A complex of measures carried out with a view of effecting the epidemiological surveillance of diphtheria infection has made it possible to study the level and intensity of immunity to diphtheria and tetanus, determined in the passive hemagglutination test, in the child and adult population and to reveal groups, least protected against diphtheria infection. Bacteriological studies on the biological properties of Corynebacterium diphtheriae have revealed the contamination of various groups of children with this infective agents and permitted its complete characterization with the determination of its sero-, phago- and corycinovariants.
Adolescent Adult