Circulation of the causative agent of diphtheria in immune collectives

Prolonged observations on the spread of toxigenic C. diphtheriae carriership, made during a school year in 12 groups of immune children (3809 children), showed that the penetration of diphtherial infection could give rise to the outbreak of bacterial carriership, its level being as high as 20.9-35.1% of the total number of children in the group. The spread of bacterial carriership occurred during the first months after the penetration of the infection, achieving its peak, then followed the subsidence of the infection in the focus. Though some children in the group persistently released C. diphtheriae, almost no new cases of carriership were registered in spring. The highest spread of carriership (55.6-73%) was revealed in the first forms of boarding schools despite a higher level of antitoxic immunity in these children. Cases of the spontaneous cessation of carriership were observed. The spread and subsidence of carriership were determined by the presence or absence of a susceptible contingent. Tests on guinea pigs, carried out in the course of this study to determine the toxigenicity of C. diphtheriae, showed its variability.     

The epidemic process of an acute streptococcal respiratory infection in large organized collectives of children

The study of the specific features of the development of the epidemic process of scarlet fever, tonsillitis, and acute respiratory diseases (ARD) in two large organized groups of children revealed the presence of some differences which depended on the character of prophylactic measures taken in these groups. Thus, in the absence of prophylaxis with bicillin a pronounced increase in the level of carriership, accompanied by an increase in the infective capacity of carriers, was noted. This resulted in a high level and unfavorable dynamics of morbidity in scarlet fever, tonsillitis, and ARD. On the contrary, the use of prophylaxis with bicillin ensured the stability of the level of carriership, while the infective capacity of carriers was not pronounced. At the same time a rise in ARD morbidity was insignificant, and morbidity in scarlet fever and tonsillitis was reduced to nil.     

Hepatitis A foci in children's collectives studied by using clinico-biochemical, virological and serological diagnostic methods

In 4 foci of hepatitis A (HA) at children's institutions in Moscow 218 children and 30 staff members were examined. Simultaneously with clinico-biochemical studies, specific IgM and IgG in the blood and hepatitis A virus (HAV) antigen in feces were determined by radioimmunoassay. Different forms of HA were detected in 29.1% of children in kindergartens, 19.4% of school children and 3.3% of adults, which was due to great differences in the size of the immune stratum among them (IgG to HAV was detected in 8-10% of children aged 3-6 years and in 83% of adults). In 2/3 of children with HA in the foci the disease was not accompanied by jaundice, 1/5 of them having the inapparent form of this infection. In 45% of the patients HAV antigen was detected in feces, irrespective of the form of HA, 5-14 days before the appearance of hyperfermentemia, and in 2/3 of them this antigen was also detected during the first 6 days after that. Simultaneously with an increase in aminotransferase activity, all of the HA patients showed the presence of specific IgM in their blood.     

Spread of viral hepatitis in organized children's collectives and the methods for its early diagnosis]

The authors present the results of observations over 407 children aged from 2 months to 16 years from the foci of viral hepatitis in children's collective bodies. During the quarantine a determination was made in children of the glutamic-pyroracemic, glutamic-oxalic transaminases (GPT and GOT, respectively) and of the hepatitis B antigen (HBAg). A necessity of using the enzymatic tests for the purpose of early diagnosis of viral hepatitis was shown, since 84% of the cases developing in the next focus coursed as an unicteric form without any markked clinical signs; HBAg was revealed in 6.1% of the children examined. A complex examination of the personnel and of the persons who came in contact with the patients with viral hepatitis showed the ways of spread of hepatitis B in a collective body; it was found that the viral hepatitis B infection took place both by parenteral and enteral routes. The expediency of active observation over the children, recipients of blood and plasma, with determination in them of the activity of the enzymes and HBAg for early diagnosis of parenteral infection was substantiated. It was also shown that the incidence of the unicteric forms of viral hepatitis in a focus of infection depended not on the periods of gamma-globulin administration but on the age of children who contracted the infection. Thus, the prevalence of the unicteric forms of the disease over the icteric ones in children under 3 years of age was more pronounced than in older children.     

