[Evaluation of the role of specific antimeningococcal antibodies in the spread of meningococcal carrier states in collectives]. / Otsenka roli spetsificheskikh antimeningokokkovykh antitel v rasprostranenii meningokokkovogo nositel'stva v kollektivakh.

The results of serological, bacteriological and epidemiological studies carried out in populations with different epidemic pattern of meningococcal infection are presented. A-group specific antibody was found to have the leading role in the intensity of the spread of meningococcal infection in the populations. The presence of antibody to this antigen in 16.7% of serum samples inhibited dissemination of meningococci in the populations. Simultaneously with an increase in the herd immunity level to 34.8% the attenuation of the active meningococcal dissemination cycle was observed. Meningococci isolated in the populations with different epidemic patterns of meningococcal infection were shown to have different ecological properties.

[Epidemiological and laboratory criteria in the assessment of meningococcus carrier state]. / Epidemiologicheskie i laboratornye kriterii v otsenke meningokokkovogo nositel'stva

A study was made of the duration of meningococcus carrier state, immunological indices and group-specific properties of meningococci isolated from them. The periods of meningococcus discharge were studied in 738 persons. Three categories of the carrier state were revealed: a single discharge (67% of the carriers), of average duration (up to 4 weeks), and prolonged. Greater indices of group-specific antibodies (in the passive hemagglutination test) were revealed in the carriers with prolonged presence of meningococci in the nasopharynx. Dynamics of immunological indices and periods of the carrier state formation in the foci of infection permitted to characterize the prolonged carrier state as a latent form of meningococcus infection. A study of the group-specific properties in 1845 strains and comparison of the group-specific pattern of the circulating strains with the epidemic situation indicated that meningococci of group A were not only epidemic, but also more virulent.

[Role of meningococcal carrier state in formation of the immunologic structure of a collective with regard to that agent]. / Izuchenie roli nositel'stva meningokokkov v formirovanii immunologicheskoi struktury kollektiva v otnoshenii étogo vozbuditelia

The authors present the results of the immuno-epidemiological studies of two collective bodies -- over 2000 persons in all -- equal by age composition and physical load, who were under the same sanitary-hygienic conditions. Observations were carried out from the time of formation of these collective bodies in November and were continued for a period of 6 months; they differed by the epidemic situation in respect to the meningococcus infection, i.e. cases of this disease and carriers were present in the first, and carriers only in the second group. The collective bodies were subjected to complete bacteriological examination (at the time of formation and in 3 and 6 months); blood was studied for the presence of antibodies to the complex meningococcus antigens of groups A, B and C (in the passive hemagglutination test.) There proved to be a marked increase in the percentage of positive tests with the A- and C-antibodies in both collective bodies and an increase in the number of positive tests with B-antibodies only in the collective body with no meningococcus cases. Since in the first collective body the percentage of generalized meningococcus infection cases was insignificant (about 0.85%) and there were no cases in the second collective body, a conclusion could be drawn that changes in the immunological indices among persons in these groups were caused by carrier state. Thus, the effect of meningococcus carrier state on the formation of immunological indices of collective bodies was revealed.