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While the province says there’s no mystery brain disease afflicting dozens, neurologist Alier Marrero is seeing a different pattern


When the New Brunswick government raised alarms about a potential cluster of 48 cases of a new and unusual brain disease in 2021, a driving force behind the concern was Alier Marrero, a neurologist in the province, who had seen and treated most of the patients.

Last year, when the government announced that a provincial public health investigation had concluded there was no mystery disease, and that the affected patients were likely suffering from known illnesses that had been misdiagnosed, Dr. Marrero offered no public response. He had been sidelined from the investigation, and repeatedly referred interview requests to the Vitalité Health Network, his employer.

But now he is once again saying publicly what he had previously maintained: that, despite the provincial findings, there could be a common unknown cause behind his patients’ illnesses – likely, he says, an environmental contaminant. And he says the number of his patients experiencing unexplained rapid neurodegeneration has increased, and now totals more than 200.

“I am advocating and ringing the bell and sounding the alarm and calling for help on behalf of my patients – as a physician and as a human being – on behalf of their families and their communities who desperately need answers,” he said in a recent interview.

In the more than a year since the New Brunswick government concluded there is no unknown neurological syndrome, it has not addressed Dr. Marrero’s claims about new cases in detail. The Globe and Mail is not able to verify whether his patients are actually suffering from an unknown disease. Interview requests to several federal experts who were initially consulted or involved in a national-provincial effort to study the illnesses have been referred to the Canadian Institutes for Health Research (CIHR), the Public Health Agency of Canada or New Brunswick health authorities, or have gone unanswered.

Last week, a group of four medical students and eight university professors – including Luc Tremblay, a professor in the department of chemistry and biochemistry at the Université de Moncton, and Matthew Betti, an assistant professor at Mount Allison University who was involved in the National COVID-19 Modelling Task Force – issued an open letter asking for a new public health investigation into the illnesses.

The letter’s author, James Paddle, a medical student entering his second year at Université de Sherbrooke’s Centre de formation médical du Nouveau-Brunswick, said he wrote it after a recent two-week placement with Dr. Marrero, during which he said he saw 20 to 30 patients with atypical symptoms.

Among the new patients Dr. Marrero has seen since the province concluded its investigation is Sarah Nesbitt, who is 40 and lives in Moncton. Previously fit and active, Ms. Nesbitt said she started feeling ill in the summer of 2020 and has progressively gotten worse. Her symptoms include kidney damage, and episodes of disorientation, stuttering, and vomiting. She said she once burned herself on an open flame because she couldn’t control her hand.

“Basically, this has taken my entire life,” she said.

Visits to the hospital and her family doctor yielded no answers, other than that whatever was plaguing her appeared to be neurological. Ms. Nesbitt’s doctor referred her to Dr. Marrero, whom she has been seeing since March, 2022.

Sarah Nesbitt in her backyard in Moncton. Ms. Nesbitt used to live off-grid near Salisbury, N.B., but was forced to move back to the city when her symptoms became too severe for her to sustain her lifestyle.

To Dr. Marrero, there are a few things that set all of these patients, including those identified in the initial cluster, apart from typical cases of known diseases, like Alzheimer’s disease, amyotrophic lateral sclerosis (ALS) or Parkinson’s disease.

In addition to being relatively young, many are clustered within certain geographic areas. While Dr. Marrero emphasized that he is not an epidemiologist, he said they appear to be concentrated in a few key locations, including the Acadian Peninsula, the Restigouche area, and rural areas in the vicinity of Moncton, extending southeast to Sackville.

He also finds the speed of his patients’ disease progression unusual. Alzheimer’s disease, for example, tends to develop over many years. By comparison, some of his patients experience initial episodes of rapid decline. Some have died within a few months or weeks of showing symptoms. (Dr. Marrero declined to say how many patients have died in total, but said he has reported each one of them to Canada’s Creutzfeldt-Jakob Disease Surveillance System.)

Their illnesses seem to evolve, affecting first the spinal cord, working up to the brain stem and then toward the frontal lobes, which are responsible for executive function, he said.

At a news conference in March, a group of his patients called for further investigation into whether environmental toxins are the cause of their illnesses.

Julie Hardy, 52, who began seeing Dr. Marrero in June, 2021, said not having an explanation for her illness is “terrifying.”

