Biological diagnosis of whooping cough.

Biological diagnosis of whooping cough. Following generalized vaccination whooping cough epidemiology has been modi fied in France: a resurgence of the disease, very often clinically atypical is currently observed in non-vaccinated infants contaminated by adults. Bi ological diagnoses are selected according to this new epidemiological situa tion. These diagnoses are either direct, like culture or PCR, or indirect, such as measurement of agglutinins by agglutination or antitoxins or anti-a dhesin antibodies by Elisa or Western blot in the serum of the patients. Cu lture is a highly specific, inexpensive and reimbursed diagnosis. PCR is ex pensive, non-reimbursed and is more sensitive than culture, but cultures sh ould not be given up as they are the only technique that allow analysis of genetic and immunologic evolution of B. pertussis isolates under the effect of vaccinal strategies. Serologic methods allow a retrospective diagnosis using two sera collected at a four-week interval. Agglutination and Western blot methods are currently used for serologic diagnosis in France. Aggluti nation assay is fast, easy to perform, reimbursed and inexpensive. Western blot assay is semi-quantitative, sensitive and specific if purified antigen s are used. it is expensive but reimbursed. Elisa assay is quantitative, se nsitive and specific if purified and specific bacterial antigens are used. Elisa is expensive, non-reimbursed and is currently only used for epidemiol ogic studies or trials around the world. The type of diagnosis will be chos en according to the patient's age and immune status. (C) 2001 Editions scie ntifiques et medicales Elsevier SAS.