By February 2022, the committee concluded there was no mystery neurological syndrome and found "potential alternative diagnoses" for most of the patients, including Alzheimer's disease, Lewy body dementia, and post-concussion syndrome.

In October 2023, federal microbiologist Michael Coulthart, who is the head of Canada's Creutzfeldt-Jakob disease surveillance system and was part of the initial investigation, said in an internal email obtained by CBC News that he was "essentially cut off" from working on the file for reasons he could "only discern to be political," but he believes there is "something real going on" in New Brunswick.

Election promise

On Aug. 30, Holt, then Opposition leader, said New Brunswickers suffering from unexplained symptoms and the doctors trying to help them had "been ignored" by the Higgs government "for far too long."

"New Brunswickers deserve answers," she said in a statement at the time.

Her new Liberal government has released mandate letters she wrote to each cabinet minister, outlining their key priorities and responsibilities. Health Minister Dr. John Dornan's long list of commitments includes "a scientific review into the mystery brain disease." No timeline is indicated.

Holt could not immediately say how long it will take to get the money from Ottawa. But now that the federal commitment is secured, she can direct Public Health New Brunswick to begin to plan the study, she said.

"We need to get the right team together to look through the data and the environments and to run a complete and thorough scientific investigation until we can answer the question with some confidence and reliability that this is what's making New Brunswickers sick."

People can expect to see progress as early as January, Holt said.

The premier said she doesn't know why the former government declined federal assistance but did say she thinks it "maybe was the wrong [decision] to make and absolutely needs to be revisited," particularly now that "more and more" cases have come forward, including ones in other provinces.

Growth unprecedented, neurologist claims

Marrero, who originally identified what he believes to be a new disease to health officials, said he has now notified Public Health of 366 patients from New Brunswick and six other provinces, including Nova Scotia, P.E.I., Newfoundland, Ontario, Quebec and Alberta, through a standard one-page form.

Of those patients, 120 are under age 45, said Marrero.

Forty-two people have died, he said.

An additional 101 cases are under investigation, and he believes there are "hundreds more."

Moncton neurologist Dr. Alier Marrero says he feels the 'distress and the sense of urgency' of his patients, who now number in the hundreds. (Virginia Smart/CBC)

Department of Health spokesperson Sean Hatchard did not immediately respond to a request to verify Marrero's numbers, but did confirm Marrero has submitted "initial notification forms" for people whose primary residence is outside New Brunswick.

Under the Public Health Act, medical professionals must report notifiable diseases, including certain "unusual illnesses" to the department by filling out a one-page form.

"In addition, to be able to better assess this particular situation, the department created an enhanced surveillance form to collect additional information on each submitted notification," said Hatchard.

Public Health has received "only 29 completed notifications" from Marrero since May 2023, he said.

Marrero contends the second form, created last year, requires "extensive" information, such as all the doctors a patient has seen and when, all diagnostic test results, such as CT and MRI reports, and all biomonitoring, such as blood or urine tests related to pesticide, herbicide or heavy metals exposure. 

The forms take "an immense amount of time," he said.

Patients and families hopeful

New Brunswick patients and their families are hopeful Holt will "do the right thing" and not "succumb to any kind of pressure not to — if there would be any," said patient representative Stacie Quigley Cormier of Dalhousie Junction.

"Politics has no business in medicine," said Quigley Cormier, whose stepdaughter Gabrielle Cormier is one of the youngest patients seeking answers to what's causing her mind and body to deteriorate.

The 23-year-old, who hoped to become a pathologist, had to drop out of university in 2020 because of her symptoms. She suffers from extreme fatigue, struggles with concentration and memory, has lost some peripheral vision, depends on a cane or wheelchair and requires home support.

                                            Gabrielle Cormier felt her health take a turn for the worse during her first term at university in September 2019. By mid-April 2021, she was included in the original cluster of 48 patients. (Submitted by Stacie Quigley Cormier)

Last month, Quigley Cormier sent a letter signed by 48 patients and family members to Dr. Yves Léger, the acting chief medical officer of health, saying they do not have confidence in his leadership. She cited "inaction and lack of urgency" in determining the root causes and interim treatments.

Léger has only served as the province's top doctor since last December, when Dr. Jennifer Russell resigned. He was previously the acting deputy chief.

The letter, copied to Holt, Theresa Tam, Canada's chief public health officer, and federal Health Minister Mark Holland, describes the provincial investigation as an "abject failure" and requested that the Public Health Agency of Canada take over as the scientific lead.

                 Gabrielle Cormier and stepmother Stacie Quigley Cormier, pictured at a news conference in March 2023, hope to see a patient advocate at the table when the investigation is launched. (Submitted by Stacie Quigley Cormier)

It also expresses support for Marrero and alleges his concerns and requests for help have largely been "sidelined," based on internal correspondence obtained through a right to information request.

While it's still too soon to say what that team will look like, the initial investigation in 2021 involved federal and provincial experts in food safety, environmental health, and infections that travel between animals and humans, exploring issues such as heavy metals and the neurotoxin BMAA, which is produced by blue-green algae.

Marrero had warned that some patients' blood work showed elevated levels for compounds found in herbicides, such as glyphosate, and said more testing should be done to rule out environmental toxins, including BMAA.

If the environment is the cause, that means exposure, illness and death can be prevented, stressed Quigley Cormier. Scientists must be given the opportunity to "rule it in or rule it out."

The focus needs to return to patients, she said, adding she hopes a patient advocate and Marrero will be included in the investigative process.

Holt confident in Public Health team

Holt said she can appreciate the frustration and cynicism of New Brunswick patients about possible political interference at Public Health but contends the issue requires "all hands on deck" — both provincial and federal.

 Some patients and their families have said they have no confidence in Dr. Yves Léger, acting chief medical officer of health, to lead the investigation and want the Public Health Agency of Canada to take over. (Submitted by Dr. Yves Léger)

Asked whether she stands by Léger, Holt said she trusts the civil service and is confident the acting chief medical officer of health and his team will follow the directive to "tackle this and to put urgency and resources behind it to get New Brunswickers the answers that they need."

In an emailed statement, Léger did not respond directly to the criticism from Quigley Cormier.

"At this time, we look forward to working with the new government and bringing them up to speed on this important file," he said.

The Office of the Chief Medical Officer of Health has not formally received Quigley Cormier's letter, according to the Department of Health spokesperson.

Public Health would welcome support of federal agency

Once Public Health receives all the completed notifications from Marrero, the epidemiology and surveillance branch "will initiate an analysis plan, which was developed with the support of [Public Health Agency of Canada]" and determine next steps, said Hatchard in an emailed statement.

He said Public Health "would certainly welcome the support" of the federal agency in reviewing the findings of the analysis and "providing them with any advice or suggestion on its interpretation, or thoughts on further work that could be considered."

The agency is available to support provinces and territories upon their request, said spokesperson Anna Maddison, but provinces and territories would take the lead.

She said no requests have been received yet and no other provinces or territories have contacted the agency regarding similar cases of illness.