title: [Historical origin and evolution of the agents of infectious diseases].
abstract: Data on the establishment and further evolution of the causative agents of human infectious diseases were systematized. Saprophytes proved to be the initial stage of this evolution for all the parasitic species. It was demonstrated by concrete examples that evolution of parasitism was the result of an interaction of many factors (the mechanism of transmission of the causative agents, the immunity formation in the population, hereditary resistance, etc.) and not only the sequence of a unilateral action of the transmission mechanism. The author considers that some properties of the causative agents of the infecticus diseases of man (spore formation, the capacity to reproduction on the objects of the external environment) were not newly acquired in the process of the parasitic species formation, but atavistic signs which persisted from saprophytic ancestors. The dialectics of progressive and regressive processes in the acqisition of the parasitic properties by saprophytes is considered.
mesh_terms: D005075:Biological Evolution; D006801:Humans; D007239:Infections / Q000382:microbiology* / Q000635:transmission; D010272:Parasitic Diseases / Q000382:microbiology
vernacular_title: K voprosu ob istoricheskom proiskhozhdenii i évoliutsii vozbuditeleĭ infektsionnykh bolezneĭ