Silico-tuberculosis: An updated review.

Silico-Tuberculosis (silico-TB) is a severe combination of tuberculosis and silicosis, caused by occupational exposure to fine crystalline silica dust, which has become a global health concern. This comprehensive review compiles the updated knowledge regarding pathophysiology, clinical manifestations, important diagnostic techniques, treatment aspects, and challenges in understanding silico-TB. The review compiles the disease's history and epidemiology, highlighting a lack of data owing to poor monitoring and healthcare particularly in low- and middle-income countries like India. Further weak safety regulations, lack of preventative measures, and inadequate education increase the rates of silico-TB. The pathophysiology shows how silica particles impair the immune system and stimulate Th2 cells and M2 macrophages, which exacerbate TB, while inhibiting Th1 cells and M1 macrophages, which fight against the disease. Subsequently, it can be difficult to distinguish current TB from pre-existing silicosis. In cases where sputum and X-ray results are negative, chest CT scans may be helpful since radiographic screening identifies TB earlier than sputum assessment. Isoniazid, rifampicin, or both minimize the risk of active tuberculosis in people with silicosis. Consistent anti-tuberculosis drug therapy is recommended for 8-9 months to stop recurrence. The assessment recommends integrating silicosis and TB control initiatives to fight this combined health issue.

Mixed methods study on latent tuberculosis among agate stone workers and advocacy for testing silica dust exposed individuals in India.

The 2021 tuberculosis (TB) preventive treatment guidelines in India included silicosis as a screening group, yet latent TB infection (LTBI) testing for silica-dust-exposed individuals is underemphasized. Focusing on an estimated 52 million silica-dust-exposed workers, particularly agate-stone workers in Khambhat, Gujarat, our study aims to estimate LTBI prevalence, identify predictors, and gather insights from TB and silicosis experts. Employing a sequential explanatory mixed-methods approach, a cross-sectional study involved 463 agate-stone workers aged ≥ 20 years in Khambhat, using IGRA kits for LTBI testing. In-depth interviews with experts complemented quantitative findings. Among agate-stone workers, 58% tested positive for LTBI, with predictors including longer exposure, type of work, and BCG vaccination. Our findings reveal a nearly double burden of LTBI compared to the general population, particularly in occupations with higher silica dust exposure. Experts advocate for including silica-dust-exposed individuals in high-risk groups for LTBI testing, exploring cost-effective alternatives like improved skin sensitivity tests, and shorter TB preventive treatment regimens to enhance compliance. Future research should explore upfront TB preventive treatment for silica-dust-exposed individuals with high LTBI prevalence and optimal exposure duration. This study underscores the urgent need for policy changes and innovative approaches to TB prevention among silica-dust-exposed populations, impacting global occupational health strategies.

Accuracy of chest x-ray screening of silica-exposed miners for tuberculosis.

BACKGROUND: The World Health Organization recommends systematic chest X-ray (CXR) screening for tuberculosis (TB) in silica-exposed workers. However, evidence on the accuracy of CXR screening in such populations is lacking. AIMS: To measure the accuracy of CXR screening for active TB in silica-exposed miners, in a population with a high prevalence of silicosis, post-TB lung disease and HIV. METHODS: A secondary analysis of data from a miner screening programme in Lesotho was undertaken. We measured the performance of CXR (in participants with and without cough) for 'abnormalities suggestive of TB' against Xpert MTB/RIF (Xpert). The sample size was 2572 and positive Xpert prevalence was 3%. RESULTS: CXR alone had high sensitivity (0.93, 95% confidence interval [CI] 0.87-0.99), but low specificity (0.41, 95% CI 0.39-0.42). Requiring cough and a positive CXR increased specificity (0.79, 95% CI 0.77-0.81), resulting in reduced sensitivity (0.41, 95% CI 0.30-0.52). There was no difference in CXR accuracy by HIV status. However, specificity was markedly reduced in the presence of silicosis (from 0.70, 95% CI 0.68-0.72, to 0.03, 95% CI 0.02-0.04) or past TB history (from 0.59, 95% CI 0.56-0.62 to 0.27, 95% CI 0.25-0.29). Throughout, positive predictive value remained very low (5%) and negative predictive value very high (99%). CONCLUSIONS: CXR screening accurately identifies TB-negative CXRs in this population, but post-TB lung disease and silicosis would result in a high proportion of Xpert-negative referrals and an increased risk of unneeded empirical treatment. Adapted screening algorithms, practitioner training and digital access to previous mining CXRs are needed.

