V. S. Kaz’mIna

The aim of the work was to analyze the epidemiological situation on cholera in the world and in Russia and to make its forecast for 2026. Proactive epidemiological surveillance data showed that over the period of 2016–2025 there was an upward trend in cholera incidence worldwide: 5,474,013 cases were documented in 91 countries. The proportion of patients was distributed among countries as follows: Yemen (53.4 %), Afghanistan (11.7 %), Democratic Republic of the Congo (6.3 %), Nigeria (4.7 %), Somalia (3.2 %), South Sudan (2.5 %), Sudan (2.5 %), and Haiti (2.4 %). In 2025, 42 countries reported 589,571 cases and 8,140 deaths (5.1 % more than in 2024). The increase in cholera cases in 2025, compared to 2024, amounted to 5.12 %. Population migration remained the main risk-forming factor for the spread of cholera to different countries. In the Russian Federation, monitoring of labor migration was introduced with the organization of medical observation of arriving persons for seven days after arrival from cholera affected countries. As a result of monitoring surface water bodies in 2025, 50 non-toxigenic strains of Vibrio cholerae O1 circulating in the territory of the Russian Federation and belonging to different genetic lines were isolated. A decrease in the number of acute intestinal infections was noted from 13 (2024) to 5 (2025), caused by non-toxigenic V. cholerae nonO1/nonO139. Forecast for 2026: the risk of cholera importation persists due to the expected increase in the intensity of labor migration. Registration of acute intestinal infections and extra-intestinal infections caused by non-toxigenic strains of V. cholerae nonO1/nonO139 is probable. Detection of non-toxigenic strains of V. cholerae O1 and their clonal complexes circulating in water bodies will continue. Stable epidemiological situation on cholera in the Russian Federation is predicted for 2026.

The aim of the study was to analyze the data from monitoring cholera prevention measures as part of epidemiological surveillance in the constituent entities of the Russian Federation. Materials and Methods . An epidemiological and statistical analysis of the data provided by territorial bodies of the Rospotrebnadzor using developed forms was conducted through the departmental information system report.gsen.ru on a weekly basis from April to October in 2023 and 2024. Results and discussion . In light of the risk of importation and spread of cholera during the period of 2022–2024, and in accordance with the directives of the Rospotrebnadzor, enhanced monitoring for cholera was implemented across the territory of the Russian Federation. Additional sampling points were introduced at temporary accommodation centers, from wastewater before treatment, from transboundary rivers and other water objects, in cities with population over one million, in port cities, at resorts of the Azov and Black Seas, at wastewater discharge sites from infectious disease hospitals (or departments), and in areas where organized groups of labor migrants live and work. The timing of scheduled monitoring studies was changed in certain territories. The training of specialists was strengthened. The paper presents selected indicators of specialist training, the results of testing for cholera for individuals with symptoms of acute intestinal infections, and the results of monitoring studies on cholera in the territory of the Russian Federation in 2023 and 2024, including the detection of cholera vibrios O1 and non-agglutinating (NAG) vibrios depending on the nature of water use at sampling points, which indicate the presence of conditions for the possible spread of the cholera pathogen by water route in the event of infection importation in 75 % of the country’s entities.

In 2024, during routine monitoring of surface water bodies in Sochi for cholera, non-toxigenic cholera vibrios of serogroup O1 were isolated. The aim of the work was to analyze the results of the epidemiological monitoring and characterize the molecular-genetic properties of the isolated strains. Materials and methods. The work uses the data obtained as a result of an epidemiological investigation of the causes of river contamination with cholera vibrios in Sochi. Whole-genome sequencing of isolated strains was performed on the MiSeq platform (Illumina). Genetic determinants of cholera vibrio pathogenicity were identified using the BioEdit and BLASTN software. Results and discussion. It was established that the probable cause of contamination of the Matsesta river waters was the entry of non-toxigenic cholera vibrios from patients with a mild course of the disease, with an erased form of the disease or vibriocarriers. The introduction of cholera vibrios into the Agura and Mzymta rivers could have occurred due to associated groundwater, since a karst aquifer lies in the waters of all three rivers. Bioinformatics analysis showed that the isolated cultures of cholera vibrios in the waters of the Matsesta, Agura and Mzymta rivers are genetically identical, constitute a single clonal complex with strains isolated from surface water bodies of the Russian Federation, and are not imported from abroad. Vibrio cholerae O1 strains isolated from environmental objects in 2024 and cultures isolated from patients with acute intestinal infection (AII) in the Kherson Region (2024) and Krasnodar Territory (2004) belonged to the same cluster. The results indicate the presence of optimal environmental conditions for the existence of cholera vibrios in the surface water bodies of Sochi, which necessitates extensive monitoring to its maximum, provided for type I territories for epidemic manifestations of cholera, with prompt molecular-genetic study of the isolated cultures.

