[Tuberculous reactions]

Intradermoreaction made with reliable tuberculin is the reference test: it is the only one that allows a therapeutic decision. The other tests can only be used as pre or post vaccinal tests, or as a technical approach for new born. In France, the reading of the IDR is difficult because BCG is almost always applied during small childhood. However it is possible to admit tuberculosis infection for vaccinated person with clear increase of the IDR positivity compared to a measured reference IDR, or when the IDR is superior to 14 mm for persons vaccinated a long time ago. For immunocompetent persons, a tuberculosis infection admitted on an isolated IDR (not associated with tuberculosis disease) does not need chimiprophylaxy for children under five, or in case of clear and recent increase of IDR, or in a context of contamination. For a HIV positive person, a tuberculosis infection admitted on an isolated IDR implies a systematic chimioprophylaxy, but the IDR looses its signification as the immunodepression progresses. An attempt to study the prevalence of tuberculosis infection at twenty in France for vaccinated persons has been realized. In 1984 the admitted rate is over 8%, superior to the calculated rate from Styblo and Sutherland tables. That seems to mean that tuberculosis infection is under evaluated in France.