Hydrobionts as reservoir hosts for infectious agents of bacterial sapronoses

Data on parasitism of the infectious agents of sapronoses in hydrobionts (protozoans, crustaceans, worms, mollusks, echinoderms, and fishes) are considered from the population-ecological viewpoint. The symbiotic relationships between populations of pathogenic bacteria and protozoans are of the host-parasite type. An ultrastructural analysis demonstrates that phagocytosis is incomplete both in planktonic forms and in biofilms formed by bacteria and protozoa. This provides for long-term survival of infectious agents in the environment. The migration of Yersinia pseudotuberculosis along trophic chains from the lowest to the highest level has been simulated experimentally. The long-term survival of pathogenic bacteria in aquatic animals and the ability of bacteria to migrate along trophic chains, reaching soil animals and humans, provide evidence that comprehensive studies on the routes of circulation of pathogens in natural ecosystems are highly relevant from the ecological and epidemiological viewpoints.