Outbreak of pertussis in Basra, Iraq.

A total of 133 pertussis cases were studied during an outbreak in Basra from June to December 1996. Most were females and were immunized. Bordetella spp. was isolated in 48.1% of the cases. The isolation rate was highest among infants and decreased with increasing age, and was highest during the catarrhal stage. B. pertussis was the most common species; however, B. parapertussis infection did occur. There were some severe cases of pertussis among infants caused mainly by B. pertussis and dual Bordetella infection. Infection was transmitted by close contact with a pertussis case.