Results of conducting an epidemiological survey of diphtheria in 21 territories of the RSFSR

As the result of epidemiological survey of diphtherial infection, carried out in conformity with the unified methodological recommendations in 21 regions of the RSFSR during 1980-1981, the expediency of such experiment was established. Immunity to diphtheria in children aged up to 14 years was high: children with negative Schick tests constituted 96.9-99.1%. No biological changes in Corynebacterium diphtheriae occurred during the term of observation. Toxigenic C. diphtheriae showed a high level of pathogenicity. The epidemiological survey contributed to a more thorough detection of diphtheria patients and carriers releasing toxigenic C. diphtheriae. The quality of clinical bacteriological diagnosis improved. In rare cases angina with the concomitant carriership of toxigenic C. diphtheriae could be diagnosed with the indispensable serological examination of the patients by Jensen's method.     

Epidemiology of diphtheria in the RSFSR during mass immunization over many years

The work defines the characteristic epidemiological features of diphtheria in the RSFSR at the present moment when a high level of antitoxic immunity is generally determined in children. With the diphtheria morbidity level having, on the whole, a sporadic character in the RSFSR, the intensification of the epidemic process has been found to occur in some regions. Changes in the ratio of morbidity rates among the urban and rural population are observed, the morbidity rate among the latter have the tendency towards increase. At present the characteristic feature of diphtheria is the prevalence of adults in the general morbidity structure. An important fact is a permanently high level of toxigenicity in Corynebacterium diphtheriae. As before, autumn is the season of the highest morbidity level.     

Humoral immunity to diphtheria and tetanus in pregnant women and newborn infants

Pregnant and parturient women have been examined in different regions of the USSR: Moscow, the Turkmen SSR, the Azerbaijan SSR and the Uzbek SSR. Altogether 720 placental sera and 522 funic sera have been checked for the presence of antibodies to diphtheria and tetanus toxoids in the passive hemagglutination test. Considerable groups of women with the insufficient level of immunity to diphtheria (40-66%) and tetanus (42.1-58.8%) have been revealed in different republics. Among women over 70 years the percentage of persons with the absence of antibodies or having low antibody titers has proved to be even higher. The comparative analysis of antibody titers has shown a correlation between antibody titers in mothers and newborn infants in 83.6% of cases for diphtheria toxoid and in 72.9% of cases for tetanus toxoid. These data show that among parturient women and newborn infants large groups remain unprotected against diphtheria and tetanus, which indicates the necessity of correcting the immune status of women of the productive age.     

Determination of antibodies to diphtheria and tetanus toxoid by latex agglutination technique

A micromethod of latex agglutination was worked out for determination of antibodies to diphtheria and tetanus toxoids. It is suitable for pediatrics since a minimum amount of serum (0.05 ml.) is required, which can be used without being inactivated or absorbed. Particles of polystyrene latex of Czechoslovak production were used as antigen carriers thus enabling better standardization of the technique. The particles are well defined both in physical and chemical terms and replace red blood cells in passive hemagglutination. The method was compared with passive hemagglutination in a dynamic study of children inoculated at monthly intervals with the trivalent vaccine Alditepera.     

Immunity to tetanus of a rural population in a Greek county

Tetanus is still a common problem in countries with poor health conditions. On the contrary, where there is a systematic program of vaccination in children it is very rare. The aim of this study was to check the immunity level of a representative sample of rural people from villages of Achaia County in Southern Greece. Samples were taken from 140 locals during a six-month period (January till July 2002). In each sample, we estimated IgG antibodies against Clostridium tetani toxin. A protection level of 0.1 IU/ml was set. 15.7% of the people had sufficient immunization cover while a statistically significant superiority of immunized men was found. The results of this study revealed low immunity percentage of the examined inhabitants and a vaccination program against the disease has been proposed to the local health authorities.     

Comparison of immune responses to diphtheria and tetanus toxoids of various mouse strains

Immune responses of 11 mouse strains with known genetical characteristics and two outbred strains to diphtheria and to tetanus toxoids were compared. Both diphtheria and tetanus antitoxins were titrated by passive hemagglutination. From the pattern of the immune response, the mouse strains tested may be classified into four groups. [1] Strains ddY (SPF) and ddY (conv) and those with haplotype H-2b, such as C57BL/6 and C57BL/10, were high responders to both toxoids. [2] Strains with H-2d, such as BALB/c, B10.D2 and DBA/2Cr, were intermediate responders to both toxoids. [3] Strains with H-2k, H-2a or, H-2m, such as C3H/He, B10.BR, B10.BR/SgSn, B10.A/SgSnJ and B10.AKM/O1a, were high responders to diphtheria toxoid but low responders to tetanus toxoid. [4] The strain with H-2h4, B10.A (4R), was a poor responder to both toxoids.     

