Prevention of transmission of leprosy: The current scenario

With the worldwide implementation of WHO multidrug therapy in the 1980s, the global burden of leprosy has decreased. However, the annual new case detection rate around the world has remained nearly static over the past decade with India, Brazil, and Indonesia contributing the majority of these new cases. This has been attributed to the ongoing transmission of Mycobacterium leprae from existing untreated cases and partly to the intensive new case detection programs operative in endemic areas. The WHO has called for a "global interruption of transmission of leprosy by 2020". Targeted chemoprophylaxis of contacts may help bring down the number of new cases. The single-dose rifampicin currently in use for post-exposure prophylaxis (PEP) has limitations and so newer antileprosy drugs and regimens have been trialed for chemoprophylaxis. BCG re-vaccination in combination with chemoprophylaxis for the prevention of leprosy transmission has not been very encouraging. The use of the anti-phenolic glycolipid-1 (PGL-1) antibody test to detect subclinical cases and administer targeted chemoprophylaxis was unsuccessful owing to its low sensitivity and technical difficulties in a field setup. There is a pressing need for newer multidrug chemoprophylactic regimens using second-line antileprosy drugs. The Netherlands Leprosy Relief has proposed an enhanced PEP++ regimen. A simple but highly sensitive and specific serological test to detect subclinical cases at the field level needs to be developed. Although there are a number of challenges in the large-scale implementation of strategies to halt leprosy transmission, it is important to overcome these in order to move towards a "leprosy-free world."