Comparative characteristics of the immunologic structure of children's collectives as regards scarlatina in different climatic zones]

An immunological study (in respect to scarlet fever) of children in children's collective bodies was conducted in 1971-1972 simultaneously in two towns-Ashkhabad and Petrozavodsk located in the contrast climatic zones. Results of Dick's test and passive hemagglutination test indicated no significant differences in the level and intensity of antitoxic immunity in children of both cities; only during the autumn period, corresponding to the seasonal increase in the incidence of scarler fever in Ashkabad, the number of immune children in this town proved to be greater than in Petrozavodsk, this being connected with a more active process of "mute" immunization. At the same time differences were revealed in the level and dynamics of antibodies to the leading types of M-antigens of hemolytic streptococci. Consequently, a higher immunological reactivity of the organism in children in Ashkhabad (promoting rapid formation of both the antitoxic and the antimicrobial immunity and limiting of the spread of marked scarlet fever affections) underlied the differences in the level of scarlet fever morbidity in different climatic zones.     

Role of carriers of the hepatitis B surface antigen as possible sources of infection in children's collectives

The complex clinico-epidemiological and laboratory surveys of the children and the staff in 71 institutions for children of preschool age were made at the period of increased viral hepatitis morbidity in these institutions, and the dynamic observations of 11 children's institutions having children with prolonged HBs-antigenemia were carried out. In the foci of viral hepatitis the level of antigenemia in the children and the staff exceeded (p less than 0.01) that in the control group. The dynamic observations (lasting up to 6 years) of the groups containing HBsAg-carriers revealed that 6 children, previously HBsAg-negative, showed a short-term HBs-antigenemia in the absence of any evidence of the parenteral (instrumental) route of infection. This fact indicates that the role of HBsAg-carriers as the possible sources contributing to the transfer of hepatitis B through everyday contacts in children's institutions cannot be ruled out. Periodic clinico-epidemiological and laboratory surveys of groups with HBsAg-carriers are recommended.     

The epidemic process of diphtheria infection in the RSFSR during the introduction of epidemiological surveillance

In this work the characterization of the epidemic process of diphtheria infection on the territory of the RSFSR under the conditions of epidemiological surveillance (1983-1986) is presented. In comparison with the period of 1979-1982, an increase in morbidity rate occurred, which accounts for more complete detection of patients with mild forms of diphtheria, including persons found to be carriers of toxigenic Corynebacterium diphtheriae. Beginning from 1983, the leveling out of seasonal morbidity rises is observed. In the total number of persons affected by this infection the prevalence of adults is noted. Among them, a decrease in the morbidity rate was registered in 1986 (the maximum decrease was observed in age and professional groups of risk), which confirms the effectiveness of measures carried out for the protection of the adult population from diphtheria. Among children, a tendency towards a decrease in morbidity rate was noted in all age groups. The existing system of epidemiological surveillance on the territory of the RSFSR is capable of stabilizing diphtheria morbidity on a sporadic level and minimizing the number of fatal outcomes. The intensification of the epidemic process in some areas of the RSFSR is due to shortcomings in the realization of different measures of epidemiological surveillance.     

Specific features of diphtheria vaccinal process in children with rheumatic diseases

Clinical and immunological examination of 55 children aged 6-15 years with rheumatic diseases, immunized against diphtheria, was carried out. All children were immunized at the stage of clinical and laboratory remission and in some cases while undergoing a prolonged course of cytostatic therapy or therapy with nonsteroid anti-inflammatory remedies. This examination demonstrated that in the overwhelming majority of children with rheumatic diseases the diphtheria vaccinal process took an asymptomatic course and had no influence on the course of the main disease. Specific features, characteristic of the immune status of this group of children, were established. In the course of the vaccinal process the restoration of the initially inhibited characteristics (the production of TNF-alpha and IL-2) to normal values were shown to occur, which was indicative of the fact that the reserve capacities of immunocompetent cells were retained in these patients. This study also revealed that immunization of children with rheumatic diseases with adsorbed DT and D toxoids with reduced antigen content was not excessive antigenic stimulation for such children, as it did not lead to immunopathological shifts, but induced transient phase changes in immunological characteristics, similar to those in healthy children. Protective levels of antibodies to diphtheria were shown to retain for a long time with considerable prolongation of intervals between booster injections. The simultaneous course of immunosuppressive maintenance therapy in the average dosage used for the corresponding age group did not inhibit the production of protective antibodies.     

The development of the epidemic process and the formation of humoral immunity to the hepatitis A virus in adolescent collectives

Additional observation on the formation of humoral immunity to hepatitis A virus has been carried out in 2,375 adolescents aged 15-17 years and belonging to 12 groups at 3 areas of the USSR. This observation has shown that in the presence of a high level of the immune stratum the spread of infection occurs, as a rule, outside the group under observation. Besides, as revealed in this study, the risk of seroconversion and the loss of specific antibodies are, respectively, directly and inversely related to the level of the immune stratum in the group. The level of the immune stratum in a given age group supposedly reflects the intensity of the development of the epidemic process at a definite area.