Tuberculosis: the return of an old enemy.

Tuberculosis is an ancient human scourge that continues to be an important public health problem worldwide. The increasing number of multidrug-resistant (MDR) M. tuberculosis isolates from both AIDS and non-AIDS patients is an ominous trend that threatens tuberculosis eradication programs both in the U.S. and overseas. New antituberculosis vaccines with therapeutic properties are urgently needed for human immunodeficiency virus-infected individuals, as well as health care professionals likely to be exposed to MDR tubercle bacilli. Recombinant DNA vaccines bearing protective genes from virulent M. tuberculosis are being developed using shuttle phasmids to transfer genetic material from one mycobacterial species to another. Improved assay procedures are needed to measure the protection afforded by these new vaccines under experimental and field test conditions. Tuberculosis vaccine development should be given a high priority in current medical research goals.