Epidemiological evaluation of the serological grouping of meningococci]

Use of the precipitation and hemagglutination inhibition tests to determine the serological group of 114 meningococcus strains which cannot be grouped by agglutination slide permitted to establish the serological group of 56% of the strains, this pointing to the greater diagnostic value of these tests. Nevertheless, 70% of 307 strains isolated from carriers could not be referred to any of the determinable groups (A, C, X, Y, and Z). Strains (417) isolated from the cerebrospinal fluid of patients with meningitis were grouped depending on the epidemic curve: only half of the cultures could be classified in sporadic cases, but from 80 to 100% of the strains were classified at the "peak" of the meningitis incidence rise. This rise was connected with increase of the incidence of cases caused by meningococcus, group A; at the decline these strains were eliminated, and cases due to the rarely encountered serological groups and nongrouping strains occurred. Marking meningococc by serological groups proved to be of no use for detection of epidemiological relations between the infected persons.     

Incidence of meningococcal infection in the RSFSR]

The authors present characteristics of meningococcus infection epidemic process in case of sporadic cases and under epidemic conditions (1965--1976). A scheme of epidemiological analysis suggested by the authors permitted to differentiate and to record the incidence of various clinical forms of meningococcus infection, to present data on the age, seasonal characteristics, focality, etc. Comparison of intensive morbidity indices for 10 years, both at the individual administration territories and in the Republic as a whole demonstrated morbidity level of 1.5--2.0 to be one of prognostic signs of the beginning epidemic. The main features differentiating the sporadic and epidemic morbidity periods were revealed. The presence of group diseases, a greater percentage of children among those who fell ill, and marked signs of seasonality and territorial difference characterized the period of rise caused by meningococcus of serological group A.     

Epidemiologic analysis morbidity with meningococcal infections in the USSR]

The authors present the analysis of the incidence of epidemic cerebrospinal meningitis in the USSR from 1937 to 1974, and of meningococcus infection from 1965 to 1974. A rise of the meningococcus infection incidence from 1969 to 1974 was recorded 28 years after the elevation of 1940-1942 and was 1.5 times below this latter rise. The rise in 1969-1974 was characterized by marked signs peculiar to the infection with the droplet transmission mechanism; among those who contracted the disease prevalence was seen among children aged under 14 years (63-72%). A marked affection of juveniles was noted. Three types of the dynamic of the meningococcus infection incidence in the republics located in different climatic-geographical zones of the USSR were noted: slow, gradual increase of the level, interrupted and explosive. Such character was determined in the dynamics of the seasonal elevations of morbidity. Antiepidemic measures including a complex of nonspecific measures could not be assessed as sufficiently effective. This finds reflection in the natural course of the epidemic process of the meningococcus infection which remains uncontrolled. From the patients with generalized form of the disease meningococci of group A were isolated in 80-100% of cases, from the number of those typed. The group-specific reference of the nasopharyngeal strains depended on the epidemic situation: strains of serological group A prevailed at the period of the morbidity elevation, and other serological groups (particularly of C and B) increased at its decline.     

Serologic pattern of meningococci in a focus of infection]

The authors present the results of typing of meningococci (isolated from the patients and carriers) by the sera of serological groups A, B, C, D, X, Y, and Z made at the Leningrad Institute of Vaccine and Sera. The causative agents of serological group A were most frequently isolated from the patients with the generalized forms of meningococcus infection. The percentage of detection of meningococci of serological group A was the greatest in the patients and much less in the carriers in and outside the foci of this infection. Many dissociated cultures were revealed among the strains isolated from the carriers. Sera of the Leningrad Institute of Vaccine and Sera have permitted typing of meningococci cultures belonging to various serological groups in accordance with the international classification.     

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. 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.     

