Guam’s mystery illness
Scientists have an intense curiosity. That’s their agenda – a desire to explain how things work. Much research resembles a detective novel of theories and after an experiment or two, an alibi or not.
Oliver Sacks, the doctor dramatized in the film “Awakenings,” is fascinated by a disease on the island of Guam known locally as Lytico-Bodig. It resembles ALS (motor neuron disease), Parkinson’s, Alzheimer’s or all three, and appeared suddenly at the turn of the century and is now disappearing. At its peak, Lytico-Bodig killed one in 10 of the adult native Chamorros.
In his book “Island of the Color Blind,” he visits a doctor on Guam and combines his knowledge of neurology, botany and anthropology to try to come up with a working theory. It’s a fascinating book, but disappointingly finishes without solving the crime.
Their best hypothesis involved the eating of the fruit of cycad trees (a primitive plant). These nuts contain a potent nerve poison in the form of an amino acid called BMAA, and the Chamorros live off flour made from these nuts. Prolonged exposure could lead to degenerative neuron damage, they figured.
This theory fell apart, though. The natives know cycads are toxic and wash and dry the flour several times. This removes almost all the BMAA. To get a significant dose, they’d have to eat tons per week.
It looked like any explanation would vanish with the disease. Lytico-Bodig would remain a freak affliction of a couple of generations and an unsolved puzzle.
Continued sleuthing has put BMAA back in the spotlight. Their knowledge of the disease, the poison, the fruit needed one more link to complete the circle: A fruit bat.
Fruit bats are a traditional delicacy on Guam. They’re boiled in coconut milk and eaten just like that, skin and all. A sort of an “Addam’s Family” breakfast cereal. Fruit bats live off cycad nuts and concentrate the toxin. Eating a bat is the equivalent of eating a ton of cycad flour. They had their smoking gun.
This also explains the disease’s rise and decline. In 1898 the U.S. acquired Guam in the Spanish-American War, bringing guns and capitalism to the natives. Fruit bats live at the tops of trees and have good eyes. Sneaking up with a net was tough, making boiled bat a delicacy eaten only at special occasions.
Guns changed that. People started to eat a lot of bats with two consequences: Lytico-Bodig appeared, and the bats went extinct. The latter may have been helped by the introduction of the brown tree snake in 1950, a smothering pest that has decimated all of Guam’s birds, lizards, bats, etc.
Now Guam’s Chamorros import their fruit bats from cycad-free islands and no one born after 1961 has the disease. Curiosity continues, though, and the BMAA in cycad fruits is now known to originate in a symbiotic cyanobacteria that fixes nitrogen in the plant’s roots. The cycad transports the BMAA to its seeds, perhaps to protect them from herbivores. Cyanobacteria will now be a suspect in other outbreaks of similar motor neuron diseases.
I find this an interesting and exotic example of how technology and progress interact without environment to produce completely unexpected results.
Mad cow is another illustration, in which factory-farming practices created a new situation leading to the spread of BSE. This isn’t a new disease. Variants have existed probably forever. We typically called it Creuzfeld-Jakob disease. There’s a link to southeastern Asia here, too. Cannibals there suffered from outbreaks of kuru – being possessed by the bad spirits of the ancestors or enemies you ate. Kuru is another prion disease spread by eating infected brains, and very similar to mad cow.
There are arguments for AIDS becoming widespread in pre-World War II Africa due to increased mobility and mass inoculation programs that didn’t understand the need for better syringe hygiene. Before that, any outbreaks could have been very localized and isolated. Blood banks are a great resource, but we ignorantly spread AIDs through these for awhile, too.
Ebola continues to flare up in Africa through the selling of bushmeat (chimps and other apes) that comes from infected ape populations. The apes are being devastated by more and more outbreaks, and no one knows why.
The world is a very complex and connected place. The rise and fall of diseases as we change their and our environment is only one example of this. Expect more unknown and unintended consequences, some good and some bad. And keep an open ear to the theories of scientists, who are only trying to connect the dots of our world.