The strain Mankarso was isolated in Sumatra, Indonesia, in 1938 from a patient suffering from leptospirosis (Wolff, 1953). It first appeared as a separate serovar named mankarso in Wolff and Broom's list (1954). In his "Laboratory Diagnosis of Leptospirosis" (1954), page 82, Wolf states that "the strain Mankarso shows sereologic affinity to L. icterohaemorrhagiae and L. naam, but absorption tests have revealed slight differences in antigenic constitution". The strain was submitted to factor analysis (Kmety, 1967), which proved its separate status.