Update on Silicosis.

Although silicosis has been an established disease with a recognized cause for more than 100 years, many workers continue to be exposed to silica and new outbreaks of disease continue to occur. This article describes some of the well-established and new exposures, including denim sandblasting, artificial stone cutting, and some forms of "coal worker's pneumoconiosis." The authors review the imaging and pathology of acute silicosis (silicoproteinosis), simple silicosis, and progressive massive fibrosis and summarize known and putative associations of silica exposure, including tuberculosis, lung cancer, connective tissue disease (especially systemic sclerosis), and vasculitis.

Systemic inflammation indices as hematological biomarkers of inflammatory response in non-silicotic workers exposed to respirable silica dust.

This cross-sectional study was performed to assess whether systemic inflammatory indices, including systemic inflammation response index (SIRI), systemic immune­inflammation index (SII), and aggregate index of systemic inflammation (AISI), can be considered as possible inflammatory markers in silica-exposed workers with no diagnosis of silicosis. We studied 371 non-silicotic workers exposed to respirable silica dust (RSD) and 1422 reference workers. The workers' exposure to RSD were assessed and the inflammatory indices were compared between subgroups of the exposed workers based on the severity and duration of exposure. Correlations between inflammatory indices and the pulmonary function parameters were investigated. Also, the receiver operating characteristic (ROC) curve and Youden index were used to determine the cut-off values of the SII, SIRI, and AISI. Significant dose-response relationships were observed between duration of exposure and all indices except monocytes and LMR. No significant interaction was observed between duration of exposure to RSD and smoking. Borderline significant correlations were observed between AISI and SIRI with forced expiratory volume (FEV1) and FEV1 to forced vital capacity (FVC) ratio. Higher AUCs were obtained for SII and AISI, respectively. The cut-off values for these biomarkers to be considered abnormal were > 348.48 for SII, > 183.78 for AISI, and > 0.768 for SIRI. Overall, the present study showed for the first time, that SII, AISI, and SIRI might be considered as available, easy-to-obtain, and non-expensive markers of inflammation in non-silicotic workers with a long duration of exposure to RSD who are at risk of developing silicosis in subsequent years.

Lung cancer risk and occupational pulmonary fibrosis: systematic review and meta-analysis.

BACKGROUND: Molecular pathways found to be important in pulmonary fibrosis are also involved in cancer pathogenesis, suggesting common pathways in the development of pulmonary fibrosis and lung cancer. RESEARCH QUESTION: Is pulmonary fibrosis from exposure to occupational carcinogens an independent risk factor for lung cancer? STUDY DESIGN AND METHODS: A comprehensive search of PubMed, Embase, Web of Science and Cochrane databases with over 100 search terms regarding occupational hazards causing pulmonary fibrosis was conducted. After screening and extraction, quality of evidence and eligibility criteria for meta-analysis were assessed. Meta-analysis was performed using a random-effects model. RESULTS: 52 studies were identified for systematic review. Meta-analysis of subgroups identified silicosis as a risk factor for lung cancer when investigating odds ratios for silicosis in autopsy studies (OR 1.47, 95% CI 1.13-1.90) and for lung cancer mortality in patients with silicosis (OR 3.21, 95% CI 2.67-3.87). Only considering studies with an adjustment for smoking as a confounder identified a significant increase in lung cancer risk (OR 1.58, 95% CI 1.34-1.87). However, due to a lack of studies including cumulative exposure, no adjustments could be included. In a qualitative review, no definitive conclusion could be reached for asbestosis and silicosis as independent risk factors for lung cancer, partly because the studies did not take cumulative exposure into account. INTERPRETATION: This systematic review confirms the current knowledge regarding asbestosis and silicosis, indicating a higher risk of lung cancer in exposed individuals compared to exposed workers without fibrosis. These individuals should be monitored for lung cancer, especially when asbestosis or silicosis is present.

