The strain was isolated in 1958 by Janev from a patient in Bulgaria. Badudieri and Mateev (1961) studied the strain and described it as a 'subserotype' of sejroe named balcanica. The strain appears for the first time as such in the list of 1965 (WHO, 1965). AFter the abolition of the taxon 'subserotype' it appears in the serovar list of 1967 (WHO, 1967) as a separate serovar within the Hebdomadis serogroup.
The strain was submitted to factor analysis by Kmety (1977), who placed it as a separate serovar in the subgroup Sejroe of the newly established seroroup Sejroe.