Pertussis resurgence among vaccinated children in Khairpur, Sindh, Pakistan.

OBJECTIVES: To investigate the aetiology of persistent cough among vaccinated children as suspected cases of pertussis in Khairpur District, Sindh, Pakistan. Pertussis or whooping cough, caused by Bordetella pertussis, is re-appearing in many countries despite vaccination coverage. In Khairpur, persistent cough and symptoms similar to pertussis among vaccinated children are common but the aetiology has not been investigated previously.

STUDY DESIGN: B. pertussis was isolated from cough samples of suspected pertussis patients (n = 700) using the cough plate method with charcoal agar.

METHODS: Isolation and confirmation of the clinical isolates of B. pertussis was performed by culture on Bordet-Gengou medium, biochemical tests and polymerase chain reaction.

RESULTS: In total, 22 strains of B. pertussis were isolated from clinical cough samples.

CONCLUSION: To the authors' knowledge, this is the first report of the presence of pertussis in vaccinated children in Khairpur. There is a need for continuous monitoring of pertussis after immunization programmes in order to assess the efficacy of pertussis vaccination.