Study objectives: The incidence and prevalence of
pertussis in adults have increased in recent years. It has been shown
that previously immunized adults and adolescents are the main sources
of transmission of Bordetella pertussis. The aim of this
study was to describe the clinical presentation and the clinical course
of pertussis in children and young adults who were immunized previously
against B pertussis.
Subjects: Children and young
adults who were reported by local physicians to the Department of
Epidemiology in the Israeli Ministry of Health with serologically
confirmed pertussis and who were immunized previously were included.
Information sought included personal data, epidemiologic data, signs
and symptoms, laboratory results, initial diagnosis, and
Results: In the 95 previously immunized
patients with serologically confirmed pertussis (mean age[±
SD], 8.9 ± 4.4 years old; range, 5 to 30 years old),
the mean duration from onset of symptoms until the final diagnosis of
pertussis was 23 ± 15 days. The disease was usually atypical and
generally mild. All the described patients had cough, usually
prolonged, lasting 4 ± 3.6 weeks. Only 6% had the classic whoop.
The mean WBC count was 8.7 ± 2.6 cells/mm6, and the
lymphocyte count was 40 ± 12%. Two patients were admitted to the
hospital for severe pneumonia. Among the reported cases, the proportion
of patients between the ages of 10 and 45 years increased from 6.5%
during the period from 1971 to 1980, to 26% during the period from
1980 to 1990, and to 38% during a 1989 outbreak.
Conclusions: Pertussis in previously immunized individuals
is usually characterized by an atypical and relatively mild clinical
course. Patients suffer mainly from a prolonged and persistent cough.
Early diagnosis may lead to prompt administration of therapy.
Prophylaxis of exposed persons might be effective in decreasing both
severity and transmission of the disease.