Main problems of system of epidemiologic control for cholera active in Russian Federation, as well as laboratory diagnostics and vaccine prophylaxis of this especially dangerous infection, that had emerged in the contemporary period of the ongoing 7th pandemic of cholera, are discussed. Features of the genome of natural strains of Vibrio cholerae of El Tor biovar, that possess a poten- tial epidemic threat, as well as problems, that have emerged during isolation of these strains from samples of water of surface water bodies during their monitoring, are also examined. The main direction of enhancement of the system of epidemiologic control for cholera consist in develop- ment of a new algorithm of differentiation of administrative territories of Russian Federation by types of epidemic manifestations, as well as optimization of monitoring of environment objects. Integration of modern highly informative technologies into practice, as well as development of new generation diagnostic preparations based on DNA-chips and immunechips is necessary to increase effectiveness of the conducted operative and retrospective diagnostics in the contemporary period. Creation of national cholera vaccine, ensuring simultaneous protection from cholera causative agents of both O1 and O139 serogroups, is also required.
Results of analysis of cholera outbreak during which V. cholerae O1 biovar El-Tor ctxAB- tcpA+ was isolated from 2 patients and 30 carriers are presented. Epidemic was caused by contamination of water source and water route of transmission. Strains identical to ones detected in humans were isolated from water of surface well in zone of water intake. Genome and VNTR-analysis of ctxAB- tcpA+ vibrios that caused outbreak in Rostov region in 2005 showed that they differed from ctxAB- tcpA- and ctxAB- tcpA+ vibrios isolated previously during and beyond of outbreaks from patients, carriers and environment and formed separate group with certain genotype. These results confirms conclusions of epidemiological analysis about imported cause of recent outbreak.
Data on emergent epidemiological analysis of the cholera outbreak in Kazan are presented. A version of the cholera focus emergence was confirmed, namely water route of transmission as a result of bathing in a water reservoir where sewage waters had penetrated. The outbreak had local and acute character. The complex of cholera control interventions aimed at localization and liquidation of the focus proved to be effective.
The analysis of the data on the isolation of V. cholerae from different ecological systems indicates that V. eltor do not constantly inhibit the rivers and sea at the territory under control. Hemolytically active V. cholerae without the vct gene, found to be faintly virulent and avirulent when studied on suckling rabbits used as a model and when evaluated by the complex method, show no tendency towards epidemic spread in the presence of conditions for the realization of the transmission of vibrios by the water route.
The virulence of V. cholerae isolated on the territory of Russia and other CIS countries from environmental objects and from humans in different epidemic situations during the period of 1987-1991 was studied. The analysis of the data obtained in this study revealed that intensive epidemic complications were linked with the realization of the pathogenic properties of strains, characterized by the presence of the ctx gene and the absence of hemolytic activity. As a rule, in single cases or in isolated group cases of cholera V. cholerae hemolysin-negative strains without the cholera toxin gene were isolated.