Gajdusek’s father, Karol Gajdusek, was a butcher, an ethnic Slovak from Büdöskő, Kingdom of Hungary (now Smrdáky, Slovakia). His maternal grandparents, ethnic Hungarians of the Calvinist faith, emigrated from Debrecen, Hungary. Gajdusek was born in Yonkers, New York, and graduated in 1943 from the University of Rochester, where he studied physics, biology, chemistry and mathematics. He obtained an M.D. from Harvard University in 1946 and performed postdoctoral research at Columbia University, the California Institute of Technology, and Harvard. In 1951, Gajdusek was drafted into the U.S. Army and assigned as a research virologist at the Walter Reed Army Medical Service Graduate School. In 1954, after his military discharge, he went to work as a visiting investigator at the Walter and Eliza Hall Institute of Medical Research in Melbourne, Australia. There, he began the work that culminated in the Nobel prize.

In his 1977 paper “Unconventional Viruses and the Origin and Disappearance of Kuru,” Gajdusek postulated that the cause of kuru, scrapie and Creutzfeldt–Jakob disease were caused by what he termed an unconventional virus. In comparison to normal viruses, unconventional viruses had a long incubation period and did not cause an immune system response in the host. Although Gajdusek noted that there were no demonstrable nucleic acids in unconventional viruses, he did not rule out the possibility that unconventional viruses contained RNA in a smaller amount despite radiation resistance

Gajdusek was charged with child molestation in April 1996, based on incriminating entries in his personal diary and statements from a victim. He pleaded guilty in 1997 and, under a plea bargain, was sentenced to 12 months in jail. After his release in 1998, he was permitted to serve his five-year unsupervised probation in Europe. He never returned to the United States and lived in Amsterdam, spending winters in Tromsø, Norway, where the polar night around the winter solstice helped him to do more work.

Gajdusek’s treatment was denounced in October 1996 as anti-elitist and unduly harsh by controversial former Edinburgh University psychologist Chris Brand.

The documentary The Genius and the Boys by Bosse Lindquist, first shown on BBC Four on June 1, 2009, notes that “seven men testified in confidentiality about Gajdusek having had sex with them when they were boys,” that four said “the sex was untroubling” while for three of them “the sex was a shaming, abusive and a violation.” One of these boys, the son of a friend and now an adult, appears in the film. Furthermore, Gajdusek openly admits to molesting boys and his approval of incest. The film tries to understand not only Gajdusek’s sexual mores, but also his deeper motivations for science, exploration and life.

Hanya Yanagihara’s 2013 novel, The People in the Trees, is based on Gajdusek’s life, research, and child molestation conviction. The novel centers on a character named A. Norton Perina, inspired by Gajdusek, whose research is conducted on the life-extending properties of turtle meat in Micronesia.