Serologic diagnosis of whooping cough by enzyme-linked immunosorbent assay.

Pernasal swabs were obtained on 3 consecutive days from 146 children referred for hospital admission with suspected whooping cough, and immunoglobulin A and immunoglobulin M antibodies to Bordetella pertussis were measured by enzyme-linked immunosorbent assay. The clinical features in 113 of the children were considered consistent with the diagnosis. Sixty-four cases were confirmed by serology, which showed a greater sensitivity (57% vs. 35%) than pernasal swab culture with no loss of specificity (100%). Paired serum samples were necessary for diagnosis in 30 (47%) of these 64 cases. Seventeen (43%) of 40 cases confirmed by pernasal swab culture had negative serologic results. Most of these were young infants who showed a less reliable antibody response. Detection of antibodies to B. pertussis by enzyme-linked immunosorbent assay can be a valuable additional test in the differential diagnosis of whooping cough but is not appropriate as the sole diagnostic test.