An epidemic of tuberculosis with a high rate of tuberculin anergy among a population previously unexposed to tuberculosis, the Yanomami Indians of the Brazilian Amazon.

A survey of an emerging tuberculosis epidemic among the Yanomami Indians of the Amazonian rain forest provided a unique opportunity to study the impact of tuberculosis on a population isolated from contact with the tubercle bacillus for millennia until the mid-1960s. Within the Yanomami population, an extraordinary high prevalence of active tuberculosis (6.4% of 625 individuals clinically examined) was observed, indicating a high susceptibility to disease, even among bacille Calmette-Guérin-vaccinated individuals. Observational studies on cell-mediated and humoral immune responses of the Yanomami Indians compared with contemporary residents of the region suggest profound differences in immunological responsiveness to Mycobacterium tuberculosis infection. Among the Yanomami, a very high prevalence of tuberculin skin test anergy was found. Of patients with active tuberculosis, 46% had purified protein derivative of tuberculosis reactions <10 mm; similarly 58% of recent bacillus Calmette-Guérin vaccines exhibited skin test reactions <5 mm. The Yanomami also had higher titers of antibodies against M. tuberculosis glycolipid antigens (>70%) than the control subjects comprised of Brazilians of European descent (14%). The antibodies were mostly of the IgM isotype. Among the tuberculosis patients who also produced IgG antibodies, the titers of IgG4 were significantly higher among the Yanomami than in the control population. Although it was not possible to analyze T-cell responses or patterns of lymphokine production in vitro because of the remoteness of the villages from laboratory facilities, the results suggest that the first encounter of the Yanomami Indian population with tuberculosis engenders a diminished cell-mediated immune response and an increased production antibody responses, relative to other populations with extensive previous contact with the pathogen. These findings suggest that tuberculosis may represent a powerful selective pressure on human evolution that over centuries has shaped the nature of human immune responses to infection.

Relationships between titers of antibodies immunoreacting against glycolipid antigens from Mycobacterium leprae and M. tuberculosis, the Mitsuda and Mantoux reactions, and bacteriological loads: implications in the pathogenesis, epidemiology and serodiagnosis of leprosy and tuberculosis.

Analysis of cell-mediated immunity [(CMI) as judged from the Mantoux, Fernandez, and Mitsuda reactions and the presence of granulomas in biopsy material] against humoral immunity (measurements of anti-PGL-I, PGL-Tb1, and SL-IV IgG and IgM antibody titers by ELISA) were performed in selected human populations. The investigations yielded data indicating that humoral (B-cell) responses preceded protective CMI in both tuberculosis and leprosy. The B-cell responses were unrelated to (unfavorable) cell-mediated delayed-type hypersensitivity (DTH). Notwithstanding the difficulty in inferring sequential events from studies in humans, it was shown that in humoral responses there was an initial rise of specific IgM immunoglobulins that switched afterward to IgG production during subclinical tuberculosis and leprosy infections. In patent tuberculosis disease the IgM-to-IgG switch was observed in the majority of patients; in patent leprosy disease the switch was impaired in the majority of patients. The clinical, immunological, and laboratory data indicated that the B-cell responses were suppressed as protective CMI was re-established in the patients during the protracted subclinical infection. According to the data, the diagnosis of subclinical tuberculosis and leprosy may be accomplished using ELISA. The yearly risk of tuberculosis in apparently healthy persons but with significant antibody titers was estimated at 44%; the yearly risk for leprosy has not yet been established. The clinical, epidemiologic, and diagnostic implications of these findings are discussed.

Mycobacterial flora of the skin in leprosy.

The presence of mycobacteria on the skin of healthy people and in leprosy lesions has been documented previously. The present study observed the mycobacterial flora on the hands (by the hand-washing method) and fingers (by the inoculated culture medium using scraped material obtained during the preparation of slit-skin smears) in 89 untreated leprosy patients. We also evaluated the slit-skin smears from fingers for the diagnosis of leprosy. In 16 patients (17.9%) mycobacteria were cultured from scrapings and hand washings. The frequency of isolates from lepromatous (LL) leprosy cases (52.9%) was significantly higher than from tuberculoid (TT) leprosy cases (5.2%). It was observed that Mycobacterium avium and M. scrofulaceum were the only opportunistic mycobacteria isolated from multibacillary patients, and two hypotheses are discussed to explain these findings. The slit-skin smears from fingers were as satisfactory as smears from other sites for the diagnosis of leprosy, but they were less satisfactory for estimating the morphological index.

Non-cultivable mycobacteria in ulcers of the skin.

In biopsies of 54 patients suffering from chronic dermatological lesions (mostly ulcers of the skin) acid-fast bacilli were found in 14. In these 14 cases in 4 were lesions caused by M. tuberculosis, in 1 the lesion was caused by M. avium-intracellulare, in 1 the lesion was caused by M. fortuitum and in 2 the lesions were caused by non-cultivable mycobacteria (Feldmann-Hershfield ulcer?). In 2 cases the cultures were heavily contaminated, and the diagnosis remained uncertain. In the remaining 4 cases the mycobacteria were considered occasional isolates without clinical significance.

[Acid-fast bacilli in the water of the Lake of Aleixo]. / Bacilos álcool-ácido-resistentes na água do Lago do Aleixo.

The presence of acid-fast bacilli in the waters of the lake of Aleixo is recorded. This site is a hanseniasis colony. The physical-chemical environment of this lake is described by an annual cycle and it is intended to relate the quality of the water to the highest or to the lowest frequency of detected mycobacteria. It is suggested that the work in this lake system should be continued towards a more specific characterization of these microorganisms and the determination of their viability.

Bacilos alcool-acido-resistentes na agua do lago do Aleixo. / Acid-alcohol resistance bacilli in the water of the lake of Aleixo

Relata-se a presenca de bacilos alcool-acido-resistentes na agua do lago do Aleixo, local habitado por uma comunidade de hansenianos. O ambiente fisico-quimico do lago e descrito em um ciclo anual e procura-se relacionar a qualidade da agua a maior ou menor freguencia de micobacterias detectadas. Propoe-se o prosseguimento do trabalho nesse sistema lacustre, direcionado mais especificamente para a caracterizacao desses microrganismos e determinacao de sua viabilidade