[Statistical indices in medicine and epidemiology and their classification].

Mathematical statistics deals with abstract notions, while medicine solves complicated and many-sided problems. For this reason medical statistics faces some moot points in the interpretation of a number of notions and the classification of statistical indices. In the present article the definition of variables and statistical indices is formulated and their characterization is given. An attempt is made to provide the systematization and natural classification of the latter. Statistical indices are defined as the characteristics of statistical totalities. To classify statistical indices, the most essential signs are used: the character of a variable (external relations), the trend of study (internal content), the form of expression (calculation), derived indices and characteristics (comparison and the results of analysis).

[Morbidity: terminology, mechanisms of formation and classification]. / Zabolevaemost': terminologiia, mekhanizmy formirovaniia i klassifikatsiia.

In the 70-ies of the last century the evolution of the epidemic process doctrine resulted in developing population approach to morbidity analysis, in addition to the traditional focal approach. On the one hand, this led to the discussion on the possibility of applying such notion to non-infectious diseases and, on the other hand, to the discussion on the mechanisms of the development and formation of different manifestations in infectious diseases. In both cases the discussion was centered on the phenomenon of morbidity. The present article deals with the nature of morbidity as a phenomenon and the acceptability of general scientific approaches in the interpretation of seasonal and cyclic character of morbidity from the viewpoint of the wave process in an open system. On the basis of the data presented in this work the terms used in epidemiology in considering manifestations of the epidemic process are discussed. The improved classification of morbidity by qualitative and quantitative signs for infectious diseases is proposed.

[The manifestations of an epidemic process in a respiratory streptococcal infection among ships' crews under commercial sailing conditions]. / Proiavleniia épidemicheskogo protsessa respiratornoi streptokokkovoi infektsii sredi ékipazhei sudov v usloviiakh promyslovogo reisa.

Morbidity in respiratory streptococcal infection in 6 ships of the State Fishery Amalgamation "Dal'ryba" during 8 voyages was analyzed. During voyages morbidity rate is determined by sporadic cases, seasonal rises at the time of the voyage and epidemic outbreaks. Spring and summer months constitute the period of risk for seasonal morbidity rises during voyages and epidemic outbreaks at the time of the formation of the crew. The minimal size of the crew in which the activation of the epidemic process took place was 350 persons. In lesser crews (250-300 persons) seasonal rises in morbidity were observed only in the presence of frequent and intensive change-over of crew members.

[Streptococcal respiratory infection in large organized children's collectives and experience in optimizing its prevention]. / Respiratornaia streptokokkovaia infektsiia v krupnykh organizovannykh detskikh kollektivakh i opyt optimizatsii ee profilaktiki.

Epidemiological analysis of the manifestations of respiratory streptococcal infection in the all-year-round pioneer camp "Ocean" over 1984-1990 and in similar large organized groups of children revealed some common regularities manifested as consecutively repeating morbidity rises in acute respiratory diseases, tonsillitis, scarlet fever over a year (rotations 1-3 and 9). Time course of the disease incidence over each rotation (month) had a specific pattern as well. Trials of our newly developed system of prevention and treatment with tomicid showed its high effectiveness, which manifested by a drop in the morbidity level and changes in the structure and dynamics of respiratory streptococcal infection.

[A comprehensive evaluation of the biological properties of the causative agents of typhoid fever isolated from patients and carriers]. / Kompleksnaia otsenka biologicheskikh svoistv vozbuditelei briushnogo tifa, vydelennykh ot bol'nykh i nositelei.

The biological properties of 106 S. typhi cultures were studied; of these, 59 cultures were isolated from 45 chronic carriers and 47 cultures, from 23 typhoid fever patients. According to the degree of their virulence (CPD50 in the continuous cell-line culture Hep-2), the strains isolated from the patients were more virulent than those isolated from the chronic carriers. The mean value of lg CPD50 was 5.76 +/- 0.04 for the patients and 6.86 +/- 0.03 for the chronic carriers. The strains isolated from the patients showed greater variability in the degree of their virulence. The study of the plasmid spectrum showed that 9.4 +/- 5.6% of the strains contained plasmids. From the patients plasmid-containing strains were isolated more frequently than from the carriers (14.9 +/- 2.5% and 5.1 +/- 2.9%). Multiresistance to antibiotics in combination with the presence of plasmids was detected in 6 strains isolated from the typhoid patients with morbidity having the character of outbreaks.

[The manifestations of an epidemic process of typhoid infection in Moscow]. / Proiavleniia épidemicheskogo protsessa briushnotifoznoi infektsii v Moskve.

The work deals with the results of typhoid morbidity in Moscow for the period of 1980-1988. The morbidity rate varied from 0.98 to 0.17 cases per 100,000 of population with a tendency towards decrease. In the structure of morbidity local cases accounted for 46.8% and cases of infection contacted outside Moscow accounted for 53.2%. The morbidity level was low throughout the whole territory, only in two districts morbidity rate was significantly higher (P = 95%) than the average morbidity rate in the whole of the city. In the group of local cases morbidity had no pronounced seasonal character, in contrast to cases due to infection contacted outside the city which were mostly registered in summer and autumn. Persons aged 21-30 years were found to be the most affected age group. The general factors, and not the contact route, are supposed to play the main role in the realization of the mechanism of infection transfer. Under modern conditions, some manifestations of the epidemic process of typhoid infection can be detected only at the level of the whole city, or even the whole country.