Intradermal tuberculin test (Mantoux 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 > 5mm. Sensitivity and specificity are unperfect. For the interpr etation of positivity, the most important factors are the age of vaccinatio n (the younger the child is, the lower the reaction is) and the infection p revalence rate in the group considered (the lowest if is, the highest a cri teria may be used for induration > 15mm). The background is most important for interpretation. The main situations are a postvaccinal test, a diagnosi s 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 (ris k people, contage...). In spite of these limits, Mantoux test is the only v alid technique, useful when considered with other points: collective (preva lence of the illnesss in some groups) or individual (contage, clinical or r adiological signs...). (C) 2000 Editions scientifiques et medicales Elsevie r SAS.