[Type 1 reaction in leprosy: characteristics and association with hepatitis B and C viruses].

Type 1 reaction or reversal reaction is an acute inflammatory episode in the skin and peripheral nerves that is found in up to 30% of leprosy patients and commonly causes physical disabilities. Multidrug chemotherapy and viral infections are associated risk factors. In this study, 620 leprosy patients were evaluated. Reversal reactions were diagnosed in 121 cases (19.5%) and were most frequently found in borderline patients (48%). Starting on multidrug chemotherapy was considered to be a risk factor for reversal reaction: 52% of the cases presented their first episode at this time. Neuritis was found in 73% of the cases. The presence of hepatitis B or C virus was documented in 9% of the 55 patients with reversal reaction, while it was not detected in any of the 57 patients without reaction (p = 0.026, Fisher's exact test). This suggests that these agents may have a role as risk factors for developing reversal reactions.