Tuberculose e silicose: epidemiologia, diagnóstico e quimioprofilaxia / Tuberculosis and silicosis: epidemiology, diagnosis and chemoprophylaxis

A silicose, a mais prevalente das pneumoconioses, é provocada pela inalação de partículas de sílica cristalina. Indivíduos expostos à sílica, com ou sem silicose, apresentam risco aumentado de tuberculose e de micobacterioses não-tuberculosas. O risco de silicóticos desenvolverem tuberculose em relação a controles sadios varia de 2,8 a 39 vezes, em conformidade com a gravidade da doença de base. Têm sido estudados diferentes esquemas de quimioprofilaxia para tuberculose em silicóticos, todos com eficácia semelhante e com redução final de risco para cerca da metade em relação ao uso de placebo. São, no entanto, esquemas de longa duração, o que, acrescido dos possíveis efeitos colaterais (particularmente hepatotoxicidade), podem prejudicar a aderência. As diretrizes atuais recomendam a realização de prova tuberculínica e, se positiva, a instituição de quimioprofilaxia. São vários os esquemas possíveis, tanto em termos de drogas quanto de duração. Nossa recomendação é de que se use isoniazida na dose de 300 mg/dia (ou 10 mg/kg/dia) por seis meses para os indivíduos com silicose ou sadios com exposição superior a 10 anos, se forem reatores fortes à prova tuberculínica (induração > 10 mm). São necessários, no entanto, novos estudos para que indicações, drogas, doses e duração da profilaxia sejam definidas mais apropriadamente.

Silicosis, the most prevalent of the pneumoconioses, is caused by inhalation of crystalline silica particles. Silica-exposed workers, with or without silicosis, are at increased risk for tuberculosis and nontuberculous mycobacteria-related diseases. The risk of a patient with silicosis developing tuberculosis is higher (2.8 to 39 times higher, depending on the severity of the silicosis) than that found for healthy controls. Various regimens for tuberculosis chemoprophylaxis in patients with silicosis have been studied, all of which present similar efficacy and overall risk reduction to about one half of that obtained with placebo. Long-term regimens have potential side effects (particularly hepatotoxicity). In addition, the use of such regimens can jeopardize adherence to treatment. The current guidelines recommend that tuberculin skin tests be performed, and, if positive, that chemoprophylaxis be instituted. There are several possible regimens, varying in terms of the drugs prescribed, as well as in terms of treatment duration. We recommend the use of isoniazid at 300 mg/day (or 10 mg/kg/day) for six months for patients with silicosis, as well as for healthy patients with periods of exposure to silica longer than 10 years and strongly positive tuberculin skin test results (induration > 10 mm). Nevertheless, further studies are necessary so that indications, drugs, doses and duration of chemoprophylaxis regimens can be more properly defined.

Estudio epidemiológico de la silicosis en las minas del Perú / An epidemiological study of silicosis in the mines of Peru

This epidemiological study attempts to determine the relation that exists between environmental factors and silicosis. Evaluation studies were conducted from 1949 to 1969 primarily in mines exploiting lead, zinc, and copper. These mines are located at altitudes of more than 3,000 meters above sea level and were selected because they present data of a statistically consistent and representative nature

The writer has determined that the equation adopted by the "American Conference of Governmental Industry Hygienists" of the United States of America to explain the permissible concentration of siliceous dust in the air is not applicable in Peru, because it represents a value that exceeds by two-and-a-half to three-and-a-half times the recommended concentration. He also discards the equation formulated by A. Yataco (see the Boletín de la OPS, August, 1967)

It should be noted that silicosis is the principal occupational illness - especially characteristic of Peru - which the Peruvian miners encounter and suffer, while working in the mines which are located 4,000 to 5,000 meters above sea level. In addition to this unique situation, the Peruvian miners also differ ethnically, dietetically and socially from miners in other countries

Without doubt, the element of height reduces the partial pressure of the atmospheric oxygen conditions affecting the worker's physiological reactions, namely the ... (AU)

Silicosis con corto tiempo de exposición / Silicosis with short exposure period

A study made of 1,901 cases of silicosis, in various stages, coming from mines located at different altitudes. Of these, 763 were a micronodular form of silicosis, 295 were macronodular, 253 were confluent and 590 were silicotuberculosis. The average working period for each stage of this affection was 10 years

Of the 1,901 cases, 344 (18.1 per cent) of the patients were found to have worked for less than five years in all. Of these cases 344, or 53.5 per cent were micro and macronodular in form and 46.5 per cent were confluent, with or without infection

Studies were made of 146 and 95 cases of silicosis, in various stages, coming from nine mines in a region with a high silicosis potential. The average working period was eight years and the percentage of cases with less than five years of work was 37.7 and 6.6

This situation shows that the trend of absenteeism is different in the two regions. In 2,027 and 3,319 cases of silicosis found in the mining regions of Huancavelica, Junin and Pasco, 77.7 per cent and 0.4 per cent had a work period of more than 20 years. Thus there is not stability in mining work because of the high risk involved

The conclusion to be drawn from these percentages is that silicosis is a serious public health problem in Peru, particularly in some mining regions, not only because of high-risk environmental conditions but because of the prevalence of tuberculosis ... (AU)