Cultivation of Neisseria meningitidis serogroup A on semisynthetic liquid nutrient media]

In cultivation of meningococcus of serological group A in fluid semisynthetic medium of simple composition prepared on the basis of purified acid casein hydrolysate with profound splitting there were obtained microbial cultures with a density of 4-5 x 10(9) microbial cells per 1 ml after 20-24 hours of cultivation with shaking. Alkalinity of the medium increased (to pH 8.0-8.2 during the stationary phase) with increase of the microbial cell concentration. A study of the accumulation of group-specific thermostable polysaccharide antigen in dynamics of meningococcus cultivation on semisynthetic medium tested showed the preparations obtained by alcoholic precipitation to be colourless and to contain much antigen (by inhibition of indirect hemagglutination), particularly at the phasees of negative growth acceleration and at the stationary phase. The suggested fluid semisynthetic medium of simple composition could be used for production of diagnostic and prophylactic meningococcus preparations belonging to the serological group A.     

Characterization of the foci of meningococcal infection in closed groups of males

A total of 257 foci of meningococcal infection in groups of servicemen were selectively examined in 1982-2002. From these groups 353 patients with generalized forms of the disease underwent hospitalization. Most of the foci had a single infection, the proportion of foci with 10-40 patients was 82.6%. The meningococcal infection rate among humans in the foci was 25-37%, group A meningococci playing the leading role. In the structure of meningococcal infection generalized forms of infection constituted 16%, localized forms constituted 25% and inapparent forms (carriers)--59%. The formation of the morbidity structure was influenced by the type of the focus (with a single or multiple infection) and the character of morbidity for many years (during epidemic or at the period between epidemics). No absolute dependence of the level of meningococcal carrier state in the groups of servicemen on the appearance of the generalized forms of meningococcal infection was noted. Thus, both during epidemic and at the period between epidemics the population of meningococci, heterogeneous in its serological structure and differing in its clinical and epidemiological importance, constantly circulated with the leading role played by group A meningococci.     

The role and place of serologic research in the system of epidemiologic surveillance of meningococcal infection

The results of serological surveys, carried out with a view to the detection of capsular meningococcal polysaccharides in the passive hemagglutination (PHA) test and covering 1,289 patients with systemic meningococcal infection, 221 patients with bacteriologically confirmed meningococcal nasopharyngitis, 2,820 persons in organized groups of children and adults with different epidemiological situation (including 650 carriers) and 4,050 residents of 8 cities with different morbidity levels, were analyzed. The patients, the carriers and the members of organized groups underwent multiple surveys. As shown in this study, the confirmation of the meningococcal etiology of the systemic forms of meningococcal infection (meningitis, meningococcemia) in all cases with the exception of children under 1 year of age, as well as the determination of the groups of meningococci, could be achieved in the PHA test twice as frequently, i.e. in 60-70% of cases, as with the use of the bacteriological method. The same regularities were observed in nasopharyngitis. The conclusion was made on the possibility of using the PHA test for more exact determination of the group of meningococci, prevailing at the initial stage of diseases, this determination playing an essential role in the epidemiological surveillance. The data obtained as the result of serological surveys in organized groups may lead to conclusions on the circulation of meningococci and their group composition, thus showing the necessity of profound epidemiological study with ensuring epidemic-control measures. The selective serological study of some hundreds of donor sera is not expedient in big cities, as it provides no data on the circulation of meningococci there.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hyaluronidase in meningococcus]

A total of 204 meningococcus strains were tested for the presence of hyaluronidase, and 45.5% of the strains were found to contain it. Strains penetrating into the cerebrospinal fluid were the ones which largely produced the enzyme (in 83% of the cases). The enzyme was revealed only in 25.5% of the strains habituating on the nasopharyngeal mucosa. Hyaluronidase was mostly found in the meningococcus strains referred to the serological group A; strains of other serological groups and ungrouped strains produced the enzyme in 23.7% of the case only. There was no correlation between the capacity to form hyaluronidase and the virulence determinable in intraperitoneal infection of mice.     

