[The evolution of meningococcal infection in Mongolia].

On the basis of the generalization and analysis of the results of bacteriological and immunological investigations the epidemic process of meningococcal infection (MI) in Mongolia was found to undergo definite changes during the last 20 years. Group A meningococci prevailing in the etiology of MI were replaced by strains belonging to group B affecting mainly young children (aged up to 3 years). MI morbidity rate caused by group B meningococci was found to be higher in Mongolia than in other countries of the world.

[The effect of vaccination on local immunity indices; the determination of antimeningococcal antibodies in saliva].

Local immunity characteristics were studied in 130 young males; of these, 80 had been immunized with group A meningococcal vaccine. In nonstimulated saliva, collected prior to vaccination, then on days 7, 14 and 30 after vaccination, the levels of IgA antibodies to group A meningococcal group-specific polysaccharide (PS-A) were determined in the enzyme immunoassay, and secretory IgA and IgA, IgG, IgM were determined by Mancini's method. The study revealed that after the parenteral administration of group A meningococcal vaccine an increase in the concentrations of SIgA and IgA antibodies to PS-A occurred.

[The determination of antimeningococcal antibodies in the saliva of healthy people].

The determination of antibodies to the group-specific polysaccharide of group A meningococci (PS-A) in the saliva of 162 healthy persons at different seasons of the year revealed that antimeningococcal antibodies could be detected in all examines. The range of concentrations of antibodies to PS-A varied between 0.1 and 33.

[The drug sensitivity of meningococci and the characteristics of its determination].

The results obtained in the study of antibiotic and sulfamide sensitivity of 197 Neisseria meningitidis strains of groups A, B and C, isolated from the spinal fluid and blood of patients with meningococcal infection hospitalized in the 2nd Clinico-Infectious Hospital, Moscow, in 1984-1989 and studied with the use of the disc diffusion method and the method of serial dilutions of antibiotics in solid culture media, are presented. As revealed in this study, N. meningitidis strains retained their high sensitivity to penicillin and ampicillin (MIC50 = 0.

[The characteristics of suppurative meningitis morbidity caused by Streptococcus pneumoniae and Haemophilus influenza type B].

Of the 1,018 patients with purulent bacterial meningitis, hospitalized at the 2nd Clinical Infectious Hospital in Moscow during the period of 1980-1987, the diagnosis was confirmed in 54.7%; of these, meningitis of pneumococcal etiology was established in 44.8% and meningitis caused by H.

[Immunological factors in the evolution of the epidemic process in meningococcal infection].

The results obtained in 1987 in the study of the immunostructure of the population of Yaroslavl with respect to meningococcal polysaccharides, groups, A, B, C, and lipopolysaccharide are presented in comparison with earlier results obtained in 1976. The regulating role of the immunological factor in the evolution of the epidemic process of meningococcal infection has been confirmed. The level of antibodies to meningococcal polysaccharides, groups A and B, has been found to reflect the intensity of the circulation of the infective agent among the population.

[Epidemiological surveillance of meningococcal infection and the prediction of the development of an epidemic process].

The signs necessary for the prognostication of the development of the epidemic process have been formulated on the basis of the epidemiological analysis of materials obtained in the process of trials of the system for the surveillance of meningococcal infection with the use of previously established characteristics. The data on the prevalence of meningococcal infection among different age groups and on the seasonal distribution of the infection as well as on the serogroups of meningococci isolated from patients, have been shown to be of importance for prognostication.

[Antigenic affinity of meningococci and human A- and B-group erythrocytes].

The use of the modified method of isohemagglutinin adsorption by microbial antigens in experiments with the causative agent of meningococcal infection has led, for the first time, to the detection of meningococcal antigens affined to the antigens of human erythrocytes, groups A and B. The antigenic affinity of group A erythrocytes and meningococci has proved to be more pronounced in meningococcal strains isolated from the spinal fluid of patients than in cultures obtained from the nasopharynx of healthy persons. The detection of the affinity of these antigens makes it possible to explain the mechanism of differences in the susceptibility of persons with different blood groups to meningococcal infection by "antigenic mimicry".

[Etiological diagnosis of suppurative bacterial meningitis today].

As the result of laboratory examination of 2165 patients with virulent bacterial meningitides, including cases of meningococcal infection, the etiological diagnosis was confirmed in 1407 patients (65.0%), the number of cases confirmed by the laboratory examination being significantly greater among adults than among children: 67.5 +/- 1.

[Etiology of suppurative bacterial meningitis].

The results of the laboratory examination of 2034 patients with meningococcal infection and purulent meningitides, hospitalized during the period of June 1980 to October 1983, revealed that three main etiological agents were responsible for these diseases: meningococci, pneumococci and Haemophilus influenzae. The susceptibility of the patients to different etiological agents was found to depend on their age. Children aged up to 3 years constituted 75% of the patients with meningitis caused by H.

[Immunoepidemiological characteristics of the duration of a meningococcal carrier state].

The duration of meningococcal carriership in children and adults in the foci of infection and outside such foci and the immunological characteristics relating to group-specific meningococcal antigens A, C, X, Y and Z at different periods after the detection of the infective agent in the nasopharynx have been studied. Carrier state has been shown to last, on the average, 11 days. The duration of the release of meningococci from the nasopharynx has proved to be influenced by the epidemic situation in a given group.

[Criteria of the epidemiological surveillance of meningococcal infection].

The results of studies carried out with the use of the unified, specially developed methods in eight regions of the USSR are generalized. Basing on the analysis of the results, the leading role of serogroup A meningococci in the rise of morbidity is emphasized, the relation of the morbidity level to the serogroup composition of meningococci circulating among healthy population is revealed, the necessity of carrying out selective bacteriological surveys with a view to establish the serogroups of meningococci circulating among the population is shown. The expedient criteria to be used in the system of epidemiological surveillance of meningococcal infection are presented.

[Immunoepidemiological study of the meningococcal carrier state in groups of children and adolescents].

Immunoepidemiological study in groups of children of different ages was carried out. The study comprised the monthly bacteriological examination of the members of these groups and selective determination of the presence of specific meningococcal A- and C-antibodies, IgA, IgM and IgG in the blood serum, as well as the lysozyme activity of the saliva. The results thus obtained indicated that during the whole year two rises in the level of meningococcal carriership, in autumn and in spring, were registered, while the cases of meningococcal diseases were absent.

[Evaluation of the role of specific antimeningococcal antibodies in the spread of meningococcal carrier states in collectives].

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.

[Evaluation of the sanative action of rifampicin on the meningococcal carrier state].

The results of the epidemiological control experiment on the efficacy of rifampicin in sanation of meningococci carriers are presented. The preliminary study of rifampicin sensitivity of 41 freshly isolated nasopharyngeal meningococcal strains showed that the MIC of the drug for 63 per cent of the isolates was 0.04--0.

[Epidemiological and laboratory criteria in the assessment of meningococcus carrier state].

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.