The aim of this study is to assess the risk of tuberculosis spread in the Nord department in 1995 and to identify cases of transmission and associated risk factors by individually examining strains of Mycobacterium tuberculosis from the laboratories that isolate and identify them. The results show that there was no major epidemic situation in the Nord department in 1995. Tuberculosis was characterized by the absence of a detectable source of transmission, a low proportion of HIV-positive patients, and a high proportion of elderly, non-immigrant patients. The current epidemic therefore appears to consist mainly of cases of reactivation of old primary infections, and the risk of spread thus seems limited. (adapted from the text).