Lytico-Bodig disease
Lytico-Bodig disease, sometimes spelt Lytigo-bodig[1] is a neurological disease that exists on the Island of Guam.
It resembles both Amyotrophic lateral sclerosis (ALS) (more commonly known as Lou Gehrig's disease) and Parkinson's Disease. First reports of the disease surfaced in 3 death certificates on [Guam] in 1904. These death certificates made some mention of paralysis. The frequency of cases grew amongst the Chamorro people on Guam until it was the leading cause of death between 1940 and 1956. The symptoms range from strongly resembling ALS to those resembling Parkinson's Dementia Complex (PDC). The symptoms tend to show themselves between the ages of 25 and 40. Many victims aren't able to speak off their own accord but they can speak coherently and fluidly when spoken to. It is commonly thought that the disease is caused by toxins in the Cycad trees which are prevalent on Guam.
The eminent neurologist Oliver Sacks detailed this mysterious condition in his book Island of the Colourblind. Oliver Sacks has since discovered that a local species of fruit bat which is now largely extinct due to overhunting had been feeding on Cycads and concentrating the poison in its bodyfat. It's believed that consumption of the fruit bat transferred a low level, but high enough level of the poison to lead to long term toxicity.[2]