Ride For Life: River water to blame for Guam's terrifying ALS-PDS

River water may be the cause of a rare and terrifying brain disease on the Pacific island of Guam which leaves its victims virtually motionless shells, according to scientists.

While previous theories on the cause of lytico-bodig -- now known as amyotrophic lateral sclerosis/parkinsonism-dementia (ALS-PDS) -- said it may have been the result of locals eating giant bats, a new study says bacteria found in rivers may be to blame.

ALS-PDS has in the past wiped out some 10 percent of Guam's indigenous Chamorro population while up to 70 percent may be predisposed to it.

Similar diseases have struck on the Kii Peninsular in Japan and the southern lowlands of West Papua (Irian Jaya) in Indonesia -- each around 3,500 kilometres (2,200 miles) from Guam. ALS-PDS attracts intense scientific interest because it is regarded as key to finding a cure to Alzheimer's and Parkinson's diseases and Creutzfeldt-Jakob disease, the human equivalent of mad cow disease.

Last year the celebrated New York neurologist Oliver Sacks published data saying the disease was the result of Chamorro eating bats known as flying foxes which had consumed palm seeds.

But a new study by William Miller and Richard Sanzolone of the US Geological Survey says that at certain times of year the algae or bacteria releases toxins into the water.

"It would be the ingestion of the toxins, ... particularly over a long period of time, which would be responsible for the diseases," they said.

The water used to be drunk untreated but it is now filtered through activated carbon which would account for the previous high rates of incidence, the pair said.

The disease was first identified by US doctors stationed on the island in 1945, at the end of the Japanese occupation.

The name comes from paralytico, which is what the locals call the condition, and for a man who ran a bodega (food and wine shop) and acquired the condition.
Among the symptoms are rigid muscles, a marked stoop, slow speech and forgetfulness, hand tremors and dementia.

The number of cases reached a height in the 1940s when it was the main cause of adult death, but it now only occurs in older adults and rarely in individuals born after 1960.

The highest incidence of the disease was in three southern villages built around rivers that the new study believes may have contained a toxin.

The geologists found no particular imbalance of chemicals or minerals naturally occurring in the rivers, but noted that ALS-PDS only occurred in villages on the volcanic portion of the island, and not the limestone section.

They found the rivers had large areas covered by filamentous material, both alive and dead. It was either algae or cyan bacteria.

A small number of algal species produce hepatoxins or neurotoxins.
"Neurotoxins affect the nervous and respiratory systems that can cause muscle tremors, stupor, staggering, rapid paralysis and respiratory failure," said the study.

The authors say the geology of Kii in Japan and West Papua are dissimilar to Guam but they may share the toxin agent.

"(Species) of algae of cyan bacteria responsible for the disease may exist in this part of the Pacific.... The three areas contain indigenous people that have existed there for long periods of time.

"These indigenous people in the past (and perhaps presently) would have obtained untreated water from local steams."

They called for further studies and in the meantime warned people to avoid contact with stream water.

Sacks earlier linked it to the eating of flying foxes, a core part of Chamorro custom. He had found that the flying foxes were particularly fond of cycad seeds.
Eating the bats became highly popular and by the late 1970s the species had been hunted to near extinction.