Maria E. Pinardi

Immunoprophylactic trial with combined Mycobacterium Leprae/BCG vaccine against leprosy: preliminary results

In an attempt to find a vaccine that gives greater and more consistent protection against leprosy than BCG vaccine, we compared BCG with and without killed Mycobacterium leprae in Venezuela. Close contacts of prevalent leprosy cases were selected as the trial population since they are at greatest risk of leprosy. Since 1983, 29,113 contacts have been randomly allocated vaccination with BCG alone or BCG plus 6 x 10(8) irradiated, autoclaved M leprae purified from the tissues of infected armadillos. We excluded contacts with signs of leprosy at screening and a proportion of those whose skin-test responses to M leprae soluble antigen (MLSA) were 10 mm or more (positive reactions). By July, 1991, 59 postvaccination cases of leprosy had been confirmed in 150,026 person-years of follow-up through annual clinical examinations of the trial population (31 BCG, 28 BCG/M leprae). In the subgroup for which we thought an effect of vaccination was most likely (onset more than a year after vaccination, negative MLSA skin-test response before vaccination), leprosy developed in 11 BCG recipients and 9 BCG/M leprae recipients; there were 18% fewer cases (upper 95% confidence limit [CL] 70%) in the BCG/M leprae than in the BCG alone group. For all cases with onset more than a year after vaccination irrespective of MLSA reaction the relative efficacy was 0% (upper 95% CL 54%; 15 cases in each vaccine group). Retrospective analysis of data on the number of BCG scars found on each contact screened suggested that BCG alone confers substantial protection against leprosy (vaccine efficacy 56%, 95% CL 27-74%) and there was a suggestion that several doses of BCG offered additional protection. There is no evidence in the first 5 years of follow-up of this trial that BCG plus M leprae offers substantially better protection against leprosy than does BCG alone, but the confidence interval on the relative efficacy estimate is wide.

Leprosy: confirmation in the armadillo.

Bacteria isolated from lesions of lepromatoid leprosy in the armadillo were studied in comparison with Mycobacterium leprae isolated directly from human lepromatous leprosy lesions. Three methods were used to show that the bacteria from the lesions of the armadillo were identical to those of the human lesions: (i) extraction of the bacteria with pyridine and subsequent staining with various techniques, (ii) the competence in clearing bacilli (CCB) test, and (iii) the Mitsuda test.

Spheroidal bodies and globi of human leprosy

From the plasma and/or buffy coats of 80% of 38 cases of (tuberculoid and lepromatous) leprosy have been isolated in pure culture a group of spheroidal organisms (spheroidal bodies of leprosy, SPBL) showing on various media a versatility of differention ranging from naked protoplasts to globi containing acid-fast rods. The acid-fastness of the latter, like the unique acid-fastness of leprosy bacilli from lepromatous leprosy, can be extracted with C5H5 N. Inoculation of chick embryos with SPBL elicits the nodular response evoked by homogenates of lepromatous tissue. From these nodules SPBL can be recovered in pure culture. SPBL appears to be the long sought etiologic agent of leprosy.

Immunological reactions in Onchocerciasis

Abstract Precipitating antibodies against soluble antigens isolated from the filariae of O. volvulus were detected in 64% of sera tested from onchocerciasis patients, by the method of Ouchterlony. The presence of this type of antibody was not highly correlated with the presence or absence of ocular lesions. Skin-sensitizing antibody was demonstrated by passive transfer to a responsive normal individual in 15 of 19 sera so tested. Direct skin tests with microfilarial antigen were positive in 86% of a group of onchocerciasis patients and 13% of a control group, suggesting that further investigation of this type of test as an aid in diagnosis is warranted.