Clinical features and diagnosis of relapses in leprosy.

1. The definition of relapse as "occurrence of new signs and symptoms of the disease during the period of surveillance or thereafter in a patient who successfully completes an adequate course of multidrug therapy" accommodates the current policy of releasing patients even when there are clinical and bacteriological signs of activity after fixed duration treatment. 2. The predisposing cause of relapse in the persistence of live M. leprae in various tissues in MB leprosy and in the nerve in PB leprosy. 3. The precipitating causes of relapse include (a) inadequate therapy due to miscategorization of MB cases as PB when there are solitary or few MB lesions since skin smear examinations for AFB are not routinely done in PB cases. (b) Previously sulphone treated LL cases inactive for more than two years are not included for MDT. Relapses commonly seen in NLEP units are in such cases. (c) Multiple skin and nerve lesions in PB leprosy. (d) Pregnancy and lactation. (e) Mental depression which downgrades immunity. (f) HIV infection. 4. There may be a change in type on relapsing, PB cases relapsing as MB and MB cases relapsing as PB. 5. Criteria for diagnosis of relapse are: increase in the extent of lesions, infiltration and erythema, fresh skin and nerve lesions, positive skin smears for AFB in previously negative cases; and in bacteriologically positive cases during surveillance, an increase in BI by two logs at any site over the previous BI in two successive examinations. 6. Relapses are but too often diagnosed as reversal reactions inspite of the absence of symptoms and signs of acute inflammation to the detriment of patients; a course of steroid therapy which is administered to these patients on the diagnosis of reversal reaction does not halt the progress of the disease especially in the nerve, resulting in disability.