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The aim of the study was to determine the prevalence of leptospiroses and hemorrhagic fever with renal syndrome (HFRS) among residents of some administrative districts of the Leningrad Region. Materials and methods. 958 blood serum samples of conventionally healthy individuals living in the following territories of the Leningrad Region: Boksitogorsky, Volosovsky, Vyborgsky, Kingiseppsky, Lodeynopolsky, Luzhsky, Podporozhsky, Priozersky, Slantsevsky and Tikhvinsky districts – were analyzed by enzyme immunoassay. The retrospective epidemiological analysis of the incidence of leptospirosis and HFRS in the population of the Leningrad Region in 2011–2020 was carried out based on the data from the Rospotrebnadzor Administration and Forms No. 2 “Information on infectious and parasitic diseases”. Results and discussion. All in all, 54 cases of leptospirosis and 104 cases of HFRS were registered in the Leningrad Region in 2011–2020. The long-term average annual incidence rate (LTAAIR) for leptospirosis was 0.32. In Boksitogorsky, Vyborgsky, Lodeynopolsky, Podporozhsky and Slantsevsky districts, cases of leptospirosis were not recorded, but IgG-antibodies to Leptospira interrogans were detected in residents of those areas. The LTAAIR for HFRS was 0.63. There are no registered cases of HFRS in the Kingiseppsky, Podporozhsky, and Slantsevsky districts. IgG-antibodies to Orthohantavirus were detected in volunteers in all surveyed areas. The detection of specific antibodies in the blood sera of conventionally healthy people living in the Leningrad Region indicates contact of the population with pathogens of leptospirosis and HFRS. The lack of registered morbidity in some areas is probably due to their hypo-diagnosis, as evidenced by the detection of antibodies to the pathogens of these infections in people living in the corresponding territories.

Introduction. Knowledge about tick-borne disease (TBD) distribution is necessary to improve prevention, whereas detection of human serum IgG antibodies against relevant pathogens is a method for monitoring TBD prevalence in local population. The study objective was to estimate seroprevalence of IgG antibodies against tick-borne encephalitis virus (TBEV), Borrelia burgdorferi sensu lato, Coxiella burnetii, Anaplasma phagocytophilum, and Ehrlichia chaffeensis/E. muris in healthy residents from the five territories of the Northwestern Federal District of the Russian Federation (Arkhangelsk Oblast, Leningrad Oblast, Pskov Oblast, the Republic of Komi and the Republic of Karelia). Materials and methods. In 20172019, a total of 1244 serum samples from healthy residents, not vaccinated against TBDs or other flavivirus-caused infections was studied by ELISA. Results. 21.7% of the sera samples contained IgG antibodies against a single TBD pathogen, whereas 2.1% showed signs of coinfection with two or more pathogens. The most common were IgG antibodies against TBEV (5 territories, 12.2%), followed by Borrelia burgdorferi sensu lato (5 territories, 3.5%), C. burnetii (4 territories, 2.9%), Anaplasma phagoсytophilum (3 territories, 1.6%), E. chaffeensis/E. muris (5 territories, 1.5%). The IgG antibodies were more common in men (55.2%) than in women (44.8%), being found virtually evenly in age-independent manner (from juniors under 18 to seniors over 60). Conclusion. The results of this first comprehensive serosurveillance study in the Northwestern Federal District of the Russian Federation assessing serum IgG antibodies against tick-borne diseases indicate a wide distribution of such pathogens. Moreover, infections caused by C. burnetii, Anaplasma phagocytophilum, and Ehrlichia chaffeensis/E. muris might be highly underdiagnosed.

Introduction. Vaccination contributed to reduce the incidence of acute hepatitis B in the territories of the North-West Russia. The urgency of this problem remains due to the high incidence of chronic hepatitis B. This accounted for the need to develop a hepatitis B elimination program in the district discussed that was approved in 2013 by the head of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing. Objective is to characterize the results of the program for the elimination of acute hepatitis B virus implemented in the North-Western Federal District. Materials and methods. The 2010–2020 incidence rate of acute and chronic hepatitis B virus (HBV) infection in the regions of the North-West Russia was carried out. To determine HBV genotypes and subgenotypes, 160 blood plasma samples from patients with acute hepatitis B were studied using molecular genetic methods (PCR, sequencing). The prevalence of latent hepatitis B in various population groups was assessed. The 2016–2020 hepatitis B vaccination coverage and relevant serological monitoring in adults was carried out. Results. While implementing the program, it was found that the incidence rate of acute hepatitis B in the district decreased by 4.5-fold, revealing in 2020 no cases of the disease in 5 regions, with incidence rate in the 6 subfederal units being lower than 1.0 per 100,000 population. Moreover, the incidence rate for chronic hepatitis B decreased by 2.6 times. The 2020 vaccination coverage of children under 17 and adults in all territories comprised more than 95% and 90%, respectively. In addition, it was shown the circulation of genotypes D and A of hepatitis B virus is dominated by genotype D (91.8%), subgenotype D2 (47.8%). The prevalence of latent hepatitis B among migrants was 6.5%, pregnant women — 4.9%, hemodialysis patients — 1.7%. Conclusion. Implementation of the program on elimination of acute viral hepatitis B in the territory of the North-West Russia contributed to raise in the vaccination coverage in adult population and lowered incidence rate of acute and chronic HBV infection.