The exact nature of the interaction between leprosy and tuberculosis has been debated for over a century. They share common antigens as evidenced by conversion of lepromin intradermal tests after the administration of Bacille-Calmette-Guerin (BCG) and the partial protection offered by BCG against leprosy. Though an increased frequency of pulmonary tuberculosis in patients with lepromatous leprosy may occur as a result of malnutrition, tuberculosis occurs across the spectrum of leprosy. An inherent impaired immunity against both mycobacterial organisms has been postulated as the etiology for dual infection; however, it appears that the anergy in leprosy is pathogen-specific . Some investigators have speculated that leprosy and tuberculosis are antagonistic diseases on the basis of immunologic, clinical, and epidemiologic data. The historical high rates of tuberculosis have also been postulated as one reason for the decline of leprosy in Europe. Since tuberculosis is a more aggressive illness than leprosy, the researchers suggest that patients with tuberculosis and leprosy were more likely to have died faster, reducing the reservoir for M. leprae. The relationship between the two mycobacterial diseases continues to be enigmatic despite decades of research.
Last date updated on June, 2014