Quantitative estimation of diphtheria and tetanus toxoids. 4. Toxoids as international reference materials defining Lf-units for diphtheria and tetanus toxoids

The Lf-unit, which is used in the control of diphtheria and tetanus toxoid production and in some countries also to follow immunization of horses for production of antitoxins, has hitherto been defined by means of antitoxin preparations. A diphtheria toxoid and a tetanus toxoid preparation, both freeze-dried, were examined in an international collaborative study for their suitability to serve as reference reagents in the flocculation tests and for defining the Lf-units. It was shown that flocculation tests using the reference toxoids are very reproducible and reliable and the WHO Expert Committee on Biological Standardization established: the toxoid called DIFT as the International Reference Reagent of Diphtheria Toxoid for Flocculation Test with a defined content of 900 Lf-units of diphtheria toxoid per ampoule; and the toxoid called TEFT as the International Reference Reagent of Tetanus Toxoid for Flocculation Test with a defined content of 1000 Lf-units of diphtheria toxoid per ampoule.     

Booster vaccination against tetanus and diphtheria: insufficient protection against diphtheria in young and elderly adults

We have recently demonstrated that single shot vaccinations against tetanus and diphtheria do not lead to long-lasting immunity against diphtheria in elderly persons despite administration at 5 year intervals. In the present study we have immunized a group of young adults against tetanus and diphtheria to compare the pre- and 28 days post-vaccination immune responses in the young group with results of the same vaccination performed in an elderly group of a previous study. We also studied protection in both groups 5 years after vaccination. We compared antibody titers at all three time points and also analyzed the T cell responses in both age groups 5 years after vaccination.Before vaccination 9 % of the elderly persons were not protected against tetanus, and 48 % did not have protection against diphtheria. In the young group all participants were protected against tetanus, but 52 % were also unprotected against diphtheria before vaccination. 28 days after vaccination 100 % of all participants had protective antibody concentrations against tetanus and only a small percentage in each age group (<10 %) was unprotected against diphtheria. 5 years later, 100 % of both cohorts were still protected against tetanus, but 24 % of the young and 54 % of the elderly group were unprotected against diphtheria. Antibody concentrations against diphtheria measured by ELISA correlated well with their neutralizing capacity. T cell responses to tetanus and diphtheria did not differ between young and old persons. We conclude that booster vaccinations against tetanus and diphtheria according to present recommendations provide long-lasting protection only against tetanus, but not against diphtheria, independently of age. In elderly persons, the level of protection is even lower, probably due to intrinsic age-related changes within the immune system and/or insufficient vaccination earlier in life.     

Vitamin A as adjuvant to the mouse immune response to pertussis, tetanus and diphtheria vaccines

Vitamin A was used as adjuvant, comparatively with Al(OH)₃, in pertussis, tetanus and diphtheria vaccines. Both groups induced a primary immune response in mice, and one single booster dose elevated the antibodies titers in average 554 times to vitamin A groups and 104 times to Al(OH)₃. These antibodies titers correlate with sera IL-4 in immunized animals, suggesting a Th2 response. Other cytokines detected in the sera and/or lymphocytes culture supernatants (IL-2 and IFN-) indicated that vitamin A could also modulate a Th1 response in DPT and acellular pertussis vaccines.     

The level of postvaccinal immunity to diphtheria, tetanus and poliomyelitis in relation to the number of inoculations]

The work was aimed at the comparative study of the intensity of immunity to diphtheria, tetanus and poliomyelitis, depending on the number of injections of adsorbed diphtheria-pertussis-tetanus (DPT) vaccine and poliomyelitis vaccine, for the purpose of finding out the possibility of reducing the antigenic load given to children without diminishing the intensity of immunity. To determine the level of immunity to diphtheria and tetanus, 1900 children under school age were serologically studied by the micromethod in the passive hemagglutination test. The intensity of immunity to poliomyelitis virus was studied in 333 children by means of the neutralization test. The immunogenic properties of the diphtheria component of adsorbed DPT vaccine were found to be less pronounced than those of the tetanus component of the vaccine, which made it impossible to reduce the antigenic load by decreasing the number of vaccinations against diphtheria. The results of the study of postvaccinal immunity to poliomyelitis suggest that during the first and second year of life the course of vaccination against poliomyelitis may be reduced to 3 injections.