Relevance. In Russia every year are registred 100 or more cases of tularemia, with about 70% of them in the Central, Northwest and Siberian federal districts. Goal. Assessment of the current epidemiological situation on tularemia in the North-West Federal district (NWFD). Materials and methods. By means of a MapInfo Professional-10,5 GIS-package information on selection of cultures of the activator of a tularemia and the recorded incidence was transformed to the database on the basis of which GIS layers were created. Definition of geographical coordinates of places of isolation of cultures of a tulyaremiyny microbe from biological objects in the territory of the NWFD is carried out by means of the GoogleEarth program. Results. In 2001 - 2015 in NWFD incidence observed in all regions of the district, except Novgorod and Pskov regions. But the analysis of incidence of a tularemia allowed to reveal the sick people who infected in the territory of these regions that means there regions is endemic of tularemia. There remains a strong tendency to increase the incidence of tularemia urban population.The lack of permanent monitoring of natural eyes of tularemia in some regions of the district, does not allow to trace the development of epizootic process and to assess the intensity and magnitude of epizootics. As a result, activation of natural foci of tularemia is not noted, which increases the risk of human infection in these areas. Conclusions. Insufficient or complete lack of vaccination of people against tularemia living in areas enzootic for this infection may lead to complication of the epidemiological situation.

Relevance. Combined foci of zoonotic infections are found in all regions of the Russian Federation. A feature of combined foci is the common biocenosis for populations of pathogens of various etiologies (bacteria, viruses, parasitic infections) and the formation of natural foci by them. Aim. Epizootological study of the territory in the south of the Arkhangelsk region for the presence of combined foci of zoonotic infections (tularemia, leptospirosis and hemorrhagic fever with renal syndrome -HFRS). Materials and methods. 135 small mammals were captured and examined in the Ustyansky district of the Arkhangelsk region. Established the species composition and mixed infection among small mammals pathogens of tularemia, leptospirosis, hemorrhagic fever with renal syndrome. Results. In the south of the Arkhangelsk Region in the Ustyansky District, in 2019, for the first time, a combined natural focus of the forest type was identified and characterized. The bank vole and the common shrew are the main carriers of the causative agents of these infections. Five species of small mammals are mixed-infected with the causative agents of these infections. Infected animals with one, two or three pathogens were simultaneously detected in all studied biotopes. This indicates the presence of a combined natural focus of tularemia, leptospirosis, and HFRS. Conclusion. The existence of a combined natural focus of tularemia, leptospirosis and HFRS in middle taiga ecosystems in the south in the Ustyansky district of the Arkhangelsk region was revealed for the first time. Thus, this area can be considered enzootic for tularemia, leptospirosis and HFRS. This focus belongs to the forest type in terms of landscape and geographical characteristics. Mixed infection of small mammals suggests the possibility of simultaneous infection with pathogens of two or more infections, not only animals, but also people located on the territory of natural foci. and non-simultaneous infection of humans with tularemia, leptospirosis and HFRS in combined foci.

