Epidemiological aspects of relapses in leprosy.

Life table methods in which the cumulative probability of relapse in successive periods is calculated are preferable to the presentation of overall relapse rates. Their use facilitates the comparison of relapse rates and trends from different studies independent of duration of follow-up. Results from various studies including data from Malawi indicate that, (1) unlike after dapsone monotherapy, the cumulative probability of relapse in multibacillary patients is near to zero after WHO/MDT if strict definitions of relapse are used and, (2) the cumulative probability of relapse may approach 5% in paucibacillary patients 10 years after completion of WHO/MDT. On the whole, the epidemiological relevance of relapses is insignificant and future treatment regimens should be evaluated concerning their efficacy in preventing disabilities rather than relapses.

Efficacy of BCG vaccine against leprosy and tuberculosis in northern Malawi

Protection afforded BCG vaccines against tuberculosis and leprosy varies widely between different populations. In the only controlled trial which assessed protective efficacy of BCG (Danish and Pasteur strains) against both diseases; there was slightly more protection against leprosy than against tuberculosis. Protection was estimated at 50 percent or greater against leprosy; and there was no evidence for lower protection against multibacillary than against paucibacillary disease. There was no statistically significant protection by BCG against tuberculosis in this population