The diagnostic value of a meningococcal-B erythrocyte diagnostic agent based on the group-specific polysaccharide

In this work the diagnostic value of group B meningococcal erythrocyte diagnosticum was determined. 585 blood serum samples taken from adult donors were studied: 220 samples from practically healthy persons and 365 samples from 144 patients with meningococcal infection and purulent bacterial meningitis of nonmeningococcal etiology. Group B meningococcal erythrocyte diagnosticum was found to possess serological activity and to reveal the growth of specific antibodies in the sera of patients with meningococcal infection, serologically confirmed by the isolation of group B meningococcal culture, in 100% of cases on weeks 2-3 of the disease. Diagnostic characteristics--specificity and sensitivity--for group B erythrocyte diagnosticum were, respectively, 90.2% and 63.5%. The study revealed that antibodies to several group-specific meningococcal polysaccharides in blood sera can be simultaneously determined in the passive hemagglutination test with a set of erythrocyte diagnostica, which should be taken into consideration in the clinical interpretation of serological results.     

Mass occurrence of Yersinia enterocolitica in two establishments of collective care of children.

Mass occurrence of intestinal disorders caused by Yersinia enterocolitica simultaneously in two groups of children of under-school age is reported. The question of the source of infection and the routes of transfer are discussed and the various forms pointed out which Y. e. infection may take in under-school children within the framework of an epidemic occurrence in a group of children. The fact is emphasized that the results of serological examination using the method of indirect haemagglutination may be an important guide for the orientation in the epidemiological situation and, in some cases, also in making etiological diagnosis when the proof of Y. e. by culture presents difficulties.     

Comparative evaluation of different meningococcal group-specific erythrocyte diagnostic kits in passive hemagglutination test

The comparative evaluation of the sensitivity and specificity of serogroup A, C, Y meningococcal antigenic preparations obtained by different methods was carried out by means of the passive hemagglutination test. In case of group 0 (I) human red blood cells sensitized with serogroup A and C vaccinal preparations obtained by Gotschlich's method (designated as A-1 and C-1) were used. In the other case formalin-treated sheep red blood cells sensitized with group-specific polysaccharides obtained by alcohol precipitation from the cultural fluid of group A, C and Y meningococci with subsequent heating (designated as A-2, C-2, Y) were used. Titrations with commercial immune rabbit sera showed that both variants of the antigenic preparations were similar in their specificity and sensitivity. In patients with the symptoms of meningitis the diagnostic titer was 1:40 for preparations A-1, C-1 and 1:80 for preparations A-2, C-2 and Y. The results of the examination of 164 patients (220 serum specimens) demonstrated that these preparations were of equal diagnostic value.     

Use of the oblique illumination method for characterizing N. meningitidis cultures]

The authors used the method of oblique illumination for detection of the state of the population of meningococcus cultures. In studying 48 strains there were revealed three types of fluorescence of the colonies: bright orange with a transition into greenish-light blue along the lower margin (the I type), bright light blue with a narrow orange or green upper margin (the II type) and greyish-light blue colonies (the III type). The type of fluorescence was not associated with the sero-group specificity. Populations of meningococcus cultures, depending on conditions and duration of growth on the nutrient medium could consist both of the colonies with the same type of fluorescence, and also represent a combination of colonies with a different type of fluorescence. The colonies of the I and II types of fluorescence had marked group specificity, but mutation occurred during passage and the III type of fluorescence formed with a loss of serological specificity. Continuous selection of the colonies of the I and the II types of fluorescence permitted to preserve the population with specific properties necessary for production of diagnostic and vaccine preparations for a long time.     

The choice of rational methods for determining antibodies to Yersinia enterocolitica. The agglutination reaction

Six tests suitable for the detection of antibodies to Y. enterocolitica, serovars 03 and 09, were studied. The results of the study of hyperimmune sera revealed that the agglutination test and the indirect hemagglutination test were the most promising methods and deserved efforts for their further development. Bacterial diagnostic agents were prepared from live, heat-killed and formalin-killed Yersinia cultures and tested. The titration of homologous and heterologous sera revealed no essential differences in the preparations; in the serological examination of healthy persons (102), patients with Yersinia enteral infection (150) and with other acute enteral infections (92), the results obtained with the use of the above-mentioned preparations carried the highest information content. OH diagnostic agents proved to have the highest specificity; of these, the diagnosticum obtained by treatment 0.3-0.4% formalin vas found to be the most stable and technologically effective preparation. The minimal diagnostic titer of the agglutination test for the presence of Yersinia enteral infection was established (1:60 = 1:320). This titer was determined in 73% of the patients with bacteriologically confirmed Yersinia enteral infection and only in 1% of healthy persons and patients with other acute enteral infections.     

