[Seroprevalence of antibodies against lipopolysaccharides of Bordetella parapertussis in patients with prolonged caught in Poland].

Introduction: Bordetella parapertussis is a bacterium closely related to Bordetella pertussis, also causes a pertussis - like symptoms in humans. Because of unsatisfactory level of routine microbiological diagnosis of B. parapertussis infections in Poland most of parapertussis cases are not reported. The aim of the presented study was to investigate incidence of B. parapertussis in patients with cough in Poland using serology method.

Methods: Serum IgA, IgG and IgM antibodies were determined in 1192 serum samples obtained from patients with respiratory infections and chronic cough and who were previously suspected of B. pertussis infection. As a control we used 258 sera from healthy people - blood donors. The LPS antigen was extracted by Westphal method from wild B. parapertussis strain isolated in Poland. For exclusion of possible false positive results with B. pertussis some of the sera were tested against the purified pertussis toxin (PT).

Results: The diagnostically significant level of IgA antibodies to LPS of B. parapertussis was detected in 11.9%, IgG in 12.2% and IgM in 9.6% serum samples. More often the antibodies were diagnosed in women than in men. In 63 serum samples, previously positive in NovaTec ELISA with mixed antigen of pertussis toxin and filamentous hemagglutinin we found also IgA and IgG antibodies to LPS of B. parapertussis. However, after use of purified pertussis toxin antigen in ELISA we confirmed the B. pertussis infections only in 28 cases.

Conclusions: This study shows that B. parapertussis is a serious causative agent of infections in patients with prolonged caught in Poland. The serodiagnosis ofparapertussis should be conducted with sera obtained from patients suspected in clinical investigation for pertussis but negative in serological investigation with purified pertussis toxin antigen.