ELISA for the routine determination of antitoxic immunity to tetanus

Serum samples from 727 persons with different vaccination histories were assessed for tetanus antitoxin content in an enzyme linked immunosorbent assay (ELISA) and tested for tetanus toxin neutralization activity in mice in order to compare the results obtained by the two methods. Neutralizing antibody activities in sera from individuals previously completely vaccinated correlated well with results obtained by ELISA and the accuracy increased with increasing antitoxin concentration in serum. This correlation was observed in sera from persons vaccinated recently as well as in sera from persons vaccinated many years ago. In sera from persons with an incomplete vaccination history ELISA was found to be an unreliable tool for the prediction of in vivo results. Many of these sera had antitoxin levels by ELISA far above the in vivo values, probably due to the presence of non specific or low avidity antitoxin which is detected in ELISA. The lowest ELISA value reliably predictive of protective antibody activity in serum irrespective of vaccination history was found to be 0.16 IU/ml. It was concluded that ELISA is useful for larger population studies as an initial test, but sera with an antitoxin content below 0.16 IU/ml should also be assessed in a neutralization system.     

Approaches to determining the extent of tetanus immunity using an immunoenzyme method

The immunological survey of 3435 cattle-breeders of the Rostov region was carried out with the use of the enzyme immunoassay (EIA). The survey made it possible not only to establish the intensity of collective anti-tetanus immunity, but also to evaluate the quality of immunization. Among subjects with the known history of immunization the protective antitoxic titer was detected in 96.8 +/- 1.2% of cases and among subjects whose immunization history was unknown, in 75.3 +/- 0.8% of cases.     

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.     

Microparasite population dynamics and continuous immunity.

A mathematical model is presented for the transmission of a microparasite where the hosts occupy one of two states, uninfected or infected. In each state, the hosts are distributed over a continuous range of immunity. The immune levels vary within hosts due to the processes of waning of immunity (when uninfected), and increasing immunity (when infected), eventually resulting in recovery. Immunity level also influences the host''s ability to infect or be infected. Thus the proposed model incorporates both inter- and intra-host dynamics. It is shown from equilibrium results that this model is a general form of the susceptible-infected-resistant (SIR) and susceptible-infected-susceptible (SIS) family of models, a development that is useful for exploring multistrain pathogen transmission and use of vaccines which confer temporary protection.     

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.