RESPONSE AND DECLINE OF SERUM IGG ANTIBODIES TO PERTUSSIS TOXIN, FILAMENTOUS HEMAGGLUTININ AND PERTACTIN IN CHILDREN WITH PERTUSSIS

The serum Ige antibody response and decrease to 3 Bordetella pertussis antigens was compared in children with pertussis. Sera were obtained at the first clinical visit and 1, 3 and 12 months later from 89 child ren with greater than or equal to 3 weeks of paroxysmal cough. Ige ant ibodies to pertussis toxin (PT), to filamentous hemagglutinin (FHA) an d to pertactin were determined with ELISA. Of 54 children with culture -confirmed pertussis or culture-confirmed familial exposure, 45 (83%) had a significant (greater than or equal to 3 fold) increase in PT Ige and 40 (74%) in FHA IgG antibodies, while only 29 (54%) had a signifi cant increase in pertactin IgG antibodies. Significant decreases in PT , FHA and pertactin IgG antibodies were found in 34 (63%), 9 (17%) and 28 (52%) children, respectively. In the remaining 35 who did not have culture-confirmed disease, significant PT and/or FHA IgG antibody inc reases (criteria for pertussis according to the WHO definition) were f ound in 17 (49%). Only 6 of these 17 children had a significant pertac tin IgG antibody increase. Of the remaining 18 children (who did not f ulfil WHO criteria for pertussis), significant decreases in PT and/or FHA IgG antibodies were found in 13. We conclude that a serum IgG reac tion to PT and FHA occurs in almost all children with pertussis. An in crease in pertactin IgG antibodies occurs less frequently than against PT and FHA. Significant decreases in PT or FHA IgG antibodies in chil dren with clinical pertussis might be of use as a diagnostic criterion in children brought late for examination.