[A rare case: Erasmus syndrome and tuberculosis]. / Un caso poco frecuente: síndrome de Erasmus y tuberculosis.

We present the case of a 35-year-old male patient, sandblaster for eight years, recently diagnosed with pulmonary tuberculosis and systemic sclerosis, who was admitted with dyspnea and poor general condition. Chest X-ray showed a grade I pneumothorax, and on the chest tomography he presented confluent hyperdense masses associated with a pattern of non- specific interstitial pneumonia (NSIP), findings compatible with complicated silicosis. Due to the advanced clinical stage, neither invasive diagnostic test nor pulmonary function test could be performed. Initial treatment included placement of a pleural drainage tube, antituberculosis treatment and chronic home oxygen. The patient was referred to the interstitial disease and rheumatology departments for multidisciplinary management, although the infectious condition contraindicated the possibility of immunosuppressive treatment. The patient eventually died under palliative care. Silica inhalation is the cause of silicosis, but it is also implicated in the development of systemic sclerosis (Erasmus syndrome) and although they share a common risk factor, it is rare to find both diseases coexisting. We present the case of a young patient in whom both diseases presented aggressively, with the aim of highlighting the importance of actively searching for expositional diseases and associated conditions.

Presentamos el caso de un hombre de 35 años, arenador durante ocho años, con diagnóstico reciente de tuberculosis pulmonar y esclerosis sistémica, que ingresó por cuadro de disnea y mal estado general. Se realizó radiografía de tórax donde se evidenció neumotórax grado I, en la tomografía de tórax, también presentó masas hiperdensas confluyentes, asociadas a un patrón de neumonía intersticial no especifica (NSIP), hallazgos compatibles con silicosis pulmonar complicada. Debido al avanzado estadio clínico, no pudieron realizarse estudios diagnósticos invasivos ni estudios de función pulmonar. Como tratamiento inicial se colocó un tubo de avenamiento pleural, se realizó tratamiento antifímico y se indicó oxigenoterapia crónica domiciliaria. Se remitió al paciente a consultorios de enfermedades intersticiales y reumatología para un manejo multidisciplinario, aunque el cuadro infeccioso contraindicó la posibilidad de un tratamiento inmunosupresor. Finalmente, el paciente falleció bajo cuidados paliativos. La inhalación de sílice es la causa de la silicosis, pero también está implicada en el desarrollo de la esclerosis sistémica (síndrome de Erasmus) y aunque comparten un factor de riesgo común, es raro encontrar ambas enfermedades coexistiendo. Presentamos el caso de un paciente joven donde ambas condiciones se presentaron de manera agresiva, con el objetivo de remarcar la importancia de la búsqueda activa de las enfermedades por exposición y sus condiciones asociadas.

Association between silicosis and autoimmune disease.

PURPOSE OF REVIEW: There is a well established association between silica inhalational exposure and autoimmune disease, particularly in the context of intense exposure. We will provide in this article an update overview of new sources of silica dust exposure, with evidences of mechanisms from human and animal studies for association between silica and autoimmune diseases, their early detection of silicosis and new options for treatment. RECENT FINDINGS: New industries such as jewelry polishing, denim jean production, fabrication of artificial stone benchtops, glass manufacturing and glassware has led to re-emergence of silicosis around the world. Silicosis with long term exposure to dust containing crystalline silica has been examined as a possible risk factor with respect to several autoimmune diseases as scleroderma, rheumatoid arthritis, lupus erythematosus, and some types of small vessel vasculitis with renal involvement. The dust may act to promote or accelerate disease development, requiring some other factors to break immune tolerance or initiate autoimmunity. Autophagy, apoptosis, or pyroptosis-related signaling pathways have also been suggested to contribute to the formation of those pathways with coordination of environmental co-exposure that can magnify autoimmune vulnerability. SUMMARY: Better understanding the mechanisms that involve silica -induced autoimmune diseases may contribute to early diagnosis.

