Serological immunity to diphtheria and tetanus in healthy adults in Delhi, India

Widespread childhood immunization with DPT (diphtheria, pertussis and tetanus) has largely eradicated diphtheria and tetanus from many countries. The reduction in the circulation of toxigenic strains has resulted in less natural boosting of adult immunity. As a result, the adult population in countries with high childhood immunization coverage have become susceptible to the disease. The duration of immunity after primary immunization to diphtheria and tetanus is limited and a reduction in immunity is common in adults. With this perspective, the present study was carried out on a random serum sample of 255 healthy individuals aged 20-50 years. The serum samples were tested for immunoglobulin G levels against diphtheria and tetanus by enzyme immuno assays. Fifty-three per cent of adults were unprotected; 22% were seen to have only a basic protection against diphtheria; 25% were protected against both diseases; and 47% were susceptible to tetanus. The susceptibility was seen to increase with age. To avoid epidemics in the future, immunity must be improved. It is important to treat even the most trivial wound with care and tetanus toxoid immunization. Also, it is necessary to monitor the community for immunity to diphtheria using standard techniques in order to undertake epidemiological surveillances of, and prevention from, these dreadful diseases.