Role of paucibacillary leprosy in the transmission of disease

The objective of this study was to establish that paucibacillary leprosy also carried increased risk of infection to the community. All members of 100 families with an index paucibacillary case were clinically, bacteriologically and immunologically examined. The "comparison" group was sampled from suspect register. Fifty-six cases occurred among 944 contacts of index paucibacillary cases; of these, four were multibacillary and 52 were paucibacillary. In the "comparison" group, two contacts out of 760 developed paucibacillary leprosy. This difference, between the two groups, was statistically significant. All the 56 cases in the index case families were under 20 years of age; and 50 of them were aged under 15 years. Male/female ratio was 2.1:1. Of the 56 cases, 28 shared the same bed with the index patient, 20 shared the same room and eight lived in the same house. Lepromin positivity rate was higher in "comparison" families (92.2%) than in index case families (74.6%), the difference being statistically significant (x = 6.09, P < 0.001). Contacts of index case families, therefore, were immunologically at higher risk than contacts of "comparison" families.