Ms. Hardy said she started having trouble with her balance around 2017. She now also suffers from blurred vision, poor memory and lack of strength, with her left side weaker than her right. She doesn’t have full control of her left hand. She also has trouble breathing, and her family doctor is trying to determine whether this is related to her brain function.

Ms. Hardy, who used to be a cook at a daycare, has been unable to work since 2021 because, she said, it was too dangerous to continue. She would forget things on the stove, and could lose her balance or fall over when bending down to pick up a child.

“It’s just frustrating, and nobody in the government seems to listen, to care,” she said.

Jillian Lucas, 37, said she was already dealing with post-concussion syndrome after suffering a head injury around 2018. Her stepfather was also experiencing neurological symptoms at the time. Ms. Lucas began developing symptoms similar to his after moving in with him and her mother in 2019.

Ms. Lucas’s stepfather had started seeing Dr. Marrero in October of that year, and she started seeing him, too, in the spring of 2021. Both she and her stepfather have insomnia, trouble balancing, memory problems, frequent nightmares, tremors and weakness. In spite of countless tests conducted or ordered by Dr. Marrero, she still doesn’t know the cause.

“One of the hardest things is not knowing, because I don’t have a road map,” Ms. Lucas said. “I wake up every day wondering if I’m going to lose another piece of myself.”

Julie Hardy, who now lives in Warren, N.S., suffers from memory loss, muscle atrophy and shortness of breath, among other undiagnosed health issues.

In e-mails to The Globe, New Brunswick’s Department of Health repeated that the province’s investigation had found no evidence of an unknown neurological syndrome, and that the Public Health Agency of Canada had supported this conclusion. It confirmed it had received correspondence from Dr. Marrero about the growing number of cases he is seeing. The department said it has been in contact with him and the Public Health Agency of Canada, and would respond accordingly if it determines any other action is needed.

While the health department noted that Dr. Marrero’s correspondence said he knew of at least 147 cases, the department said it had received detailed reports for only 14 of them since January, which it said are being reviewed. The department said it had reminded Dr. Marrero in March that he is legally required to submit details of new cases within seven days of identifying them.

Dr. Marrero said keeping up with the paperwork the health department requires – in addition to caring for patients and trying to find out what’s wrong with them – is more than he can handle on his own.

When Dr. Marrero first encountered an unusual neurological case around 2010, he said, he wasn’t alarmed, because rare diseases do exist. But he started noticing an uptick in atypical cases around 2017. By the spring of 2021, he was meeting with national and provincial experts to discuss these cases as many as five to 10 times a week.

During a news conference in March, 2021, New Brunswick’s Chief Medical Officer of Health, Jennifer Russell, told reporters that these patients were likely suffering from a new disease.

“We haven’t seen this anywhere else. And so it is of unknown etiology,” she said, adding that the symptoms were similar to Creutzfeldt-Jakob disease (CJD), a rare brain disease caused by abnormal, toxic prion proteins.

The province funded the creation of the MIND Clinic, a specialized clinic at Horizon Health Network’s Moncton Hospital, in April, 2021. There, Dr. Marrero provided care for patients who appeared to have the mysterious disease.

In the spring of 2021, several scientists, including Michael Strong, president of the CIHR and an expert in neurodegenerative diseases, told The Globe they expected an investigation would be complex and lengthy.

“If the worst-case scenario is that this is something new that we haven’t seen before, then truly bringing the whole-of-the-government response that’s working on this now, and bringing the academic community to bear on this ... it’s what we’ve got to do,” Dr. Strong said at the time.

During Dr. Marrero’s meetings with federal and provincial experts in 2021, one of the leading hypotheses that emerged, he explained, was that the cases were caused by some kind of environmental exposure, such as to a toxin called beta-methylamino-L-alanine, or BMAA.

BMAA, which is produced by cyanobacteria, or blue-green algae, has been hypothesized to have been the cause of a cluster of neurological diseases on the Pacific island of Guam at the end of World War II. A major cyanobacteria bloom occurred in 2017 at the Tower Road reservoir, which supplies water to the Moncton area.

Open this photo in gallery:

The Tower Road Reservoir near Turtle Creek, N.B., an area that supplies drinking water to Moncton.

