Frequency of pertussis is highly variable from country to country and it depends on multiple factors including case definitions and type of surveillance systems used. Many countries recently reported an increase of pertussis cases especially in infants and adolescents.
From April 2006 to March 2011, 15-year-old patients hospitalized with suspected or proven pertussis were reported to the Swiss Pediatric Surveillance Unit. Patients with ≥14 days of cough plus paroxysms, whooping or post-tussive vomiting fulfilled the clinical case definition of pertussis. For laboratory confirmation, Bordetella pertussis polymerase chain reaction was offered free of charge.
Data were available from 159 of 173 reported cases and 130 (90% of them <12 months old) were eligible including 125 laboratory-confirmed B. pertussis infections. Rates per 100,000 population were 2.6 (<16 years) and 38.8 (<12 months), respectively. Most frequent complications were cyanosis (63%) and sleep disturbance (60%); 35 (27%) patients received intensive care and 1 patient died. Source of infection was known in 79 (61%) patients and was mainly a sibling, parent or both. Most patients were unimmunized (65%) or incompletely immunized (30%).
The high rate of pertussis hospitalization in young infants established in this surveillance project and the incomplete pertussis immunization status in almost all hospitalized patients require further efforts for improvement. In addition, introduction of pertussis immunizations for all adolescents (in 2013), young adults (in 2012) and pregnant women (in 2013) in Switzerland should increase indirect protection of vulnerable newborns and infants too young to be fully immunized.