[Biological diagnosis of whooping cough: contribution of gene amplification]

An upsurge in pertussis infections, despite mandatory vaccination in France since 1966, has occurred again in developed countries due to progressive loss of vaccinal immunity and wider circulation of the causal bacterium, Bordetella pertussis. Unfortunately, the classical culture method is insufficiently sensitive and serology can only confirm diagnosis retrospectively. New techniques are needed for rapid diagnosis, and subsequent treatment and preventive measures. One new method, gene amplification using polymerase chain reaction (PCR), has been particularly useful in detecting Bordetella pertussis. PCR is highly specific and more sensitive than culture. It is thus quite useful in case of atypical clinical presentations and in previously treated or vaccinated patients. Less restrictions on sample transportation and preservation make PCR a technique which general practitioners can use for rapid easy diagnosis of pertussis.