Results of Epidemiological Monitoring of Cholera Vibrios, Serogroup O1 in Surface Water Bodies of Sochi in 2024

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.

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