[Humoral immunity against pertussis and its prevalence in population].

Levels of IgG and IgA to complex of Bordetella pertussis antigens were assessed in 503 healthy children aged 1 - 14 years, 75 adolescents aged 15 - 17 years, and in 504 adults aged 18 - 54 years. The highest level of IgG was observed in children aged < 5 years. In older age groups progressive decrease of IgG level was noted, which more most prominent in 9 - 11 year-olds with subsequent stabilization of the level in adolescents and adults. Significant heterogeneity of IgG level was noted in all age groups. Rate of detection of increased IgA level correlated with age-related decrease of IgG level and increased from 2 - 5% in children aged 1 - 5 years to 12 - 16% in older children and adults. Obtained data point to low levels of immunity against pertussis in older children, adolescents and adults and high undetected incidence of pertussis in studied population.