Objective: to analyse the possibility of Vibrio cholerae survival in surface reservoirs of the Russian Federation subjects under conditions of low water temperature, compared to the temperature optimum for the growth and reproduction of these microorganisms in environmental objects (EO).Materials and methods: official data of the reference centre for cholera monitoring on the detection of Vibrio cholerae strains in the aquatic environmental objects of the Russian Federation subjects within the framework of monitoring studies for the period from 2019 to 2024 were used. Monitoring studies were organised and conducted in accordance with the current regulatory and methodological documentation. All isolated Vibrio cholerae strains were identified by regulated bacteriological, serological, molecular-biological methods.Results: 553 strains of Vibrio cholerae O1 serogroup (three of them toxigenic) and 13013 strains of NAG-vibrios were isolated for the period from 2019 to 2024. The range of minimum water temperatures of surface reservoirs from which the first strains of Vibrio cholerae were isolated in the administrative territories of types I–III on cholera epidemic manifestations was in the range from 1 °C to 15 °C, which is lower than the temperature optimum (above +16 °C) for their growth, and indicates the possibility of survival of these microorganisms in conditions of low temperatures of water bodies, and, therefore, does not exclude the possibility of spreading infection by water in the event of a toxigenic strain entering the reservoir.Conclusions: detection of NAG vibrios and non-toxigenic strains of Vibrio cholerae O1 serogroup in the water of surface reservoirs at temperatures up to 15 °C is an indicative sign of the existence of conditions conducive to the spread of infection in case of cholera importation into the territory of the Russian Federation and indicates the expediency of an earlier start and a later end of cholera monitoring studies in Russia.

The aim of the work was to analyze the peculiarities of the cholera epidemiological situation in the world and in Russia in 2024; forecast for 2025. The results of proactive epidemiological surveillance showed a continued upward trend in cholera morbidity in the world despite of the decrease in this indicator in 2024 (762 830 cases in 42 countries) as compared to 2023 (816 235 in 47 countries). A special feature was the import of a polyantibiotic-resistant Vibrio cholerae O1 El Tor strain from Tanzania to Island Mayotte. Active labor migration to the Russian Federation (RF) from countries with unfavorable cholera situation was noted (11 686 foreigners, 88.17 % – from India). No cholera patients (vibrio carriers) were identified in RF. The features of epidemiological situation have been established: two toxigenic V. cholerae O1 strains similar to the one isolated in 2023, and one toxigenic strain of NAG, documented in RF for the first time, were detected in surface water bodies. It has been determined that the non-toxigenic V. cholerae O1 strain, which caused a case of acute intestinal infection, and waterborne O1 strains circulating in Russia belong to the same clone. For the first time, the non-toxigenic V. cholerae O139 strain was isolated from a patient with acute intestinal infection. An increase in the number of non-toxigenic O1 strains isolated from water bodies was noted (335 in 2024, 52 in 2023), mainly due to the clonal complex (250 strains, Krasnodar Territory) spread through karst waters. Diseases caused by non-toxigenic NAG vibrios V. parahaemolyticus and V. fluvialis, were detected. The forecast for 2025 covers the risks of cholera importation, including cases caused by antibiotic-resistant strains; increase in labor migration from countries with an unfavorable cholera situation; the likelihood of detecting toxigenic O1 and nonO1/nonO139 strains in the environment, an increase in the number of acute intestinal infections caused by non-toxigenic cholera and other pathogenic vibrios; possible detection of extra-intestinal infections, an increase in the number of non-toxigenic V. cholerae O1 in environmental objects. It is advisable to start monitoring studies earlier (April) and finish them later (October) in RF in 2025 in type I territories classed according to epidemic manifestations of cholera.

Objective: retrospective analysis of the results of monitoring studies of environmental water bodies in Rostov-on-Don for the presence of V. cholerae for the period from 1989 to 2023 at stationary sampling points assigned to the Rostov-on-Don Anti-Plague Institute of Rospotrebnadzor, identification of trends and features of the dynamics of isolation and biological properties isolated strains. Materials and methods: in the period from 1989 to 2023, 4362 samples from aquatic ecosystems were examined. The organization and conduct of research was carried out in accordance with regulatory and methodological documents (SanPiN 3.3686-21, MUK 4.2.3745- 22, MUK 4.2.3746-22). Sequencing of isolated strains was performed on the MiSeq (Illumina) platform. Results: during the analyzed period, V. cholerae strains were found in all studied reservoirs of the Rostov-on-Don: in the Don, Temernik and Dead Donets rivers, mainly in July and August. Of the 122 isolated strains, 8 are epidemiologically significant (toxigenic strains) and 114 are nontoxigenic. The largest number of strains was isolated in 2022 — 21 strains. V. cholerae strains O1 (119 strains) and O139 (3) of serogroups, biovar classic and El Tor (Ogawa, Inaba and Gikoshima serovars) were found. Conclusions: epidemiological risks of the introduction of the cholerae pathogen from endemic countries, as well as from neighboring countries, in cases of complications of the epidemic of this infection, remain. In the surface reservoirs of the Rostov-on-Don, there are favorable conditions for the circulation of V. cholerae and the risk of spreading infection by water, in case of contamination by the cholerae pathogen of aquatic ecosystems.