Epidemiological characteristics of leprosy reactions: 15 years experience from north India.

A retrospective analysis of patient's leprosy clinic records at PGIMER, Chandigarh, India for the period 1983 to 1998 was undertaken to study the frequency, time of onset, and risk factors for leprosy reactions. Of the 2600 cases analyzed, 1494 were multibacillary and 1106 had paucibacillary disease. Presentation with reaction was common with 30.9% of our patients having reactions at the time of first visit. The incidence of reversal reaction (RR) was highest during 6 to 12 months after starting multi-drug therapy (MDT), thereafter declining gradually. Late RR occurred in 9.5% of all cases and was noted up to 7 years after treatment. Female gender, widespread disease, and multibacillary disease were identified as risk factors for RR. Erythema nodosum leprosum (ENL) reactions were noted to occur mostly during second or third year after starting MDT. Of the total number of patients who experienced ENL, 64.3% had recurrent episodes which continued for up to 8 years after the start of treatment. Lepromatous leprosy, female gender, and high Bacterial Index (>/=3) were recognized as risk factors for developing ENL. Occurrence of recurrent and late reactions, even though of mild severity, highlights the importance of recognizing and treating them promptly to prevent or reduce morbidity, complications, and further deterioration in the disability status. Although it is hoped that leprosy will have been eliminated at all levels by 2005, the recognition and management of these reactions will continue to be the most essential/significant task in the post elimination era.