During January 1957, a number of human cases of fever were reported at the Primary Health Center at Ulvi in the Shimoga district of Karnataka State. Since the first record of the disease in 1957, epidemics of Kyasanur Forest Disease (KFD) have occurred every year. The number of cases average about 400 to 500/year, with the low incidence in 1961 and highest incidence in 1976, 1977, and 1983. However, the villagers bear this with a considerable degree of fortitude. In 1966, the bamboo forests bloomed in the endemic area of KFD. The incubation period of KFD in man is estimated to be about 2 to 7 days. The onset is sudden, with chills followed by severe frontal headache. The onset is so sudden that most patients can accurately state the time when they fell ill. Fever soon follows headache and rapidly rises to 104°F.