No cause of death has been released, but he had suffered for years from congestive heart failure, according to his biographer and former student, Dr. Robert Klitzman of Columbia University.
An energetic and intellectual researcher, Gajdusek often said he was more proud of his anthropological studies among the Fore and Anga people of Micronesia than he was of the research that brought him the ultimate prize.
But blinded by his hubris and self-admitted pedophilia, he spent the last decade of his life in exile in Europe after his arrest and imprisonment for molesting one of the more than 50 children he brought to the United States, adopted and educated.
Intrigued by his two years of studying rabies, plague, arbovirus infections and scurvy at the Institut Pasteur in Tehran, Gajdusek scoured the Hindu Kush, the jungles of South America and the mountains, swamps and high valleys of Papua New Guinea and Malaysia searching for a rare disease he could make his own.
He found it when he met Dr. Vincent Zigas, an Estonian medical officer who served the Fore people in eastern Papua New Guinea. Zigas introduced him to the Stone Age people, who were suffering from a mysterious malady that they called kuru, from the Fore word meaning "to shake."
The disease, which caused trembling, sporadic fits of laughter and madness before inevitably leading to death, affected one out of 10 people in the 35,000-member tribe. Autopsies showed that victims' brains were riddled with gaping holes, making their once solid organs resemble sponges -- leading to the general name spongiform encephalopathies for diseases in the class.
The disease was not believed to result from an infection, because victims did not suffer a fever and there were no signs of inflammation -- both indications of classical infections. Most researchers thought kuru was either hereditary or the result of a dietary deficiency.
Gajdusek described the disease in a 1957 issue of the New England Journal of Medicine and took samples back to his lab at the National Institutes of Health in Bethesda, Md., for study. He concluded that the disease was spread during an ancient funerary ritual when women and children consumed the brains of the deceased.
Since that practice was formally banned in 1959, no new cases of the disease have appeared except in those who were exposed before the ban took effect.
Gajdusek injected samples of diseased human brain tissue into a variety of small animals hoping to reproduce the disease, but without success.
He ultimately obtained some chimpanzees and injected them as well. At first, that too yielded no results. But after periods ranging from 1 1/2 to three years, the animals began to develop symptoms similar to those exhibited by the Fore.
In a 1966 paper in the journal Nature describing the transmission experiments, Gajdusek dubbed the infectious agent a "slow, unconventional virus."
Further studies by Gajdusek and others showed that a similar agent was responsible for a disease in sheep called scrapie, another malady in humans called Creutzfeldt-Jacob disease and the variant form of Creutzfeldt-Jacob commonly known as mad cow disease.
Eventually, neurologist Stanley Prusiner of UC San Francisco identified the infectious agent as an unexpected rogue form of protein called a prion -- a feat that won him his own Nobel Prize in 1997.
Prions are mis-folded forms of protein that, through mechanisms not yet understood, induce other proteins to assume similar shapes, disrupting cellular metabolism and killing cells in the brain.
Prions cannot be disrupted even in boiling water, are not susceptible to drug treatment and cannot be classified as living because they contain no DNA or RNA. They are also not recognized by the immune system as foreign, so the body cannot fight them off as it would any other infectious agent.
Some researchers now believe that prions may also be involved in producing dementia and perhaps even in triggering cancer. Gajdusek later helped other researchers find genetically isolated populations that helped shed light on the causes of hermaphroditism, Huntington's disease and other rare illnesses.
Daniel Carleton Gajdusek was born Sept. 9, 1923, in Yonkers, N.Y., the son of a Slovak father and a Hungarian mother. As a child, he demonstrated a remarkable interest and skill in science, stimulated by his aunt, Irene Dobroscky, who worked at the Boyce Thompson Institute for Plant Research in New York.