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02 Apr 2015

Researchers are investigating whether blue-green algae is driving a dramatic upsurge in the incidence of motor neurone disease (MND) in the Riverina.

Scientists suspect the algae, which blooms intermittently in inland waterways, could be behind an exceptionally high cluster of MND cases in the irrigation farming region in recent decades.

The issue came to the attention of researchers following a sharp increase in the number of MND-related deaths in the area in the past 25 years.

One of the investigators, Macquarie University Professor of Neurology Dominic Rowe, said the numbers of MND deaths had jumped from one in 500 fatalities in 1986 to one in 180 in 2011.

The urgency of the research has been underlined by the fact that more than 90 per cent of motor neuron diseases have no known cause or cure. The disease kills motor neurons in the brain and spinal cord, progressively paralysing the body.

Professor Rowe said blue-green algae was one theory they were chasing.

“This is a theory that’s been around 30 years. It has only been revitalised in the last couple because of the increase,” Professor Rowe said. “If blue-green algae is a trigger we need to know what happens.”

Suspicion that blue-green algae may cause MND is not new. A study last year by researchers from the University of Technology Sydney and the Institute of Ethnomedicine in the United States found a link between the ingestion of food or water contaminated by blue-green algae and motor neurone disease.

Blue-green algae or cyanobacteria produces a neurotoxic amino acid called β-methylamino-L-alaine or BMAA. The researchers discovered that BMAA mimics an amino acid called serine that is used to make human proteins.

Lead author of the study, Dr Rachel Dunlop from the University of Technology Sydney, said the similarities between serine and BMAA mean that when the toxin is present in the body it can be mistaken for serine and incorporated into human proteins. This damages the proteins and inhibits their function, eventually causing the death of the cell.

“Common among all neurodegenerative diseases is the problem of clumps of proteins overloading cells and forcing them to ‘commit suicide’,” Dr Dunlop said.

“This research reveals that BMAA can also trigger this process.”

BMAA was originally identified in Guam after the Indigenous people, the Chamorros, were found to develop motor neurone disease up to 100 times more often than other people. The Chamorros used seeds from cycad palms to make flour, and regularly ate fruit bats, which also ate the seeds. Both these foodstuffs contained BMAA.

Since then, research has revealed increased incidences of MND in people who live near lakes with frequent cyanobacteria blooms, among consumers of contaminated shellfish, and in soldiers deployed during the First Gulf War, because the desert sands they walked over had a crust of cyanobacteria.

Dr Dunlop said the research showed just how important it was for people to avoid contact with algal blooms.

“Blue-green algae is ubiquitous in Australia but not everyone has motor neurone disease, so there are likely other factors involved in triggering the disease,” Dr Dunlop said. “But when people are warned to stay away from blue-green algae they should heed the warning.”

The research by Dr Dunlop was published in the journal PLOS ONE.

 

Kirsty Waterford


Published: 02 Apr 2015