Researchers from the Laboratory of Zooanthroponotic Infections at St. Petersburg Pasteur Institute (I.A. Karmokov, O.A. Freilichman, R.R. Baimova, D.I. Grechishkina, G.A. Lunina, I.S. Lyzenko, E.G. Ryabiko, and N.K. Tokarevich), together with colleagues from the Laboratory of Molecular Genetic Monitoring (T.V. Arbuzova and A.V. Bachevskaya), as well as with colleagues from scientific and practical institutions in the Northwestern Federal District (NWFD), published the results of a study examining the prevalence of tick-borne spotted fever rickettsiae in ixodid ticks collected in northwestern Russia. The results of the study, which covered eight regions (the Arkhangelsk, Kaliningrad, Leningrad, Novgorod, Pskov, and Vologda regions, as well as the Republic of Karelia and St. Petersburg) and more than 4,500 ticks, were published in the journal Tropical Medicine and Infectious Disease (MDPI).
Five species of tick-borne spotted fever rickettsia were found to circulate in natural foci of the Northwestern Federal District: Rickettsia helvetica, Rickettsia conorii subsp. raoultii, Candidatus Rickettsia tarasevichiae, Rickettsia monacensis, and Rickettsia felis. Rickettsia felis was identified for the first time in Russia, in ticks collected from vegetation, and Rickettsia monacensis in the Northwestern Federal District. The study not only updated data on the species diversity of rickettsiae in ticks in this area but also identified significant changes in their infection rates compared to previously published studies.
Of particular interest was the detection of a mixed infection – the simultaneous detection of Rickettsia helvetica and Candidatus Rickettsia tarasevichiae – in two Ixodes persulcatus samples collected in the Novgorod Region. Attachment of such a tick to a person, followed by infection with these two rickettsia species, could potentially lead to the development of more severe forms of rickettsiosis.
The study's results can serve as a basis for improving epidemiological surveillance and prevention of tick-borne rickettsiosis in the Northwestern Federal District.