Correlation of IgA, IgM and IgG antibody-detecting assays based on filamentous haemagglutinin, pertussis toxin and Bordetella pertussis sonicate in a strictly adult population.

Pertussis diagnosis among adults is primarily based on serology. In this study, receiver operation characteristics (ROC) analysis was utilized to evaluate three IgA, IgM and IgG ELISAs based on B. pertussis whole-cell sonicate (WC), pertussis toxin (PT), or combined PT-filamentous haemagglutinin (FHA) antigens in a healthy adult population and in adults suffering from symptoms consistent with pertussis. The assays were compared to a PT and FHA reference ELISA. The reference assay showed high correlation with PT- and PT-FHA-based ELISAs but low correlation was found with the WC-based ELISA. However, ROC analysis indicated that all the assays enabled fine differentiation between healthy subjects and subjects suffering from symptoms suggestive of pertussis. The WC IgA ELISA showed the best diagnostic performance [highest specificity (98.8%) with highest sensitivity (53.8%)]. We conclude that despite a low correlation between the various assays they all carry good diagnostic capability for an adult population.