[Epidemiology in the study of problems of health and disease (lecture)]. / Vklad épidemiologii v izuchenie problem zdorov'ia i bolezni.

Three population approaches are distinguished: statistical, clinical, epidemiological. Literature material on "etiological and epidemiological causes", "essential and sufficient causes", "internal and external etiological factors" "statistical and cause-effect relationship", etc. is summarised.

[Salmonella infection in a large general hospital]. / Sal'monelleznaia infektsiia v krupnom mnogoprofil'nom statsionare.

In this work the results of the epidemiological survey of the epidemic of salmonellosis in a large hospital with diversified specialization are given. The detailed description of morbidity dynamics with the distribution of the described cases according to the severity of the course of the infectious process, the groups of the most affected patients and the mechanism of the transmission of infection under hospital conditions is presented. This epidemic of salmonellosis is considered from the viewpoint of the theory of the self-regulation of parasitic systems. The characteristic features of nosocomial salmonellosis, detected in the course of the epidemiological survey, make it possible to determine the main trends in the prophylaxis of this infection in a large hospital.

[The hydrophobicity of Streptococcus pyogenes as a possible marker of its virulence]. / Gidrofobnost' Streptococcus pyogenes kak vozmozhnyi marker ego virulentnosti.

The hydrophobicity of 366 S. pyogenes cultures isolated from the pharynx of tonsillitis and scarlet fever patients and healthy children, as well as museum strain of type M29, was studied. The study revealed that the hydrophobicity of cultures isolated from scarlet fever patients exceeded that of cultures isolated from healthy carriers and tonsillitis patients. Among S. pyogenes cultures isolated in cases of prolonged carriership a considerable proportion of highly hydrophobic cultures was detected, which was probably indicative of an important role played by the hydrophobicity of streptococci in retaining them on the barrier epithelium. This was confirmed by the presence of correlation between the hydrophobicity of culture of S. pyogenes, type M29, and its adhesion to the fibronectin receptor and HEp-2 cells. For S. pyogenes of type M6, epidemic in the group of children under observation during the period of 1987-1988, the values characterizing its hydrophobicity were registered which significantly exceeded average hydrophobicity values. At the period of a rise in morbidity S. pyogenes cultures were characterized by significantly higher hydrophobicity. The variability of the hydrophobicity index and its relationship with the dissociation of cultures were established. The hydrophobicity index may be used as one of the virulence markers of S. pyogenes strains.

[The use of non-Euclidean metrics in epidemiological classifications]. / Ispol'zovanie neevklidovykh metrik v épidemiologicheskikh klassifikatsiiakh.

A non-Euclidean metric, stable to pollutions in sample data, for hierarchical cluster analysis in epidemiology is proposed. The simplicity of calculations permits its easy use in practice. On the basis of this metric the towns of Tula Province have been grouped according to morbidity rates in the shigellosis of Flexner and Sonne with the conjugated value of parameters.

[The production of erythrogenic toxin and the epidemic process in respiratory streptococcal infection]. / Produktsiia éritrogennogo toksina i épidemicheskii protsess respiratornoi streptokokkovoi infektsii.

The capacity of Streptococcus pyogenes, isolated from clinically healthy children in a large organized group, for producing erythrogenic toxin A, B and C was studied. The dynamics of toxin production was compared with changes in the levels of morbidity and carrier state, as well as with some characteristics of the interaction between the populations of the infective agent and the host by such values as virulence and susceptibility. Similarity in the dynamics of the parameters under study was noted. The seasonal dynamics of characteristics which determined the capacity for toxin production significantly influenced the levels and one year morbidity dynamics with respiratory streptococcal infection. The study demonstrated the information value of the characteristics of toxin production for understanding both the interval mechanisms of the epidemic process and the influence of the external ones on subsequent epidemic situation.