Health Screening Strategies for Artisanal and Small-Scale Miners for Tuberculosis, Human Immunodeficiency Virus and Silicosis: A Case of the USAID-Supported Kunda Nqob'iTB Project in Zimbabwe.

Artisanal and small-scale mining is characterized by excessive exposure to physical, chemical, ergonomic, psychosocial and biological hazards. There is a high burden of tuberculosis (TB), human immunodeficiency virus (HIV) infections and silicosis among artisanal and small-scale miners (ASMs). The aim of this project report is to describe lessons learned from strategies implemented to reach ASMs with screening services for TB, HIV and silicosis in Zimbabwe through the Kunda-Nqob'i TB (KNTB) project supported by the United States Agency for International Development (USAID). The intervention package for screening ASMs for TB, HIV and silicosis included service provision through two occupational health clinics at two provincial hospitals and a mobile workplace-based screening (WBS) facility at the mining sites. From 1 October 2020 to 30 September 2023, 10,668 ASMs were screened, with a high number of cases of silicosis (21%) and TB (7.4%). There was a high burden of HIV (30%) in ASMs attending the occupational health clinics. The two occupational health clinics screened 3453 ASMs, while the mobile WBS activities screened 7215 ASMs during the period. A total of 370 healthcare workers (doctors/clinical officers, nurses, environmental health technicians and district tuberculosis and Leprosy control officers) were trained on TB and the fundamental diagnostic principles of silicosis. The KNTB project has been successful in reaching out to many ASMs operating in remote and hard-to-reach mining areas. The KNTB project has brought to light the positive health-seeking behavior of ASMs operating in remote areas. The project has brought to the fore the effectiveness of multi-stakeholder engagement and collaboration in reaching out to ASMs in remote areas with health screening services. There is a high burden of TB, HIV and silicosis in ASMs. Screening for TB, HIV and silicosis using workplace-based screening and occupational health clinics is an effective strategy and should be rolled out to all areas with high artisanal and small-scale mining activity.

Analyzing the incidence of silicosis across various industries in Taiwan: a study of occupational disease surveillance by linking national-based workers' and medicoadministrative databases.

OBJECTIVES: This study aimed to establish an occupational disease surveillance system by identifying high-risk industries for silicosis in Taiwan using a national database linkage approach. METHODS: The study was based on a comprehensive analysis of benefit claims from the National Labor Insurance Research Database and medical records from the National Health Insurance Research Database between 2004 and 2020, providing coverage for more than 88.5% of the workforce and 99.9% of citizens. Silicosis was defined as having received compensation for labor insurance benefits or having received a diagnosis of silicosis (International Classification of Diseases, 10th Revision: J62 or International Classification of Diseases, Ninth Revision: 502). The study used the International Standard Industrial Classification of All Economic Activities for industry-specific classification. Cox proportional hazard models were used to compare the silicosis incidence and risk among each industry and identify high-risk industries for silicosis. RESULTS: This study analyzed 1466 cases of silicosis between 2004 and 2020 and found that 28 industries had incidence rates of over 40 cases per 100,000 workers, indicating more than double the risk of developing silicosis. Of these industries, 14 were considered high risk (relative risk of over four times). Among these, this study identified industries rarely mentioned in the past, such as wholesale of brick, sand, cement, and products, artistic creation, landscape construction, and materials recovery. Stratification by years of work experience reveals those industries such as quarrying of stone, sand, clay, and other mining, construction of buildings, landscape construction, site preparation, foundation and structure construction, building completion and finishing, manufacture of ships, boats, and floating structures, and plumbing, heat, and air conditioning installation display higher hazard ratios for individuals with <10 years of work experience. CONCLUSIONS: The current surveillance system has identified certain industries that are at a higher risk of developing silicosis, which could be used for future occupational epidemiological surveys and targeted preventive measures in these sectors.

Can Serum Chitotriosidase Levels, Immune, and Oxidative Stress Parameters Be Early Diagnostic Indicators in Patients With Silicosis?

