Drug-resistant M leprae.
Dapsone was used as a single drug to treat leprosy, and secondary resistance soon developed, greatly reducing its effectiveness. Multidrug therapy has been used successfully since 1982, and until now, only a few sporadic cases of rifampicin resistance have been reported. Surveillance is needed to make sure that chemotherapy for leprosy remains effective for the foreseeable future. This review is based on reports from the annual drug resistance surveillance meetings convened by the World Health Organization and related literature. Very few cases of rifampicin resistance are currently known globally, except for a small group of cases in a former leprosy colony in Brazil. A low level of ofloxacin resistance has been found, especially in India. A larger number of patient samples should be tested each year. The results give grounds for cautious optimism, although the number of samples tested should be significantly increased. Possible foci of rifampicin resistance near former leprosy colonies in Brazil should be further investigated.