The strain was isolated in 1937 from a patient living in East-Sumatra, Indonesia, by the staff of the Laboratory for Pathology in Medan. The isolate was considered to be a separate serovar related to djasiman (Walch-Sorgdrager, 1940). The strain appears for the first time in the list of 1959 as representing a separate serogroup (WHO, 1959). In the WHO list of 1967 the strain was placed in the Autumnalis group. However, when Dikken and Kmety (1978) reestablished the serogroup Djasiman, they included sentot in it. The TSC (1986) acepted this proposal.