CURRENT CONCEPTIONS CONCERNING THE OBJECTIVE LAWS OF A CHOLERA EPIDEMIC PROCESS: ECOLOGICAL AND MOLECULAR BIOLOGICAL ASPECTS

Abstract

Modern conceptions about the objective laws of cholera epidemic process are reviewed taking into account the peculiarities of molecular biological properties and adaptable potential of the causative agent in the endemic, epidemic and cholera safe areas. It is shown that aquatic ecosystems at the endemic territories play the significant role both in the phase of the agent reservation (when it can pass to persistent forms or remain in viable but not culturable condition) and during the pre-epidemic period. During this period the molecular genetically heterogeneity of Vibrio cholerae population in the environments gives occasion to the subsequent selection of a pandemic clone in a susceptible host. This pandemic line is low enough in water ecosystem that is proved by the data of molecular typing of clinical and aquatic V. cholerae isolates. The phase of epidemic distribution of the given type can be realized most effectively at occurring of a “fast” way of the agent dissemination from person to person at preservation of the pathogen high infectivity. The leading role in the development of epidemiological complications in the epidemic and cholera free areas belongs to importation of high infective V. cholerae clone generated in endemic foci with its subsequent accumulation in environment objects under favorable climatic, hydrological and ecological conditions. Thus, intensity of epidemic process is defined by the action both natural climatic and social factors that are limiting in the safe areas but can promote scale epidemiological complications and also the infection persistence in the epidemic regions.