ANTIBODIES TO FILAMENTOUS HEMAGGLUTININ OF BORDETELLA-PERTUSSIS AND PROTECTION AGAINST WHOOPING-COUGH IN SCHOOLCHILDREN

A pertussis outbreak was studied prospectively in an elementary school with 39 pupils. All had been immunized with at least three doses of F innish diphtheria-tetanus toxoid-pertussis vaccine. Diagnosis of pertu ssis was based on culture, polymerase chain reaction results, and EIA serology using filamentous hemagglutinin (FHA), pertussis toxin, and 6 9-kDa outer membrane protein as antigens. At the first sampling, 21 ch ildren had symptoms suggestive of pertussis, and 18 were healthy. Of t he latter, 8 remained healthy without any antibiotic treatment and 9 d eveloped clinical pertussis 1-22 days later. One child developed cough later, but this symptom did not meet criteria for pertussis. The mean levels of IgG, IgM, and IgA antibodies to FHA were significantly high er in 8 healthy children than in 9 children who developed pertussis af ter the first sampling (P < .001, P = .027, and P = .011, respectively ). The results show that antibodies to FHA of Bordetella pertussis in immunized schoolchildren correlate with protection against pertussis.