SEROLOGICAL DIAGNOSIS OF PERTUSSIS

Serological methods are indirect methods allowing a retrospective diag nosis using two serums at four week interval. Many serological tests w ere used since the discovery of Bordetella pertussis, but most of them lack reproducibility, sensitivity and specificity. The last years, st udies on B. pertussis allowed to characterize and to purify factors in volved in the virulence of the bacteria. Two technics can now be used : immune enzymatic assay (ELISA) which is quantitative, sensitive and specific if antigen used is highly purified; Western blot which is sem i-quantitative sensitive and specific if purified antigen is used. The advantage of this technic is that a smaller amount of antigen is nece ssary. Those test used antigens which are not commercialized and they are only used for epidemiological and clinical assays. Their cost is h igh. Technics actually commercialized are agglutination detecting anti -agglutinogen antibodies. This technic is easy to perform, but not sen sitive on infected patients; it is useful for the detection of vaccina l antibodies; immune enzymatic test (ELISA) using B. pertussis suspens ion is cheap, easy to perform but not very specific.