Background: Although there are several ELISA procedures to determine IgG against Bordetella pertussis, there are scarce data that allow to compare the seroprevalence detected using different kits. The objective of this study was to evaluate and to compare by three ELISA techniques the seroprevalence against B. pertussis in children.
Patients and method: 172 children 6-10 years old, vaccinated with three dose of DTPwc were studied. IgG against Bordetella pertussis was determined by two quantitative techniques (Labsystems and Serion). The qualitative detection of IgG against FHA and PT was performed by a semiquantitative method (Pertusscan).
Results: The Labsystems ELISA classified a 42.4% of the samples as positive and a 32% as borderline. The Serion method showed 52.9% of positive and 20.9% of borderline results. IgG-FHA was detected in 81.4% and IgG-PT in 75% of the samples by Pertusscan. The level of "immunity" recommended by this method was of 21.5%. The agreement between Labsystems and Serion was 45.9% (kappa index 5 0.157; p < 0.01). In the IgG-TP or IgG-FHA positive samples, the proportion of positive results obtained by Serion was superior to those obtained by Labsystems while the number of borderline results were inferior (p < 0.05).
Conclusions: Both quantitative techniques showed a high rate of not conclusive results and a very weak concordance. The large number of doubtful results obtained by Labsystems and its worse concordance with the other techniques dissuades its employment in inmunogenicity studies. The results obtained by the other two techniques present a problematic interpretation in terms of seroprevalence.