Detection of lepromatous leprosy patients shedding M. leprae in nasal droppings by enzyme immunoassay.

Enzyme immunoassays (EIAs) for detection of lepromatous leprosy (LL) patients harbouring M. leprae in nasal mucosa are described. One EIA measures IgM antibodies against the synthetic disaccharide (ND-BSA) residue of phenolic glycolipid I of M. leprae, whereas the other titrates primarily IgG antibodies against sonicate supernatant antigens of Mycobacterium w. (M.w.). Fifty coded leprosy sera were analysed by EIAs under a double blind code. Amongst the 20 LL patients with positive nasal smear, 18 (90%) were positive in EIA based on ND-BSA, in comparison to 19 (95%) in EIA using M.w. antigens. The assays can be performed on fresh serum samples or on blood samples collected on filter paper discs. These assays can be useful for leprosy control programmes.