%A Truman RW %A Gillis TP %T The effect of ultraviolet light radiation on Mycobacterium leprae %0 Journal Article %D 2000 %J International Journal of Leprosy and other Mycobacterial Diseases %P 0148-916X %V 68 %N 1 %X Ultraviolet (UV) light is recognized as a potent sterilizing aid, but its relative effectiveness against Mycobacterium leprae has not been shown. We examined the influence of UV on the growth and metabolic activity of M. leprae harvested fresh f rom foot pads of nude mice. Temporary static suspensions were exposed to timed intervals of UV radiation generated f rom a fixed source to constitute dosages ranging f rom 0-12.64 x 104 erg/cm2. The metabolic activity of the bacilli was indexed by the oxidation of 1 14C-palmitate in BACTEC 12-B vials. The long-term effects of irradiation on cell division and growth were assessed by inoculation of BALB/c mouse foot pads. The metabolic activity in BACTEC showed an immediate dose-response-relatcd decline to a maximum of 50% of the control activity after exposure to 6.3 x 104 erg/cm2. Mouse foot pad studies showed a similar dose-response pattern. Effective-dose determinations based on metabolic or foot pad data wcrc similar. UV doses of 3.52 x 104 erg/cm2 resulted in an average 50% killing, and 7.73 x 104 erg/cm2 killed 84% of the M. leprae exposed. This UV sensitivity is similar to that reported for M. tuberculosis. UV sterilization and disinfection practices suitable for M. tuberculosis are likely to be equally effective for M. leprae.