ABSTRACT
Pertussis is a pediatric infectious disease with one of the highest degrees of infectivity. Although pertussis may cause asymptomatic infections in children and adults with immunity, it can cause life-threatening diseases in newborn babies or infants. We report three cases of pertussis in infants <3 months of age without DTaP immunization who have received symptomatic treatment with the diagnosis of bronchiolitis from other hospitals, and subsequently correctly diagnosed and treated. The patients did not have the characteristic whooping cough, but the main symptoms were episodic cough, intermittent vomiting, and cyanosis. Based on culture results for Bordetella pertussis and PCR, pertussis was diagnosed and treated without any complications. As it is assumed that adults, adolescents, and asymptomatic patients may serve as sources of infection, immunization with Tdap vaccine is recommended to prevent dissemination of pertussis from adolescents and adults to infants, and thus maintain herd immunity.