the incidence of kuru increased in the 1940s and ‘50s and mortality rate began to approach close to 35/1000 in a population of 12000 fore people. the mortality rate distorted the female:male ratio, which reached 1:2, or even 1:3 among south fore. the prevalence of the kuru epidemic has been on a steady decline since the 1950s, but has linked into the 21st century due its incubation period which can last as long as 50 years.