Use of solid-phase radioimmunological analysis for the serological diagnosis of influenza

Serum samples from 91 patients with acute respiratory infections were studied in different seasons of 1981-1983. The possibility of using the solid-phase radioimmunoassay for the serological diagnosis of influenza A was shown. The use of this technique made it possible to confirm the diagnosis of influenza A (H3N2) in 43.9% of patients under examination, while in the hemagglutination inhibition test influenza was diagnosed only in 18.7% of patients. The radioimmunoassay not only essentially increases the detection rate of influenza, but also ensures the sufficient stability of this characteristic irrespective of the epidemic situation and the character of the group under examination.     

Improvement of the serological diagnosis of food poisoning]

A possibility was shown of improvement of serological diagnosis of salmonelloses with the aid of polyvalent (complex) and group salmonellosis stable formalinized erythrocytic diagnostic agents. The use of the mentioned preparations for titration of antibodies of different immunochemical nature in the sera of patients suffering from food toxicoinfections permitted to confirm the clinical diagnosis of salmonellosis in about 30% of cases.     

Basic patterns in the epidemic process of measles under conditions of massive immunization]

Observations over the measles epidemic process in Leningrad showed that the sporadic morbidity level reached in 1974--4.1 per 100 000 residents; however periodic elevation and decline of morbidity and tis seasonal variations persisted. A rise of morbidity in 1972--1973, and by preliminary data--in 1975, occurred on account of the older age groups. There was revealed no dependence of the disease incidence among the persons vaccinated on the time lapse after their vaccination. Individual batches of live measles vaccine issued in 1963--1969 were not up to the standard, this serving as one of the cases of the occurence of group incidence of the infection in some foci.     

Results of a controlled epidemiological trial of the application of placental gamma globulin in foci of meningococcal infection]

Controlled epidemiological trial was applied to the study of the use of placental gamma-globulin for prophylaxis of generalized forms of meningococcus infection in the foci (creches and kindergartens). A group of the vaccinated children (16 140) and control group (16 080) were the same age and sex. Gamma-globulin was administered in a dose of 3 ml to every other child attending creches and kindergartens not later than the 10th day after the patient's isolation. It was shown that the efficacy coefficient of gamma-globulin in the foci of meningococcus infection constituted 68% (the efficacy index was 3.2) for one month after the administration.     

The characteristics of the serological diagnosis of meningococcal infection in children in the 1st years of life

The results of clinico-immunological examination of 181 children, aged 1 month to 6 years, with generalized forms of meningococcal infection are presented. In children under observation antimeningococcal antibodies to group-specific meningococci of the main groups A, B and C were determined over the course of the disease by passive hemagglutination (PHA) test and enzyme immunoassay (EIA). The level and frequency of seroconversion were found to depend on the patient's age and the severity of the clinical course of meningococcal infection. Antibody level was found to increase simultaneously with respect to several meningococcal polysaccharides: A, B in 18.5% and A, B, C in 3.3% of cases. In the clinical interpretation of data obtained in the PHA test and EIA not only the patient's age, the form and duration of meningococcal infection, but also serotherapy should be taken into consideration, as the latter may distort the serological results.     

Ways of determination of the intensity of the epidemic process in Shigella sonnei dysentery]

Proper view on the true prevalence of Sonne dysentery characterised by polymorphous clinical picture in which many cases coursed in subclinical form could be reached only by using additional active methods for detecting the infection rate of the population. For this purpose the authors applied passive hemagglutination test which permitted to reveal the response of the organism to the antigenic stimulation in the course of two months after the sustained sickness. Over 12 000 persons were examined. According to the results of passive hemagglutination test seasonal activization of the epidemic process occurred one month earlier than it was revealed by recording of the incidence of the disease. The results of the mentioned test also showed infection rate of the population with Sonne dysentery to be as a rule greater than established by the official statistics.