Over the course of these meetings, Dr. Marrero said, he was asked to seek consent from the families of patients who had died to collect tissue samples of the patients’ fat, liver, kidneys and brains, to test for toxicity.

Susan Murch, a chemistry professor at the University of British Columbia-Okanagan who studies BMAA, confirmed that she and the Public Health Agency of Canada had discussed testing these tissues.

David Coulombe, a CIHR spokesperson, said his agency offered its support for the investigation by proposing to make use of a fund it keeps for research responses to emerging health threats.

The amount of funding was never settled, Mr. Coulombe said. And the testing of the tissues for BMAA was never done. Instead, Public Health New Brunswick released its final report in February, 2022, after a months-long investigation into what it called “a potential neurological syndrome of unknown cause.”

The public health agency had conducted a surveillance questionnaire that asked patients about their demographics, personal histories, activities and potential food and environmental exposures. And it had assembled an independent oversight committee, which included six neurologists. After analyzing the results of the questionnaire and the committee’s report, the agency concluded that the 48 patients who were considered a potential cluster, or group with similar characteristics, were not actually suffering from a common unknown illness.

The oversight committee reviewed patients’ medical files and found that they likely had known diseases that had simply been misdiagnosed. Some patients and their families have challenged this finding, saying they were never examined by committee members and that the diagnoses proposed by the oversight committee were for illnesses – including cancer, Alzheimer’s disease and Lewy body dementia – that didn’t fit their circumstances or had already been ruled out through tests.

Public Health New Brunswick’s final report also emphasized that 46 of the 48 cases were referred by a single neurologist. Though it did not mention him by name, this neurologist was Dr. Marrero. “Unfortunately, many of the theories which caught people’s attention were based on speculation, uncorroborated opinions and in the absence of a thorough analysis of epidemiological and clinical information,” the report said.

Last summer, Dr. Marrero was informed that he would no longer be working at the MIND Clinic. Since July, 2022, he has been seeing patients at his primary practice, at Dr. Georges-L.-Dumont University Hospital Centre, in Moncton.

Asked why Dr. Marrero was replaced at the MIND Clinic, Jody Enright, medical director for the Moncton-area Horizon Health Network, did not answer directly. She said in an e-mail only that Dr. Marrero had returned to his primary practice.

When Horizon informed Dr. Marrero’s patients that he would no longer be working at the MIND Clinic, it offered them two options: they could continue to be seen by him, or be seen by a new neurologist at the MIND Clinic, where their care would also be supported by an interdisciplinary team, including nurses, a social worker, a neuropsychologist and health professionals in psychiatry, speech language pathology, physiotherapy and occupational therapy.

Many patients opted to stay with Dr. Marrero, and they lost access to those other services. In her e-mailed statement, Dr. Enright did not answer a question about why this had occurred. She said that while she could not comment on specific cases, in general those who decided to stay with the MIND Clinic have received second opinions, diagnoses and continuing interdisciplinary care and follow-up.

Luc LeBlanc, one of the New Brunswickers suffering from the unexplained disorder, shows the muscle atrophy in his arms in Dieppe, N.B.

Dr. Marrero disputes any suggestion that he was a lone doctor crying wolf. In most cases, he said, he has not been the only doctor, nor the only neurologist, who has seen these patients. Several of his patients and their family members confirmed this to The Globe.

Luc LeBlanc, 43, a patient of Dr. Marrero’s who was in the initial cluster, said he thought he had finally found an explanation for his illness when he sought a second opinion from a neurologist in Toronto. The visit was facilitated by CBC’s The Fifth Estate in November, 2021. That neurologist told him she could only speak to his case, but that she believed his symptoms – which include memory loss, trouble with balance and coordination, and a persistent burning sensation in his skin – were not an unknown neurological syndrome. Rather, she told him, they were attributable to a serious car accident in 2018, and to stress.

“I took that as a win, and tried to move on,” Mr. LeBlanc said.

But his health has worsened. Mr. LeBlanc said muscles throughout his body have atrophied, and that his family doctor has expressed concern about his dramatic loss of body mass. He has experienced breathing problems and hearing loss. He said he is still seeing Dr. Marrero, though not regularly, and that he remains in contact with the Toronto neurologist, with whom he has discussed the possibility of being referred to another neurologist in New Brunswick, or returning to Toronto for another evaluation.

