologists not connected with the patients that were being seen, so that there could be an unbiased perspective injected into all of the cases."

When asked if Marrero made a mistake in his diagnosis, Dr. Natalie Banville, co-chair of the government's committee and vice-president of medical affairs at Vitalité Health Network, where Marrero is employed, didn't answer directly.

Dr. Natalie Banville is co-chair of the government's mystery illness oversight committee and vice-president of medical affairs at Vitalité Health Network. (Government of New Brunswick)

"With the evidence that was revealed today, we will need to sit down with this doctor to review the files and discuss this with him," Banville said.

"We cannot make any comments before discussing this with him." 

Marrero a key part of early meetings about cluster, records show

Reached Wednesday evening by Radio-Canada, Marrero said no one from the government shared its epidemiological report with him prior to its release earlier that day.

He was also surprised to find out the findings of Ottawa neuropathologist Dr. Gerard Jansen, who found eight deceased members of the cluster died from known illnesses such as cancer and Alzheimer's disease, was posted online by the Canadian Association of Neuropathologists.

Marrero, who said he missed the news conference while he was treating patients, seemed surprised to hear some of the government's findings. But he stood behind his work.

"This is not a theory that I invented," he said in French to Radio-Canada.

Marrero said he wasn't alone in coming up with his findings, referencing dozens of meetings and field epidemiologists who worked for weeks "to come up with the conclusion that there is a pattern here and that pattern is new."

"This case development, I participated in it, but it was done with the rigour of the analysis of experts who participated in it," Marrero said in French.

Records obtained by CBC News through access to information show Marrero played a key role in several meetings Public Health held about the mystery disease, dating back to February 2021.

He was tapped to make presentations to subject matter experts in the Department of Environment and Local Government, as well as the Department of Agriculture, Aquaculture and Fisheries.

The meetings organized by Public Health appeared to stop in late April, though according to Shephard's comments at the time, Marrero was still involved with the investigation at that point.

By Wednesday, it appeared Marrero has now been completely severed from the investigation.

Marrero, pictured here at the Mind Clinic at the Moncton Hospital, is not part of a committee set up by the Department of Health to investigate a cluster of patients with an unknown neurological illness. Marrero treats many of these patients at the Mind Clinic. (Horizon Health Network)

The government's report repeatedly referred to a single neurologist who referred 46 of 48 patients to the Creutzfeldt-Jakob Disease Surveillance System who later became part of the cluster.

Shephard also said the government's investigation had found "gaps in the reporting process that allowed this situation to escalate, often without oversight." 

When asked why public health officials were distancing themselves from Marrero after officials had been working with him for months, Shephard said the investigation needed to be "bigger than just one neurologist."

"It's not about trying to put anyone's at arm's length, but an independent, unbiased oversight committee needs to do their work so we can validate the find or see if there is another diagnosis."

'We don't need to go into panic or fear'

Shephard also pointed the finger at the federal Public Health Agency of Canada on Wednesday, though that criticism didn't single out any specific doctor.

She told reporters that New Brunswick public health officials waited months to gain access to autopsy results for members of the cluster and wrote a letter to the federal health minister to detail those challenges.

"I highlighted the difficulties we faced during this investigation and that no jurisdiction should ever go through this type of situation," Shephard said on Wednesday.

The Public Health Agency of Canada hasn't yet responded to an interview request to respond to Shephard's comments.

For Marrero's part, he would still like to see national experts, "who have been doing this for a long time," involved in the investigation.

"We don't need to go into panic or fear," said Marrero, who is still treating patients in the cluster.

"I think our best response should be, take a step back, go back to what we need to do. Care for our patients. Analyze this with our teams, both the national groups and the local clinical and scientific groups."

If you have a tip about this story, you can reach our journalists at

The Fifth Estate has been looking into the cases of mysterious illness in New Brunswick and the provincial government's reaction.

Their investigation will air next week, Thursday, Nov. 4, at 9 p.m./9:30 p.m. in Newfoundland and Labrador.


Karissa Donkin is a journalist in CBC's Atlantic investigative unit. Do you have a story you want us to investigate? Send your tips to

With files from Nicolas Steinbach of Radio-Canada and Maeve McFadden


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