[Clinical study on 45 cases of adult and adolescent pertussis].

We studied 45 cases of adult and adolescent pertussis. The diagnosis of pertussis was made by two criteria. 1) 4-fold increase in antibody against B. pertussis with paired sera (A group: 15 cases). 2) Titer of anti PT antibody above 100 EU/ml (B group: 30 cases). Paroxysmal cough was 100% in A and B group, whooping cough was present 93% in A group, 92% in B group, posttussive vomiting was 78% in A group, 67% in B group. Familial infection was 18 cases of 15 families (33%). Marked lymphocytosis was not detected in any stage of pertussis. When initial examination was made 3-4 weeks after cough onset, the proof of 4-fold increase in antibody against B. pertussis with paired sera was low. Nine cases (20%) of 45 adult and adolescent pertussis cases had bronchial asthma, but bronchial asthma did not prolong the duration of cough. As proof of 4-fold increase in antibody against B. pertussis with paired sera in adult and adolescent pertussis is difficult, it is expected that the cut-off point of antibody titer against B. pertussis in single sera is determinated rapidly.