TUBERCULOSIS - CONTACT TRACING AND PREVEN TIVE CHEMOTHERAPY

Tuberculosis is transmitted from patients with lung disease to sensiti ve individuals by inhalation of infectious particles expelled during c ough. Therefore, the search for infected subjects among relatives of p atients with infectious tuberculosis is the best method of preventing later development of the disease in populations where the prevalence o f tuberculosis is low. Contact tracing relies on the tuberculin skin t est, followed by chest X-ray if indicated and bacteriological examinat ion of sputum. In recently infected subjects, particularly the young, preventive chemotherapy has been shown to decrease the risk of later d isease.