© 2003 Canadian Medical Association or its licensors

Residents, and visitors to Canada, who were born in aforeign country with a high incidence of tuberculo-sis (TB) now account for over two-thirds of all re-ported cases of TB in this country.1,2 Because of the high incidence of TB after immigration, critics have suggested that the current chest radiography screening program, im-plemented over 50 years ago,3 be replaced with tuberculin skin test screening. What are the relative merits of these 2 approaches of screening for TB, and what are the implica-tions for practising physicians? Mycobacterium tuberculosis is a very unusual pathogen in that infection can be acquired yet remain dormant or latent for many years before reactivation. While the infection is la-tent, the person has no symptoms or detectable signs of in-fection, except for a positive tuberculin skin test reaction. In countries with a high incidence of TB, more than half of all adults have latent TB infection.4 If an infected adult move