OBJECTIVE: We aimed to evaluate the enzyme activity of chitotriosidase as a biomarker in early diagnosis silicosis and to investigate immune system response and oxidative stress caused by silica exposure. MATERIALS AND METHODS: Silicosis patients (n = 116), exposed to silica without disease (n = 76), and healthy individuals (n = 55) were included. Serum levels of chitotriosidase, proinflammatory cytokines, oxidant-antioxidant, and immune parameters were measured. RESULTS: Serum chitotriosidase enzyme levels in the silicosis group were statistically significantly higher than the exposure and control groups. Inflammatory biomarkers and 8-hydroxy-2-deoxyguanosine levels were found to be statistically significantly higher in the silicosis and exposure group compared with the controls, while superoxide dismutase and glutathione peroxidase were lower. CONCLUSIONS: Increased serum chitotriosidase level emerged as a biomarker that can not only distinguish silicosis from exposure and healthy controls but also indicate early pulmonary effects of silica.

Active Surveillance of Engineered Stone Workers Facilitates Early Identification of Silicosis: A Discussion of Surveillance of Occupational Lung Diseases.

Silicosis in workers exposed to respirable crystalline silica while fabricating engineered stone products is an emerging respiratory health issue. We describe silicosis in engineered stone workers in California and examine clinical features by the source of identification. Cases were identified passively using hospital-based patient discharge data or actively through outreach and medical testing following enforcement investigation. Outcomes were examined based on the source of case identification. We identified 18 cases diagnosed between 2006 and 2020. Cases identified passively compared to other identification methods were associated with lower percent predicted forced vital capacity (FVC) (P ≤ .01), forced expiratory volume in 1 s (FEV1) (P ≤ .01), and diffusing capacity of the lungs for carbon monoxide (DLCO) (P < .01) at the time of diagnosis and were more likely to be identified following death or lung transplant (P = .01). Our experience demonstrates delays in diagnosis and case identification when relying on passive surveillance methods. Enhanced public health surveillance systems can improve the early detection of occupational lung disease and inform future prevention policies.

Silicosis Among Immigrant Engineered Stone (Quartz) Countertop Fabrication Workers in California.

Importance: Silicosis associated with inhalation of respirable crystalline silica among engineered stone countertop fabrication workers is an emerging health concern. Objective: To describe clinical, socioeconomic, and occupational characteristics of patients diagnosed with silicosis associated with engineered stone in California. Design, Setting, and Participants: This case series included reported cases of silicosis associated with fabrication of engineered stone countertops, as identified by statewide surveillance by the California Department of Public Health (2019-2022). Data analysis was performed from October 2022 to March 2023. Exposures: Patient interviews and medical record abstractions were used to assess occupational exposure to respirable crystalline silica, including duration of work tenure and preventive measures undertaken. Main Outcomes and Measures: Demographics, clinical characteristics, health care utilization, and clinical outcomes were obtained, including vital status, hypoxia, and lung transplant. Results: This case series identified 52 male patients meeting inclusion criteria; median (IQR) age was 45 (40-49) years, and 51 were Latino immigrants. Ten (19%) were uninsured, and 20 (39%) had restricted-scope Medi-Cal; 25 (48%) presented initially to an emergency department. A delay in diagnosis occurred in 30 (58%) patients, most commonly due to alternative initial diagnoses of bacterial pneumonia (9 [30%]) or tuberculosis (8 [27%]). At diagnosis, 20 (38%) patients had advanced disease (progressive massive fibrosis) with severely or very severely reduced forced expiratory volume in 1 second in 8 (18%) and 5 (11%), respectively. Of the cases, 10 (19%) were fatal; median (IQR) age at death was 46 (38-51) years, and 6 patients (12%) were alive with chronic resting hypoxia. Eleven were referred for lung transplant: 3 underwent transplant with 1 fatality; 7 were declined transplant, with 6 fatalities; and 1 died prior to listing. Median (IQR) work tenure was 15 (10-20) years; 23 (45%) reported use of water suppression for dust mitigation, and 25 (48%) continued to fabricate stone after being diagnosed with silicosis. Conclusions and Relevance: In this case series performed in California, silicosis associated with occupational exposure to dust from engineered stone primarily occurred among young Latino immigrant men. Many patients presented with severe disease, and some cases were fatal.

