Diagnosis of Pertussis

During a local outbreak of pertussis mainly involving school-children and adults, 71 patients with suspected whooping cough and 25 of their household contacts were studied in the course of 1 day so as to compare enzyme-linked immunosorbent assay (ELISA) with bacterial isolation in the diagnosis of pertussis. Serum samples and two nasopharyngeal swabs were collected from all persons. Five different culture media were used. Twenty-eight cases were diagnosed within 2 days by measuring IgM- and IgA-class antibodies to Bordetella pertussis in the first serum samples of patients. Fifty cases were identified when paired serum samples were used. Cultures were positive in only nine patients. The results show that ELISA is a valuable aid in the diagnosis of pertussis in patients with negative cultures.