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The use of short-course chemotherapy in silicotuberculosis in the goldmining industry in South Africa is described in a comparative trial of 94 cases of silicotuberculosis and two matched-pair control groups with pulmonary tuberculosis only. The theoretical and practical considerations of short-course chemotherapy are discussed. It is concluded that this is an effective means of treatment for pulmonary tuberculosis in patients with silicosis as well as in patients with pulmonary tuberculosis only, irrespective of previous exposure to silica dust. There are no valid reasons why the basic tenets of short-course chemotherapy for the treatment of pulmonary tuberculosis should not apply in silicotuberculosis.

This report describes the development of alveolar silico-lipoproteinosis complicated by Mycobacterium kansasii infection in a previously healthy man who worked as a sandblaster. Alveolar silico-lipoproteinosis is a rare disease that usually is fatal within 1 year of onset of symptoms. There is a high incidence of mycobacterial infection, half being caused by atypical organisms.

Together with the synthesis of specific antibodies and autoantibodies, effects of cellular allergy, such as damage to neutrophils, agglomeration of leukocytes and inhibition of migration of leukocytes with tuberculin and isologous pulmonary antigen were established in patients with silicosis and silicotuberculosis. Autoallergy becomes manifest already in the "pre-roentgenological" stage of development of silicosis; in silicotuberculosis it correlates with the stage of the specific process. In both silicosis and silicotuberculosis, it includes elements of immediate and delayed hypersensitivity. In clinical practice, allergic reactions of leukocytes with tuberculin can be of assistance in determining the stage of the specific process and in differential diagnosis of silicosis and silicotuberculosis.

Two subjects had silicosis complicated by tuberculosis. In both patients, there was a relapse of the tuberculosis after chemotherapy was discontinued, in one case after 13 years of therapy with isoniazid and p-aminosalicylic acid. It would appear that the risk of tuberculosis in subjects with silicosis persists for life, and the suggestion is made that chemotherapy should be continued indefinitely.

Pneumoconiosis from the carbon-copper-silica rods of film projector arc lamps is a relatively rare disease. There follows a description of a family in which the father and two sons developed radiographic changes after many years working as projectionists in New South Wales.

Comparative studies were performed, of changes of serum proteins and IgG, IgA and IgM immunoglobulins in workers exposed to silicogenic dust. Depending on their response to tuberculin testing (2 U of PPD) these subjects were classified in negative and hyperergic. In both groups there was found a decreased albumin concentration in the serum and high alpha-2 globulin. In hyperergic subjects there was noted a slight increase of beta globulins and a significant rise in the titer of gammaglobulins. Immunoglobulins G showed a significant rise in hyperallergic subjects and slightly decreased in tuberculin negative ones, without attaining a level of immunologic deficiency. In both groups IgM immunoglobulins were significantly lowered, while IgA immunoglobulins were occasionally increased, although there was no positive correlation with tuberculin allergy. In three cases there was a slight IgA deficiency.

Dermatoglyphic investigations conducted by the authors made it possible to demonstrate a genetic predisposition to occupational diseases, in particular, to silicosis and silicotuberculosis. Methods based on the mathematical theory of pattern recognition were used for multifactor analysis of the data. It was shown that complex evaluation of 10 dermatoglyphic indices gave a reliable prognosis of the risk of the above two kinds of disease due to silica dust. The dermatoglyphic patterns which predict predisposition to simple silicosis or to silicotuberculosis were found to differ significantly.

The results were analysed, of the results obtained by the associated treatment with rifampicin and etambutol 2/7 for at least 6 months in 53 patients with silico-tuberculosis and positive bacteriologic tests. Only two of the patients in the group were in the 1-st stage of silicosis while half of the patients had cavities. Also 50% of the patients had strains showing resistance to various drugs. Only five of the patients did not receive chemotherapy before the start of the study. Immediate favourable bacteriological results were noted in 84.9% of the cases and late positive results represented 54.7%, while radiologic improvement was noted in 33.9% of the cases. The percentage of good results was higher in patients without cavities but it was not influenced by the stage of silicosis development.

A case of 70-year old male manifesting a simultaneous adenocarcinoma, malignant lymphoma and silicotuberculosis in the same lung has been reported. The patient, who had worked as a miner for 24 years and had been treated for silicosis 11 years previously, was found to have a new, abnormal shadow during a routine chest X-ray. Later, sputum cytology revealed the adenocarcinoma. He was treated with chemotherapy, but died 24 months later, his death attributed to lung cancer, complicated with respiratory insufficiency and weakness. An autopsy confirmed the presence of an adenocarcinoma and silicotuberculosis, and a histological examination revealed the coexistence of malignant lymphoma in the same lung.

In spite of a decreasing number of new cases of silico-tuberculosis even today there still remains a serious complication of silicosis. The job of radiology is to recognise the disease, evaluate the course of the disease during therapy and classify the disease for compensation purposes. Due to the pathogenetic and pathomorpohologic similarities of silicosis and tuberculosis, it is often difficult and sometimes even impossible to recognise the presence of tuberculosis in cases of silicoses or to identify and isolate the TB component in silicotuberculosis. Careful consideration of all radiological and clinical parameters improves the accuracy of diagnosis. Since the radiographic examination provides the only method of evaluating the morphologic state of the disease, radiology will keep its central position in the diagnosis of silicotuberculosis.

In some countries extensive research is carried out on preventing tuberculous disease by administration of INH. In GDR since about 1960 chemopreventive measures were taken in cases of silicosis and silicotuberculosis too. More than 2000 patients of the Magdeburg Pneumoconiosis Center were followed-up from 1960 to 1969. The high risk of tuberculous disease of 21% in the group of silicosis patients without administration of INH could be reduced to 14% after preventive administration of INH. However, such clear effects were observed only under optimal conditions, that is sufficient dosage, duration and reliability of treatment. On the base of these results and other publications patients with silicosis with and without tuberculous residues should be included into the programmes of preventive chemotherapy of the chest clinics.