Relevance. Currently, the study of the combination of natural foci of zoonotic infections has become one of the urgent problems in the field of human infectious pathology, since there is a real possibility of simultaneous or not simultaneous infection of people with two or more natural focal pathogens of different etiologies and the formation of mixed infections in them. Combined lesions are characterized by territorial and morphological structure of the landscape, the presence of common reservoir hosts and types of circulating pathogens (bakterialno-bacterial, bacterial-viral, bacterial, viral, parasitic, etc.). Aims. Conduct an analysis of epizootic and epidemic activity of natural foci of tularemia, leptospirosis and hemorrhagic fever with renal syndrome (HFRS) and identify the reasons for the occurrence of mixed infections in humans. Materials and methods. To assess the activity of natural foci and to identify epizootics in populations of mouse-like rodents, the materials of long-term epizootological studies in Russia were used. A comprehensive study of rodents captured in the natural foci of the Central Federal District and the Northwestern Federal District for tularemia by serological, molecular genetic and biological methods was carried out. Statistical data on the incidence of tularemia, leptospirosis and HFRS in the territory of the Russian Federation for 2015-2020 are presented. Results. The analysis of our own research and literature data allowed us to characterize the combined foci of tularemia, leptospirosis and HFRS as bacterial-viral, according to the degree of combination in the parasitic system of common reservoir hosts, such as common, red, water voles, forest, field and house mice, insectivores. According to the level of combination of the morphological structure of the landscape, the foci belong to steppe, meadow-field, forest and floodplain-swamp, and by type these foci are characterized as infectious geographically combined. The assessment of the epizootic manifestation of foci is determined by the number of natural carriers of infections, isolation of cultures of pathogens, detection of antigen, antibodies or DNA from environmental objects, as well as the recorded incidence of people. The intensity of the circulation of infectious agents in natural foci varies in time and space depending on biotic (number of carriers, abundance of vectors, etc.) and abiotic (temperature, humidity, etc.) environmental factors. Adverse weather conditions (frosts, thaws, etc.), lack of food supply force wild rodents to migrate to populated areas, creating additional risks of human infection. To assess the epizootic manifestation of foci, the volumes of epizootic studies are of great importance, which have been reduced to a minimum and according to their results it is impossible to predict the epidemic manifestation of a particular focal area. The incidence of tularemia, leptospirosis and HFRS in humans depends on the characteristics of human-animal contacts. The epizootological situation and nosological profile in different regions have significant differences, which determines the difference in the risk of human diseases. In recent years, the number of officially registered patients with tularemia and leptospirosis in the Russian Federation is relatively small and ranges from several tens to hundreds of cases. However, the figures of officially registered patients do not reflect the real picture of the incidence of these infections, and to a greater extent indicates not the wellbeing of these nosoforms, but rather the problems of identifying (diagnosing) sick people of a particular infection. The analysis of the incidence of each case of tularemia over the past ten years has allowed to identify mixed-infected patients with pathogens of zoonotic natural focal infections. These are mainly patients with moderate-severe and severe manifestations of the disease with a primary diagnosis (acute respiratory infections, acute respiratory viral infections, purulent lymphadenitis of various localization, angina, chronic pyelonephritis, pneumonia, hepatitis, etc.). Diagnostics is aimed at determining the nosology, clinical form, severity of the condition, detection of complications and indications for treatment. For natural focal infections, information on epizootic and epidemiological examination of the focus of an infectious disease is necessary. The diagnosis is established on the basis of clinical and epidemiological data: a combination of fever and intoxication, determine the relationship of the development of the disease with work and the circumstances in which the patient was. Currently, as a result of the examination of sick people, mixed infections with natural focal infections are increasingly being registered: HFRS + tularemia; tularemia+ leptospirosis; leptospirosis + HFRS; tularemia+ borrelliosis; rickettsiosis +tularemia, etc., the presence of two pathogens of zoonotic infections was detected in the patient during successive studies. It was found that the infection of people occurred in areas enzootic for these infections. It should be remembered that a high-quality comprehensive epizootological examination of focal areas allows you to make a forecast and determine the factors of real epidemiological risk. Conclusions. In the epidemiology of any natural focal disease, it is necessary to take into account the presence of combined foci in a particular territory. Lack of experience in the diagnosis of natural focal infections of tularemia, leptospirosis and HFRS often leads to diagnostic errors, and the lack of alertness to their appearance makes it difficult to identify sporadic cases of diseases. Most nosoforms of hemorrhagic fevers lack specific prevention (HFRS among them), therefore it is necessary to strengthen measures aimed at improving the focal areas, i.e. to carry out deratization work in the most active foci near settlements and mass recreation areas of the population. Mixed infection can lead to both activation and suppression of the protective mechanisms of the human body. The exchange of information between medical and veterinary services will make it possible to better organize and carry out comprehensive measures for epizootic and epidemiological surveillance on the territory of natural foci of zoonotic infections. The formation of modern tactics of differential laboratory diagnostics will ensure the identification of mixed-infected patients with natural focal infections.

