A clinical and immunological study of four babies of mothers with lepromatous leprosy, two of whom developed leprosy in infancy.

One hundred thirteen women and 27 healthy controls were studied throughout pregnancy, at delivery, and followed up with their babies during lactation. Thirty-eight of the mothers with lepromatous leprosy were found to have solid-staining bacilli in skin smears or biopsies, and hence were considered potentially highly infectious to their unborn children by hematogenous spread via the placenta. Two babies of mothers within this group were diagnosed as having leprosy on clinical and histological grounds. A third baby could well have had leprosy, but the case was not proven. The fourth baby did not have leprosy and, although it did have ringworm, was thus deemed to be a reasonable control. The leprosy skin lesions were first observed at a special followup clinic when the children were between the aged of 9 and 17 months. The demonstration of IgA and IgM anti-M. leprae antibodies in cord sera was taken as an indication of intrauterine immunologic stimulation, and hence transplacental transmission of M. leprae. The two babies with proven leprosy showed an early and significant increase in serum IgA and in particular serum IgM anti-M. leprae antibody activity. A third baby, suspected of having leprosy but in whom the diagnosis was not proven, showed a similar but less marked increase in serum IgA and IgM activity. The fourth baby showed no such rise in anti-M. leprae activity. A decrease in serum IgG anti-M. leprae antibody activity could be demonstrated in one of the babies with leprosy after healing of the leprosy lesions, but not in the second baby.