Kuru is a very rare neurological disease which was documented in New Guinea through the 1960s. It is part of a group of conditions called transmissible spongiform encephalopathies (TSEs), which are characterized by damage to the brain which occurs very slowly over time. When someone eventually dies from a TSE, the brain is found to be filled with plaques of proteins and with holes, both of which would have impaired brain function during life.
People contract kuru by being exposed to prions, rogue proteins found in the brain tissue of people who have already been infected. It is believed by some that kuru in New Guinea was the result of traditional funeral practices in which people consumed the dead as part of a ritual which was intended to keep the strength and spirit of the deceased in the tribe. Women and children were commonly offered brain tissue, and they experienced much higher rates of kuru than men. It is also believed that people could be exposed to prions through open cuts and sores on their hands, which could come into contact with the protein while handling brain matter. The rapid decline in kuru rates after the government began recommending alternative funeral practices suggests that the theory that this progressive neurological disease was caused by cannibalism is correct, although some scientists continue to challenge this theory.
Once the prion enters the body, it can take years for symptoms of kuru to emerge. In people with this particular TSE, shakes and trembling are experienced; "kuru" actually means "trembling disease." The patient also experiences outbursts of laughter, explaining the alternate name of "laughing sickness," before sinking into catatonia and becoming nonresponsive. Most patients die of pneumonia or bed sores, the result of spending prolonged periods in bed. Unlike other patients with TSE, kuru patients usually do not develop dementia.
Scientists are interested in kuru and other TSEs because they provide information about prions and about they are transmitted. Variant Creutzfeld-Jakob disease, another form of TSE seen in humans, has periodically attracted media attention in various regions of the world. This form of TSE appears to be contracted through exposure to brain tissue from animals, such as squirrels and cattle, and it can also be genetic in origin.
The likelihood of contracting kuru is extremely low, as it requires intimate exposure to human brain tissue from someone who has an active infection. Other TSEs are also relatively rare among the human population.