Gajdusek was born at Yonkers in New York and educated at the University of Rochester and at Harvard, where he obtained his MD in 1946. He specialized in pediatrics, working at Harvard, the Pasteur Institute in Teheran, and the Walter and Eliza Hall Institute for Medical Research in Melbourne, before joining the National Institute of Health in Bethesda, Maryland, in 1958. Since 1970 he was with the National Institute of Neurological Diseases.

In 1963 he made an intriguing discovery that could well have profound consequences for the control of a number of serious but little-understood diseases. In the 1950s he began studying the Fore people of New Guinea, a supposedly cannibalistic tribe who suffered from a very localized neurological complaint they called ‘kuru’. With the aid of the district medical officer, who first drew his attention to the disease, Gajdusek spent much of the next ten years among the Fore looking for the cause of kuru. He suspected the disease was transmitted by the Fore custom of ritually eating parts of the brain of their deceased relatives so he collected samples from the brains of several kuru victims.

Failing to detect any obvious signs of an organism in the brain tissue he injected filtered extracts into the brains of chimpanzees and waited. After about 12 months the disease at last appeared. This was the first of what were known as ‘slow virus infections’ to be observed in humans. By 1968 Gajdusek and his colleagues had shown that kuru was not unique and that the rare neurological complaint Creutzfeldt-Jakob disease, a presenile dementia, is transmitted after a comparable delay.

For his work on kuru Gajdusek shared the 1976 Nobel Prize for physiology or medicine with Baruch Blumberg. The prize itself he used to set up a trust for the education of the Fore people. Gajdusek, who was unmarried, has also adopted 16 boys while on his expeditions to the Pacific, and brought them up in America.