[Prevention of tuberculosis].

The aim of primary prophylaxy against tuberculosis is to prevent new cases of infection. The diagnosis, early treatment and initial identification of patients with tuberculosis can decrease the risk of dissemination. Measures should be particularly severe in cases of multiresistant tuberculosis. Exposed subjects should be protected by BCG vaccination which reduces the risk of contamination by half. In particularly susceptible exposed subjects (children, immunodepressed subjects) separation is need and in certain cases chemoprophylaxy should be prescribed (small non-vaccinated children, HIV seropositive subjects). Isoniazid is classically recommended for 3 months. In case of multiresistant tuberculosis, other chemoprophylaxy protocols are proposed (ethambutol, pyrazinamide and ofloxacine). The aim of secondary chemoprevention of tuberculosis is to avoid tuberculosis infection from developing into full blown disease. Chemoprophylaxy is the only effective treatment. It is proposed after recent asymptomatic reactivation (newly positive tuberculin test) in children and immunodepressed patients. Chemoprophylaxis is based on isoniazid for 6 months. Other protocols are being evaluated in HIV positive patients. This secondary chemoprophylaxy is also proposed to subjects with tuberculosis sequellae and who are susceptible of becoming immunodepressed due to HIV infection or onset of an organ graft protocol. The presence of a resistant strain can modify management.