Characterisation of the Omsk collection of rickettsial strains.

North Asian tick typhus (NATT) was the first tick-borne rickettsiosis detected in Russia. To date, more than 65 000 NATT cases have been registered. Since 1954, the Omsk Institute of Natural Foci Infections has cultivated rickettsiae from ticks and clinical specimens collected in natural foci of NATT as part of the study of the epidemiology of this disease and the ecology of tick-borne rickettsiae [1]. Herein, we used gene amplification and sequencing to identify 50 strains with accuracy and thereby describe the rickettsial species endemic in NATT foci in Russia.