[Intradermal tuberculin test].

Mantoux test expresses a delayed hypersensitivity induced after either BCG vaccination or a BK contact. In France, a purified protein fraction is used. The quality of technique and lecture are essential. The lowest positivity limit is > 5 mm. Sensitivity and specificity are imperfect. For the interpretation of positivity, the most important factors are the age of vaccination (the younger the child is, the lower the reaction is) and the infection prevalence rate in the group considered (the lowest it is, the highest a criteria may be used for induration > 15 mm). The background is most important for interpretation. The main situations are a postvaccinal test, a diagnosis of infection (or illness) or the environment of a contagious adult. A lot of situations are less clear and require the knowing of a risk factor (risk people, contagion...). In spite of these limits, Mantoux test is the only valid technique, useful when considered with other points: collective (prevalence of the illness in some groups) or individual (contagion, clinical or radiological signs...).