1 ФГБУ «Национальный исследовательский центр эпидемиологии и микробиологии им. Н.Ф. Гамалеи» Минздрава России, Москва 2 ФКУЗ «Противочумный центр» Роспотребнадзора, Москва Эпидемиологическая ситуация по туляремии в Дальневосточном Федеральном округе (2000-2017 гг.) Резюме Актуальность. Туляремия -природно-очаговая зоонозная инфекция, занимает существенное место в структуре инфекционной патологии человека. Заболеваемость связана с природными очагами, где имеются благоприятные условия для существования возбудителя инфекции, его циркуляции среди грызунов и других млекопитающих. Возбудитель туляремии обладает полигостальностью, поливекторностью, множественностью механизмов передачи, длительностью сохранения возбудителя во внешней среде (особенно при низких температурах), гидрофильностью, а также способностью переживать неблагоприятные условия в покоящейся (некультивируемой) форме. Туляремия -особо опасная инфекция, входит во вторую группу патогенности. Цель работы -выявление основных закономерностей функционирования и эпидемического проявления природных очагов туляремии на территории Дальневосточного федерального округа (ДВФО) на основе многолетнего мониторинга и использованием различных методов исследования. Результаты. Анализ эпизоотического состояния и эпидемического проявления природных очагов туляремии на территории ДВФО за 2000-2017 гг. свидетельствует о том, что в природных очагах этой инфекции сохраняются основные закономерности эпидемического процесса. Выявлена динамика эпизоотической активности природных очагов туляремии, подтвержденная выделением культур возбудителя и положительными серологическими находками антител и антигена, ДНК Francisella tularensis в биологических объектах. Впервые проведена ретроспективная диагностика на туляремию 249 сывороток крови людей, проживающих в районах Камчатской области и Корякского автономного округа, позволившая выявить среди местного населения лиц переболевших туляремией в разное время, что свидетельствует о наличии природных очагов этой инфекции. Установлена вероятность одновременного или последовательного заражения людей двумя, а возможно, более природно-очаговыми инфекциями в сочетанных очагах. Вывод. Анализ эпидемического проявления природных очагов туляремии на территории ДВФО в последние годы показал, что иммунизацию населения, проживающего в энзоотичных по этой инфекции районах, проводится не в полном объеме, а в некоторых субъектах она полностью отсутствует. Сокращение уровня заболеваемости людей туляремией в результате вакцинации еще не означает оздоровления самих природных очагов, потенциальная опасность которых продолжает сохраняться. Ключевые слова: природные очаги, туляремия, F. tularensis, эпидемиология, эпизоотология, микст-инфекция, вакцинопрофилактика Конфликт интересов не заявлен. AbstractRelevance Tularemia -natural focal zoonotic infection occupies an important place in the structure of human infectious pathology.The incidence is associated with natural foci, where there are favorable conditions for the existence of the pathogen, its circulation ...

Tularemia natural foci were investigated in the 15 districts of the Voronezh region. 1533 small mammals of 11 species were captured in 2011, 2014 and 2015 to identify antigen and/or DNA of tularemia pathogen. In all the studied areas there are continuous epizootic of tularemia among small mammals. In the region there are permanent natural meadow-field, floodplain- swamp and forest foci. We can assume the existence of another focus, it is a steppe type. The most active foci observed in Kashirsky, Novokhopyorsky, Petropavlosky and Ramonsky districts. The stability and activity of natural foci is maintained by alternating different biocenoses with different animals and complex pathogen exchange between foci. The most active is meadow-field and floodplain-swamp foci. Common vole is the primary carrier of the infection in the meadow-field foci during the year. In the near-water habitats of the epizootic process in strong support of field mouse and common voles. Varied species composition of small mammals provides a long time functioning and epizootic activity of natural tularemia foci. The epidemiological situation is rather calm and stable for tularemia natural foci in the Voronezh region. In the region registered a low incidence of tularemia population. There has been an increase in the incidence of the urban population. Permanent vaccination and revaccination of the population remains the main preventive anti-epidemic measures against tularemia. The results indicate the functioning and epizootic activity of tularemia natural foci in Voronezh region. It requires constant monitoring of the territory and preventive interventions, primarily vaccination of people live tularemia vaccine.