Outbreaks of tularemia in Russia (1997–2023)

Relevance. Currently, much attention is paid worldwide to diseases transmitted by vectors (bites of ticks, mosquitoes and horseflies). In our country, at least nine pathogens of zoonotic infections transmitted by this route are registered: tularemia, borreliosis, tickborne encephalitis, anaplasmosis, rickettsiosis, Q fever, babesiosis, bartonellosis and ehrlichiosis. In Russia, outbreaks of tularemia associated with the transmission of infection through bites of blood-sucking arthropods have increased, and waterborne and trench epidemic outbreaks have also been registered. Waterborne outbreaks are associated with the use of water contaminated with corpses or excrements from sick rodents. Trench outbreaks are associated with the mass settlement of military structures by rodents, in whose populations epizootics occur.
Goal Target. Determination of the epidemiological type of outbreak morbidity and the possibility of its elimination. Materials and methods. The materials were statistical data of Rospotrebnadzor on the incidence of tularemia, the volume of vaccination against this infection. Retrospective data on morbidity and epizootological studies from the archives of the Gamaleya National Research Center for Epidemiology and Microbiology of the Ministry of Health of the Russian Federation for 1997–2023, 375 cards of epidemiological investigations of tularemia cases were used. Reports of epizootological surveys of focal areas of the regions of the Russian Federation were analyzed.
Results and discussion. In the territory of the Federal Districts of Russia from 1997 to 2023 inclusive, 61 epidemic outbreaks of tularemia from 10 to 955 cases were registered, including 52 transmissible in the Central Federal District (13), Northwestern Federal District (18), Ural Federal District (5), Siberian Federal District (9), Volga Federal District (6) and Far Eastern Federal District (1). The total number of cases during the outbreaks was 3261 patients with tularemia, of which: 2754 cases of diseases from bites of blood-sucking arthropods (transmissive type of disease), 254 people fell ill after drinking raw water (water type of disease), 253 people fell ill while in trenches (trenches), where there was a large accumulation of rodents (trench type of disease). Bubonic and ulcerative-bubonic clinical forms of tularemia are typical for transmission through horseflies and mosquitoes, and when an insect gets into the eye, the ocular-bubonic form. Waterborne outbreaks of tularemia occur when drinking or washing with water. The main clinical forms of this type of disease are angina-bubonic, abdominal and ocular-bubonic, sometimes mixed - abdominal + angina. In the trench type of infection, pulmonary with bronchitis and pneumonic variants (thoracic), angina-bubonic (anginal-glandular) and abdominal (gastrointestinal) clinical forms of tularemia prevailed. The cause of the outbreak was a combination of natural factors, lack of immunity in the population and insufficient awareness of the etiological diagnosis of the infection. With the cessation of human morbidity, the natural focus of tularemia does not cease to exist, and with a decrease in the number of vaccinated, and therefore susceptible to the pathogen, a threat of a new outbreak arises.
Conclusions. In order to ensure epidemiological well-being in terms of tularemia, it is necessary to maintain the level of vaccination and revaccination within 2.5–3 million per year of contingents subject to vaccination, taking into account the degree of epizootic activity of natural foci. Epidemic outbreaks of tularemia may occur against the background of a significant decrease in the volume of vaccination of the population living in areas enzootic for this infection. Tularemia is characterized by polymorphism of clinical manifestations, therefore, a carefully collected epidemiological history is of great importance for the diagnosis of this infection. It is necessary to conduct explanatory work on preventive measures among the population living in areas endemic for tularemia in connection with multiple refusals of vaccination against tularemia. It is necessary to carry out measures to improve the sanitary and epidemiological literacy of doctors regarding tularemia infection.

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