The strain was isolated in Poland in 1957 from a hedgehor (Erinaceus roumanicus) by Parnas and Cybulka (1965), who described it as a new serovar named polonica. Wolff and Bohlander (1964) studied the strain and confirmed its separate serological status. This last paperappeared earlier than the publication in whiche the original findings were publiched. The description is therefore attached to the year 1964. The serovar appears for the first time in the list of 1965 (WHO, 1965).
The strain was submitted to factor analysis by Kmety(1977) and placed in the by him suggested subgroup Sejroe of serogroup Sejroe.