Pertussis in adults with persistent cough: a prospective follow up study in primary care

Despite high coverage of pertussis vaccine, B. pertussis has remained endemic and adults are recognized as reservoir for infection among incompletely immunized infants. Between November 15th 2004 and November 14th 2006, 37 general practitioners, attending 56,658 adults, recruited all patients with persistent cough. A diagnosis of pertussis was considered in those with an unexplained cough, lasting 14 or more days and a positive polymerase chain reaction (PCR) or enzyme-linked immunosorbent assay (ELISA) IgG anti-Pertussis Toxin (PT). During the period of the study 86 patients presented with persistent cough (106 cases per 100,000 person-years). According to laboratory criteria, 35% were classified as associated to B. pertussis, with an incidence of 34 cases per 100,000 person-years (95% CI 23 to 46 per 100,000 person-years).