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The Canadian province of New Brunswick is grappling with a cluster of patients suffering from a mysterious neurologic disease that to date has afflicted more than three dozen of its residents.
Jennifer Russell, MD, the province’s chief medical officer, said 43 individuals are suffering from a progressive neurologic syndrome of unknown origin, with symptoms similar to those of prion diseases like Creutzfeldt-Jakob disease (CJD) and its variants, including bovine spongiform encephalopathy, also known as mad cow disease.
On March 17, the Canadian Broadcasting Corporation (CBC) reported on an internal memo sent by Russell to the New Brunswick Medical Society and other medical associations outlining the details of the cases.
The memo, dated March 5, reports the first known case was diagnosed as far back as 2015. Eleven more cases came to light in 2018, followed by another 24 cases in 2020. Another seven were reported this year. Five people have died.
“A New Disease”
The memo goes on to say that while the cluster of cases may resemble CJD, tests have so far ruled out known prion diseases. Now researchers are looking into the possibility that the cases represent a new variant of prion disease, or perhaps a new disease entirely.
During a public health update on March 18, Russell confirmed that it is “most likely a new disease,” adding, “we haven’t seen this anywhere else” in Canada.
The province’s cases have clustered around the city of Moncton in southeast New Brunswick (eight cases) and a region known as the Acadian Peninsula in the northeast part of the province (35 cases). Although overall median age of cases is 59 years (54 years in women), the memo notes the disease affects all age groups. To date, the cases have been equally distributed among men and women, the memo adds.
A team of researchers headed by neurologist Alier Marrero, MD, of the Dumont University Hospital Centre in Moncton, is looking into this puzzling situation.
In an interview with Medscape Medical News, Marrero said the disease seems to be born of environmental causes.
“We have not yet been able to come up with causative agent, except that everything that we have analyzed so far suggests this is an environmental exposure of some kind that is acquired through food, water, air, professional activities, or leisure activities,” he said.
“There’s also seems to be some geographic clustering, which suggests environmental exposure as well,” Marrero added. “But since we don’t have a picture of the whole province yet, it is slightly premature to talk about that.”
Diagnosing the disease remains a challenge, as initial symptoms have been largely nonspecific. These include behavioral changes, sleep disturbances, unexplained pain, visual hallucinations, coordination problems, unexplained hair loss, involuntary muscle twitching, formication (a sensation that feels like small insects crawling under the skin), ataxia, and brain atrophy.
“What we do know is that once the patients are exposed to this and the symptoms begin, they continue in a predictable manner,” he said. “So we can now characterize the symptoms, and we know what they look like and what to expect.
“The progression typically is 18 to 36 months, but it could be variable as we don’t have enough data yet to predict individually for each patient,” Marrero added. “They can also be adults of any age; we’ve seen both very young patients and elderly patients.”
No Public Health Risk
According to the CBC report, Russell said the situation does not currently pose a risk to public health. Nevertheless, both she and Marrero urged New Brunswick physicians and residents to be on the lookout for symptoms of the disease and report them directly to Marrero’s institution.
“The province has suggested a referral system to a single clinic so we can evaluate the patient in the same manner, as well as diagnose and rule out all the conditions that we find when we’re investigating these patients,” he said.
Suspected cases undergo a battery of testing to rule out other neurologic disorders with similar symptoms. An important part of these analyses, Marrero said, will be extensive lifestyle questionnaires aimed at unearthing a common environmental link.
In recent days, a growing number of experts have been engaged in the effort to help solve the mystery. On Tuesday, CBC reported that federal scientists have joined New Brunswick’s efforts, including Canada’s national CJD Surveillance System. Marrero and his colleagues are also sharing data with colleagues in the neighboring provinces of Nova Scotia and Quebec, as well as the US state of Maine, which borders New Brunswick to the south.
“It’s a collective effort that includes many experts,” Marrero said. “We’ve been having meetings with experts from public health, field epidemiology, zoonosis, environmental health, veterinarians, and toxicology.”
Yet despite these efforts, the syndrome remains a mystery.
“It’s been postulated by some experts that it may be a toxic, non-proteinogenic amino acid linked to neurodegeneration,” Marrero noted. “But at this point it still remains hypothetical. We are open to all possibilities at this time. “But whatever it is, it’s not going away.”
To date, no other cases have been reported in Canada.
Créditos: Comité científico Covid