Does MDT arrest transmission of leprosy to household contacts?

The multidrug therapy program with the World Health Organization (WHO)-recommended treatment (WHO/MDT) regimens has given the hope of early case detection and rendering a leprosy patient, especially a multibacillary (MB) patient, noninfectious within a short period of time. Hence, the duration of exposure for household contacts to infection is expected to be remarkably less when compared to exposure to MB leprosy patients on dapsone monotherapy. A total of 1661 household contacts of skin-smear-positive leprosy patients were recorded from 1984 to 1994. Follow up of these individuals [8403 person-years at risk (PYR)] revealed that the incidence of leprosy was 7.7 per 1000 PYR, which was 8 times more than that of the general population. The risk was more if there was a coprevalent case in the family. The incidence of leprosy declines from the third year of surveillance onward, and declines more so in children. Although disease transmission should have been arrested as soon as the index case was started on MDT, the incidence of leprosy among the household contacts was still high when compared to that of the total population. Effective intervention needs to be introduced to reduce the risk of contacts developing leprosy.