Kuru is a subacute
neurodegenerative disease presenting with
limb ataxia,
dysarthria, and a shivering
tremor. The disease progress to complete motor and mental incapacity and death within 6 to 24 months. Neuropathologically, a typical pattern of neuronal loss, astrocytic and microglial proliferation, characteristic "
kuru-type"
amyloid plaques, and PrP deposits in the cerebral cortex and cerebellum are observed.
Kuru is the prototype of a group of human
transmissible spongiform encephalopathies (TSEs), or "
prion" diseases, that include hereditary, sporadic and infectious forms. The latest member of this group, the
variant Creutzfeldt-Jakob disease (vCJD), linked to transmission of
bovine spongiform encephalopathy (BSE) to humans, shows features similar to
kuru.
Kuru has emerged at the beginning of the 1900s in a small indigenous population of New-Guinean Eastern Highlands, reached epidemic proportions in the mid-1950s and disappeared progressively in the latter half of the century to complete absence at the end of the 1990s. Early studies made
infection, the first etiologic assumption, seem unlikely and led to a hypothesis that
kuru might be a genetically determined or genetically mediated illness. After transmissibility of
kuru had been discovered and all major epidemiologic phenomena adequately explained by the spread of an infectious agent with long incubation period through the practice of cannibalism, the pattern of occurrence still continued to suggest a role for
genetic predisposition. Recent studies indicate that individuals homozygous for
Methionine at a polymorphic position 129 of the
prion protein were preferentially affected during the
kuru epidemic. The carriers of the alternative 129Met/Val and 129Val/Val genotypes had a longer incubation period and thus developed disease at a later age and at a later stage of the epidemic. Observations made during the
kuru epidemic are helpful in the understanding of the current vCJD outbreak, and vice versa clinical and experimental data accumulated in studies of other TSE disorders contribute to better understanding of the documented
kuru phenomena.