Soon we were whizzing down the road to Agat – a drive which made me slightly nervous, for John was now launching into another reminiscence, a very personal history of his own encounter with the Guam disease, the vicissitudes of his thought, his work, and his life on Guam. He spoke with passion, and with vehement, darting gestures, and I feared his attention was not fully on the road.

‘It’s an extraordinary story, Oliver,’ he started, ‘whatever way you look at it – in terms of the disease itself, and its impact on the people here on the island, the tantalizing, round-and-round search for its cause.’ Harry Zimmerman, he said, had first seen it in 1945, as a young navy doctor arriving after the war; he had been the first to observe the extraordinary incidence of ALS here, and when two patients died he was able to confirm the diagnosis at autopsy.[46] Other physicians stationed on Guam provided further, richer documentation of this puzzling disease. But it required perhaps a different sort of mind, the mind of an epidemiologist, to see the greater significance of all this. For epidemiologists are fascinated by geographic pathology, so to speak – the special vicissitudes of constitution or culture or environment which predispose a population to a specific disease. Leonard Kurland, a young epidemiologist at the National Institutes of Health in Washington, realized at once when he read these initial reports that Guam was that rare phenomenon, an epidemiologist’s dream: a geographic isolate.

‘These isolates,’ Kurland was later to write, ‘are sought constantly, because they stimulate our curiosity and because the study of disease in such an isolate may demonstrate genetic or ecological associations that otherwise might not be appreciated.’ The study of geographic isolates – islands of disease – plays a crucial role in medicine, often leading to the identification of a specific agent of disease, or genetic mutation, or environmental factor that is linked to the disease. Just as Darwin and Wallace found islands to be unique laboratories, hothouses of nature which might show evolutionary processes in an intensified and dramatic form, so isolates of disease excite the epidemiological mind with the promise of understandings to be obtained in no other way. Kurland felt that Guam was such a place. He shared his excitement with his colleague Donald Mulder, at the Mayo Clinic, and they decided to go to Guam right away, to launch a major investigation there, with all the resources of the NIH and the Mayo.

This was not, John suspected, just an intellectual moment for Kurland, but an event which changed his life. His initial visit, in 1953, opened intoxicating horizons for him – a love affair, a mission, which was never to stop. ‘He is still writing and thinking about it, and coming here,’ John added, ‘forty years later – once it gets to you, it never lets you go.’

When Kurland and Mulder arrived they found more than forty cases of lytico on the island, and these, they felt, were only the most severely affected, milder cases probably having escaped medical attention. A tenth of all the adult Chamorro deaths on Guam were due to the disease, and its prevalence was at least a hundred times greater than on the mainland (in some villages, like Umatac, it was over four hundred times greater). Kurland and Mulder were so struck by this concentration of the disease in Umatac that they wondered whether it might have originated here and then spread to the rest of the island. Umatac, John pointed out, had always been the most isolated, least modernized village on Guam. There was no access by road in the nineteenth century, and even in 1953, the road was often impassable. Sanitary and health conditions were poorer than anywhere else on the island at that time, and traditional customs remained very strong.

Kurland was also struck by the way in which certain families seemed predisposed to get lytico: he mentioned one patient who had two brothers, a paternal uncle and aunt, four paternal cousins, and a nephew with the disease (and he observed that health records back to 1904 showed this family to have been singled out even then). Many of the family, John said, were now his patients. And there were other families, like the one we were on our way to see, who seemed particularly vulnerable to the disease.