[Silicosis]. / Silicose.

BACKGROUND: Silicosis is a potentially severe but preventable occupational lung disease caused by inhalation of silica particles. There is a wide application in the usage of silica especially in lesser known industries. This disease has yet not been eradicated due to insufficient application of protective measures. CASE DESCRIPTION: A 57-year-old patient presents to the pulmonary outpatient clinic with progressive dyspnea d'effort. The professional history states that he worked as a sandblaster 10 years ago. The accompanying protective measures were not properly followed by the patient at the time. The CT chest showed a nodular interstitial lung disease and silica particles were detected in the bronchial lavage conforming the diagnosis of silicosis. CONCLUSION: Early detection of silicosis is essential to prevent further lung damage and silicosis associated complications. The occupational history and radiological diagnostics are essential to confirm the diagnosis. There is no specific treatment for silicosis. Therefore prevention is better than cure.

[A systematic review of the epidemiology and clinical characteristics of artificial stone-related silicosis and dust protection].

Objective: To investigate the epidemiology, clinical characteristics, on-site dust monitoring and individual protection of the patients with artificial stone-related silicosis. Methods: In March 2022, the literature on artificial stone-related silicosis published from January 1965 to February 2022 was searched in China Journal Full-text Database, Wanfang Database, VIP Database, EMbase and PubMed. Chinese and English search terms include "silica dust""silica dust""silicosis""artificial stone""pneumoconiosis", etc. References were included according to inclusion and exclusion criteria, and data were extracted. The epidemiological characteristics, natural course of disease, workplace dust concentration and individual protection level of patients with artificial stone-related silicosis were analyzed by systematic review. Results: A total of 30 literatures were included, including 7 cohort studies, 14 cross-sectional studies, 3 case-control studies and 6 case reports. A total of 1358 patients with artificial stone-related silicosis were diagnosed from 1997 to 2020, with an average age of 41.5 years old and an average dust exposure time of 11.3 years. Among them, 36.2% (282/778) had progressive mass fibrosis or accelerated progressive silicosis at first diagnosis. Chest imaging showed diffuse small nodule shadow, pulmonary fibrosis, and silico-alveolar proteinosis. Pulmonary function showed restricted or mixed ventilation disorder with or without decreased diffusion volume. The disease progressed rapidly, with progressive mass fibrosis, respiratory failure, and even death. Patients engaged in artificial quartz stone processing, with high concentration of silica including ultra-fine particles, most of which were dry operation, lack of on-site ventilation measures and no effective personal protection. Conclusion: The artificial stone processing workers suffer from artificial stone-related silicosis due to dry cutting, lack of on-site dust removal facilities and personal protective measures, and the disease progresses rapidly, leading to poor prognosis.

Silicosis as an unusual cause of symptomatic cervical adenopathy.

A case of symptomatic cervical adenopathy is reported as a presentation of silicosis. Silicosis is one of the most important occupational health diseases worldwide caused by the inhalation of airborne silica particles. The presence of thoracic adenopathies is a common clinical feature of silicosis, cervical silicotic adenopathies on the other hand are rare and unknown to most clinicians and can therefore lead to a differential diagnostic problem. Awareness of the clinical, radiological, and histological features is key for the diagnosis.

Silicosis: Emerging Trends and How to Screen for Early Detection.

BACKGROUND: National investigations are finding silicosis in young workers. We developed a silicosis case-finding process and conducted follow-up interviews to identify emerging exposure sources. METHODS: Probable cases were identified through Wisconsin hospital discharge and emergency department data and Wisconsin lung transplant programs. Interviews were attempted with case-patients under age 60. RESULTS: We identified 68 probable silicosis cases and interviewed 4 case-patients. Occupational exposures for cases under age 60 included sandblasting, quarry work, foundry work, coal mining, and stone fabrication. Two stone fabrication workers were diagnosed before age 40. DISCUSSION: Prevention is critically important to eliminate occupational silicosis. Clinicians should obtain the occupational and exposure history to identify cases of occupational lung disease and notify public health to identify and prevent workplace exposures.