Blue-green algae to be investigated as possible cause of mystery neurological disease

A bacteria blamed in previous years for killing dogs that consumed it will be investigated as a potential cause of a mystery neurological brain disease observed in New Brunswick that has killed six people, says a researcher involved in the work.

Researchers studying the disease plan on looking at cyanobacteria — also known as blue-green algae — and another toxin present in the region to see if there's a link between them and the disease, said Dr. Neil Cashman, a professor in the University of British Columbia's faculty of medicine, who's helping investigate the illness.

Speaking on CBC's Information Morning Moncton, Cashman said the other toxin being looked at is domoic acid, which in the 1980s was associated with an outbreak of neuro-degeneration in persons who'd consumed mussels on P.E.I.

"So those are two environmental toxins that can present with these sorts of syndromes, and they are on the list to be studied and to determine if there has been exposure to these two toxins in New Brunswick," he said.

The neurological disease cluster was first reported on in March, when Radio-Canada obtained a memo from Public Health to medical professionals.

There have been a total of 48 cases recorded since 2013, with them being concentrated among people living in the Moncton and Acadian Peninsula regions.

Public Health is working with several provincial and federal agencies to investigate the disease cluster, including the New Brunswick Department of Agriculture, Aquaculture and Fisheries, and the Public Health Agency of Canada.

The disease resembles prion diseases — a group of neurodegenerative diseases caused by proteinaceous infectious particles, or prions — such as Creutzfeldt-Jakob disease. However, tests have ruled that out.

Cashman, who specializes in prion diseases, has been looking into the New Brunswick cluster, as an adviser with Health Canada's Creutzfeldt-Jakob Disease Surveillance System.

Cashman said he and other researchers are "casting a wide net" to determine the cause in New Brunswick, but pointed to the two toxins as starting points for the investigation.

He said cyanobacteria produce a compound called BMAA, which can become concentrated in fish and shellfish.

Once those are consumed in high quantities, Cashman said BMAA can "masquerade" as a natural amino acid and get incorporated into the proteins of humans.

Cyanobacteria was ruled as the cause of death of four dogs that died after going near the St. John River around Fredericton in the summers of 2018 and 2019.

The bacteria is also present in various water bodies across the province, including in the Turtle Creek watershed, which is the drinking water source for Moncton, Dieppe and Riverview.

As for domoic acid, which was linked to an outbreak in persons who consumed mussels in the 1980s, Cashman said those persons exhibited seizures and loss of consciousness within the same day of consuming them.

However, he said it's possible that the same acid in low doses over a long period of time "might lead to a more chronic syndrome which would be consistent with the New Brunswick outbreak."

Asked about potentially avoiding the disease, Cashman said he doesn't have an answer.

"What I've told you about for, you know, shellfish, toxins or cyanobacteria, of course, if those are implicated, then there are ways to avoid them, but you can't avoid everything in your environment," he said.

"And not knowing precisely the cause — working very hard on it — but not knowing precisely the cause, it's kind of dishonest to provide advice at this stage of the investigation."