LEPROSY TRANSMISSION AND MUCOSAL IMMUNITY - TOWARDS ERADICATION

The declining prevalence of leprosy has not been matched by a declinin g incidence. Widespread adoption of multiple drug therapy (MDT) in clo sely monitored control programmes has not prevented transmission of My cobacterium leprae. Despite the rarity of lepromatous patients, most o f those Living in endemic areas have immunological evidence of exposur e to M. leprae. This paradox could be explained if, for many such indi viduals, infection was transient, did not result in disease developmen t, but did allow the transmission of infection to other individuals. T here is increasing evidence from nasal PCR studies that such sub-clini cal transmission may exist and that mucosal immune responses to M. lep rae may develop during resolution of initial infection. Sub-clinical i nfection appears to occur in clusters and may require close contact ov er a prolonged period for optimal transmission. Control of transmissio n may be feasible through identification and treatment of individuals within infection clusters, allowing progress towards the eradication o f leprosy.