An evidence and reasoning based differential diagnosis of a case of leprosy reinfection from reaction and relapse.

Leprosy is caused by Mycobacterium leprae (M. leprae) and is unique in terms of the chronicity of the disease and its prolonged treatment protocol. Even after the introduction of multidrug therapy (MDT) by World health organization (WHO), large numbers of new cases (nearly 200,000) of leprosy are reported yearly, indicating active transmission, especially in developing countries. Recurrent clinical manifestations after MDT can occur due to leprosy reactions, relapse or reinfection. It is very difficult to differentiate reaction, relapse and reinfection. Here we categorized a recent case of reoccurrence of leprosy as reinfection by differentiating it from reaction and relapse based on evidence and by analysing the clinical data of the patient.