Kuru kept killing decades after its cause had already stopped
The Fore people of Papua New Guinea had largely abandoned funerary cannibalism by around 1960, before anyone linked it to the trembling disease killing their women and children. Yet kuru's incubation can exceed 50 years, so deaths continued for half a century, the last known one in 2009.
Kuru was a fatal prion disease of the nervous system. Its name comes from a Fore word meaning to shake, and it was also called laughing sickness because patients burst into uncontrolled laughter. Patrol officers first reported it in the Eastern Highlands in the early 1950s; Arthur Carey used the word kuru in a 1951 report, while another officer dismissed it as a psychosomatic response to sorcery. The Fore themselves blamed witchcraft or ghosts.
In 1961 the researcher Michael Alpers and anthropologist Shirley Lindenbaum traced the epidemic to mortuary feasts in which relatives ate the dead to return their life force to the hamlet. Women and children ate the brain, where prions concentrate, while men, who believed human flesh weakened them for battle, mostly took muscle. At its peak the disease struck women and children eight to nine times more often than men, and around 1957 about 200 people died each year. The outbreak probably began early in the 1900s with one person who developed sporadic Creutzfeldt–Jakob disease.
The agent is a misfolded version of an ordinary brain protein. The healthy form is rich in alpha helices; the rogue form has the same amino acids but folds into beta sheets, clumps together and resists enzymes. It appears to convert normal copies on contact, setting off a chain reaction. Once symptoms begin, illness lasts about a year and passes through three stages, from unsteady walking to needing support to being unable to sit up or swallow. Brain studies show shrunken, moth-eaten neurons resembling those in Creutzfeldt–Jakob disease.
The epidemic also left a genetic trace. In 2009 Medical Research Council scientists, after studying more than 3,000 people since 1996, found a variant called G127V that gives strong resistance to kuru. It occurs almost only where the epidemic raged and seems to have arisen about 10 generations ago, and researchers hope it may shed light on other prion and neurodegenerative diseases.
Source: Kuru (disease)
