Grant: Operating Grant

Tuberculosis (TB) infects 2 billion people, and 9 million people develop active disease every year. Because these individuals eventually present to health-care providers, health care workers are especially vulnerable to TB exposure and infection. For this reason, health workers are screened with tuberculin skin testing to identify and treat TB infection. However, the tuberculin test, the oldest diagnostic test in medicine, has several limitations in accuracy and reliability. Recently, new blood-based tests for TB infection have been developed, called interferon-gamma (IFN-g) release assays. These blood tests seem to be more accurate than the tuberculin test, and they have several features that make them attractive for screening health care workers. We have enrolled a large number of health workers in Canada and India, and have screened them with both the skin test and the blood test. We propose to follow them up to determine the risk of new infections and determine the utility of interferon-gamma assays. Worldwide, thousands of health workers are screened for TB. The current screening approach is complex, costly, and relies on a century-old imperfect skin test. It is, therefore, important to know if newly available blood tests should replace the tuberculin test. Our project will address key questions that will determine whether to continue to use the tuberculin test, or substitute the skin test with interferon-g assays.