The Island of the Colorblind

There were, however, examples of animals poisoning themselves en masse, unprotected by any ‘instinctive’ knowledge. Cattle which browse on bracken may come down with a neurological disorder which resembles beriberi or thiamine deficiency – this is caused by an enzyme in bracken which destroys the body’s thiamine. Horses in the Central Valley of California have come down with parkinsonism after eating the toxic star thistle. But the example which Whiting especially remarks is that of sheep and cattle, which are extremely fond of cycads; indeed, the term ‘addiction’ has been used in Australia, where some animals will travel great distances for the plants. Outbreaks of neurocycadism, she noted, had been recorded in Australian cattle since the mid-nineteenth century. Some animals, browsing on the fresh young cycad shoots (this would especially occur in dry seasons, when other plants had died off, or after fires, when cycads would be the first plants to reshoot new leaves) would get a brief, acute gastrointestinal illness, with vomiting and diarrhea – this, if not fatal, would be followed by complete recovery, as with acute cycad poisoning in man. But with continued browsing on the plants, neurocycadism would develop; this would begin as a staggering or weaving gait (hence the colloquial name ‘zamia staggers’), a tendency to cross the hind legs while walking, and finally complete and permanent paralysis of the hind limbs. Removing the animals from the cycads at this stage was of no use; once the staggers had set in, the damage was irreversible.

Could this, Whiting and Kurland wondered, be a model for lytico? The idea was intriguing: fadang had been a common food before the war and, during the Japanese occupation, was used in much larger quantities, as other crops were requisitioned or destroyed. After the war, fadang consumption declined sharply because of the greater availability of imported wheat and corn flour – this, it seemed to them, could provide a very plausible scenario for the disease, why it had peaked immediately following the war, and steadily declined thereafter, an incidence which ran parallel to the use of fadang.

But the cycad theory was problematic on several grounds. First, there were no other known examples, outside Guam, of a chronic human illness ascribable to the use of cycads, despite their very wide and long use throughout the world. It was, of course, possible that there was something special about the Guam cycad, or some special vulnerability to it among the Chamorros. Second, the period of decades which might elapse between exposure to the cycads and the onset of lytico-bodig, if indeed the two were connected, was something which had no precedent in poisonings of the nervous system. All known neurotoxins acted immediately or within a few weeks, the time needed to accumulate to toxic levels in the body or for neurological damage to reach critical, symptomatic levels – this was so with heavy metal poisoning, as had occurred in the notorious Minamata Bay paralysis, with the neurolathyrism in India caused by eating the toxic chickling pea, and with the neurocy-cadism in cattle.[56] But these seemed quite different from a poison which, while causing no immediate effects, might lead to a progressive degeneration of particular nerve cells starting many years later. No such delayed toxic effect had ever been described – the very concept strained belief.

We set off again, to return to Umatac; John had more patients he wanted me to meet. He loved showing me patients, he said, taking me on house calls with him – I also loved this, seeing his energy, his neurological skill, and, even more, the delicate feeling, the caring, he showed for his patients. It took me back to my own growing up, when I would go out on house calls with my father, a general practitioner – I had always been fascinated by his technical skills, his elicitation of subtle symptoms and signs, his knack for making diagnoses, but also by the warm feeling which manifestly flowed between him and his patients. It was similar, I felt, with John; he too is a sort of GP – a neurological GP, an island GP – for his hundreds of patients with lytico-bodig. He is not just a physician to a group of individuals, but physician to a whole community – the community of the afflicted Chamorros and their relatives who live in Umatac, Me-rizo, Yona, Talofofo, Agat, Dededo, in the nineteen villages which are scattered over Guam.