“I kind of feel bad, because New Brunswick is really saying, ‘You’re sick. We don’t care. Try to find some help elsewhere,’” he said. “It’s a bad approach.”

Dr. Murch, the University of British Columbia BMAA expert, said further investigation is needed. She emphasized that her lab is for research, and not a clinical lab intended for diagnostic tests. She added that she had been waiting for ethics approval to test patients’ tissue samples when a decision was made not to send the samples to her. She thinks these tests should still be done.

“I do think more testing is needed, whether it’s done in my lab or whether it’s done in another lab,” she said. But, she added: “We need to look at the whole food web, and just testing the patients is not enough.”

She explained that diagnosing a neurological disease is difficult, and that sometimes the pathology – the way cells, tissues and organs respond to illness and injury – can be misleading. For example, a patient can have mixed pathologies, with symptoms of several diseases. “So the New Brunswick conclusion that these were all patients who had some other illnesses is based on incomplete information,” she said.

Mr. Coulombe, the CIHR spokesperson, said his agency was informed by Public Health New Brunswick in May, 2021 that its help would not be needed. He said CIHR remains ready to provide research support and advice if its assistance is requested by those leading the investigation in New Brunswick.

The Public Health Agency of Canada also said that, while it is available to support provinces and territories, the government of New Brunswick is the lead authority on this issue.

Back in New Brunswick, Dr. Marrero said he is appealing for federal and provincial help. As he awaits it, he said, he is still trying to find answers.



Dr. Marrero says he has noticed a jump in unusual cases, which are initially believed to be Creutzfeldt-Jakob Disease (CJD) or a similar disease.

February, 2020

Canada’s Creutzfeldt-Jakob Surveillance System (CJDSS), Public Health New Brunswick and regional health authorities meet to discuss the number of CJD cases observed in the province.

March, 2020

The World Health Organization declares a novel coronavirus pandemic.

September 2020

According to Public Health New Brunswick, 29 cases of atypical, rapidly progressive dementia, including several cases of CJD, are discussed at a meeting with CJDSS and Dr. Marrero.

December 2020

The cases in question are not considered CJD, and are thought to be a cluster of a neurological syndrome of unknown cause. Public Health New Brunswick says there are 33 cases.

February 2021

A multidisciplinary team of provincial and national partners is created. Public Health New Brunswick says it is taking the lead on the investigation.

March 2021

CBC News and Radio-Canada report that a memo from the office of the province’s chief medical officer has been sent to health professionals, notifying them of the existence of a cluster of unusual neurological cases.

April 2021

Public Health New Brunswick says the cluster is closed at 48 cases. The MIND Clinic, a specialized clinic for these patients, is created with funding from the province’s Department of Health.

May 2021

Meetings of national and provincial experts come to a halt. Public Health New Brunswick says it is pausing recurring meetings with federal and provincial experts, and has asked CIHR to pause its main activities related to the file.

October 2021

Dorothy Shephard, the province’s health minister at the time, tells a news conference that an epidemiological study has found no evidence of a common exposure that could have triggered a potentially new neurological syndrome. She says provincial health officials believe many of the cases were misdiagnosed by a single neurologist.

February 2022

Public Health New Brunswick releases its final report, concluding there is no neurological syndrome of unknown cause. Dr. Marrero sends a letter to federal and provincial authorities, saying he has received more than 100 new requests to see patients with atypical progressive neurological symptoms.

July 2022

Dr. Marrero is replaced at the MIND Clinic. His patients are given a choice to either stay with him, or be seen by a new neurologist at the MIND Clinic, where they will have access to other health services.

January 2023

Dr. Marrero sends another letter to federal and provincial authorities, asking for help.

March 2023

A group of patients holds a news conference, calling on the New Brunswick government to allow the Public Health Agency of Canada to investigate whether environmental toxins are the cause of their illnesses. In response, the New Brunswick Department of Health says the Public Health Agency of Canada supported the results of the province’s investigation, which found no evidence of a common cluster. It says it will ask for more information about each of the additional cases.

July 2023

New Brunswick’s Department of Health confirms it has received Dr. Marrero’s correspondence. It says while he suggested he knew of 147 unusual cases, it has received only 14 detailed reports.

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