Silico-Tuberculosis

Our plain-English summary of Silico-Tuberculosis, by D.M. Brumfiel, L.U. Gardner (1937).

The study

• Authors: D.M. Brumfiel, L.U. Gardner
• Published: American Review of Tuberculosis, Volume 26 No6. December 1937
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1937 descriptive article by D.M. Brumfiel and L.U. Gardner, of the Saranac Laboratory in New York, reported no new case counts or statistics. It described silico-tuberculosis, the American term for a chronic form of tuberculosis that the authors said occurs only in silicotic lungs; South African writers used the terms differently. They described three features: onset usually in the fifth and sixth decades of life, chronicity with little toxicity, and tubercle bacilli that were difficult or impossible to find until late. They said silica reaching an old tuberculous focus could make surviving bacilli multiply, and infection could spread if the surrounding fibrous tissue was not too thick; this had been seen repeatedly in experimental animals. Very thick scar kept bacilli locked in, so sputum stayed negative. The disease practically always caused shortness of breath. The authors concluded that it is a distinct disease entity and proposed close supervision, with re-examination perhaps every three months, of workers whose routine X-rays showed characteristic or suspicious shadows. The cited paper concerns silica and does not discuss asbestos.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Descriptive commentary on the clinical and pathological features of silico-tuberculosis; no new data or statistics presented
• Who was studied: Men in the dusty trades, described in general terms. The authors refer to serial X-ray examination of thousands of such men but give no specific study group, numbers or dates.
• Exposure: Silica dust, in people with silicotic lungs. The cited paper does not discuss asbestos.
• Main results:
  • The authors described silico-tuberculosis as appearing in the later decades of life, usually the fifth and sixth
  • The authors described a strong tendency toward chronicity and a low grade of toxicity
  • According to the authors, tubercle bacilli were difficult or impossible to demonstrate until late in the disease
  • The authors stated that microscopic examination of lung tissue after death had shown the pathology of modified tuberculosis even where sputum tests were negative
  • The authors described how silica reaching the interior of an old tuberculous focus causes surviving tubercle bacilli to multiply, with infection spreading when the fibrous investment is not too thick. They said this series of events had been observed repeatedly in experimental animals.
  • According to the authors, where bacterial growth began only after a very thick zone of fibrosis had formed, the bacilli stayed held in dense scar tissue and sputum remained negative
  • The authors stated that silico-tuberculosis practically always produces shortness of breath (dyspnoea) of varying severity
• The authors' conclusion: The authors concluded that silico-tuberculosis is neither silicosis nor tuberculosis, nor a simple sum of the two, but a distinct disease entity. They urged close supervision and repeated examination of workers with characteristic or suspicious X-ray shadows.
• Limitations the authors state:
  • The authors stated that the role of the coexisting silicosis in the later clinical course was still undetermined

Topics

Medical terms in this study, explained in our Lexicon: Saranac Laboratory, Sputum.

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