Pertussis in adults. A study in an Italian population with chronic cough

Pertussis is commonly regarded as a disease of children but a number of clinical studies show that quite often it occurs in older children and adults, too. The purpose of the present study was to determine the prevalence of Bordetella pertussis infection in an Italian population of adults with persistent non-productive cough.

Pertussis was considered in the differential diagnosis of a prospective case series of 180 adult patients with unexplained non-productive chronic cough. To diagnose pertussis, nasopharyngeal swabs for culture were obtained and antibodies IgA and IgG against multiple B. pertussis whole body antigens were counted by enzyme-linked immunosorbent assay in a single serum sample.

The prevalence of pertussis with unexplained persistent cough was 10% of the cases. Significantly high amounts of specific IgA, that is at least 2 standard deviations greater than the geometric mean of the control group, were observed in 19 subjects. None of these patients had the typical symptoms of pertussis.

Pertussis is quite a common cause of persistent cough in adults and should always be considered in differential diagnosis. Pertussis cases can easily be diagnosed by demonstrating IgA antibodies high titers in single serum samples, compared with those of population controls.