Seroprevalence of Immunoglobulin M/A/G antibodies against Bordetella pertussis and Bordetella parapertussis among asymptomatic children at 6-8 of age in Turkey

Bordetella pertussis infection is a vaccine preventable disease, but immunity following the vaccination is not life-long. Moreover parapertussis may share similar clinical presentation with pertussis and mostly recognized in prolonged bronchitis. Although the serology of pertussis has been well studied, those of parapertussis have not. We herein investigated antipertussis and antiparapertussis serology in asymptomatic healthy children. We examined IgM, IgA and IgG antibodies against B. pertussis and B. parapertussis among 100 asymptomatic children aged from 6 to 8 years who got regular vaccination. The antibody titers were measured by indirect immunofluorescence test (IFA). 10% of them had IgA titers of > or = 100 EU/ml, 33% had IgM titers of > or = 320 EU/ml who could be considered as acute or recent pertussis infection and 89% had IgG titers > or = 100 EU/ml as a protective level of pertussis. Bordetella parapertussis antibody levels of IgG, IgA and IgM were detected in 33%, 17%, and 11% respectively. We suggest 2 explanations for the acquisition of pertussis and parapertussis antibodies in our children: (1) asymptomatic pertussis and parapertussis infections are common; (2) Although higher values of IgG observed, acute infection markers still persisted, and one problem in this regard may be waning immunity against pertussis. Of the strategies considered, the addition of a preschool booster is therefore a priority in Turkey.