BCG and New Tuberculosis Vaccines

Abstract

Tuberculosis (TB) remains a global epidemic. TB is primarily a pulmonary infectious disease and it is caused by exposure to airborne M. tuberculosis bacilli. Approximately one third of the world population has been infected by M. Tuberculosis and 10% of these people may develop active TB at some point of their lives when their host defense is weakened. Thus, each year eight million people develop TB worldwide and two million of people die from the disease (Kaufmann 2001). The risk of developing active TB in HIV-infected patients is 30-fold greater than HIV-negative patients. More than 10 million people are co-infected with both M. tuberculosis and HIV worldwide and at least a half million of these people die from TB each year, thus bringing the annual TB-related death toll to 2.5 million. The increasing emergence of multi-drug-resistant (MDR) strains of M. Tuberculosis further compounds the TB epidemic, as a result of poor compliance with anti-TB therapeutic regimens (50 million people have been infected with MDR-TB). Normally, a combination of several anti-TB antibiotics needs to be taken daily for a minimum of 6–12 months. A similar regimen is also recommended for preventive chemotherapy in TB-infected HIV patients who have not yet developed active TB. It is noteworthy that the difficulty in completing such lengthy regimens is encountered widely, not only in the developing countries, but also in disadvantaged groups in the developed countries (Kaufmann 2001; Ginsberg 2000).