ORIGINAL STUDY Prospective Multinational Study of Pertussis Infection in Hospitalized Infants and Their Household Contacts

Background: Increased incidence of pertussis has been noted among infants too young to be immunized. We studied the disease burden of pertussis in pediatric intensive care units and the source of infection in several Asian, European and Latin American countries. Methods: The study was conducted in 7 countries from September 2001 to January 2004. Children 1 year of age were enrolled from pediatric intensive care units (PICU) and pediatric wards if they presented with respiratory failure, apnea, bradycardia, or cough accompanied by paroxysms, vomiting, whoop or cyanosis. House-hold members of pertussis-positive index cases were asked to answer a questionnaire and provide diagnostic specimens