Silicosis and Silicotuberculosis Among Small Scale Gemstone Miners in Northern Tanzania

NCT06403800 | Recruiting

• 1 other identifier: 22IC7870
• Study Type: observational
• Target: 1,400
• Locations: 1 country
• Sites: 1

Brief Summary

Artisanal, small-scale mining (ASM) is a large and essential component of the world's economy. Despite attendant risks, there is little research into risks to the health of artisanal miners. The tanzanite gemstone is mined exclusively in Northern Tanzania, in deep shafts using ASM techniques. There is concerning evidence that the burden of silicosis and tuberculosis (TB) amongst miners is high. In addition to miners' personal risks, there is concern that a high rate of silicotuberculosis may hamper community control of TB. Our primary aim is to measure the rate of silicosis progression among tanzanite miners. Our secondary aims include measuring the prevalence of TB among miners, describing TB transmission patterns in miners and the community, and assessing rates of 'catastrophic' economic loss amongst miners. To do this, the investigators propose two studies. First, the investigators will establish a prospective cohort of 410 small scale tanzanite miners and record symptoms, respiratory function including spirometry, chest radiography, and prevalence of TB and Human Immunodeficiency Virus (HIV) infection over an 18-month period. Second, the investigators will utilize an ongoing community-based TB screening program to perform a cross-sectional survey of TB prevalence among miners and community members. To assess TB transmission, the investigators will collect epidemiological data and perform whole genome sequencing (WGS) on positive Mycobacterium tuberculosis (MTb) culture samples. Given the lack of research and large global ASM workforce, 1 million of whom are in Tanzania, the results of this study will assist in the development and introduction of interventions to reduce the risks to respiratory health of artisanal mining in Tanzania and elsewhere; and provide ample scope for future work.

Conditions

Silicosis; Tuberculosis; Silicosis; With Tuberculosis

Keywords

Occupational Lung Diseases; Epidemiology; Respiratory; Infection; Tuberculosis; Silicosis

Outcome Measures

Primary Outcomes (1)

• Change in chest radiography

  Rate of change of the ILO classification of pneumoconioses among cohort participants

  18-months

Secondary Outcomes (6)

• Silicosis prevalence at baseline

  Baseline

• TB prevalence at baseline

  Baseline

• Clustering of TB cases

  18-months

• Measurement of 'catastrophic' economic loss

  18-months

• Use of C-reactive protein as a screening aid for TB

  Baseline

Study Arms (2)

Cross-sectional study

In the cross-sectional study group, we will enroll approximately 1400 miners and community members from an ongoing community-based, screening program, which is led by Kibong'oto Infectious Diseases Hospital (KIDH), and from incident TB cases from the local Mererani health centre and KIDH clinic.

Other: No intervention

Cohort group

We will enroll the prospective cohort group of 410 small-scale tanzanite miners from within the cross-sectional study group (nested). They will be sampled from specific mines chosen by a random stratified sample of mines.

Other: No intervention

Interventions

No intervention OTHER

No intervention

Cohort group; Cross-sectional study

Eligibility Criteria

• Age: 18 Years+
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Tanzanite mines are near Mererani, Simanjaro District, Northern Tanzania. The district population is 178,683, with 13,450 in Mererani. Recent data suggests Mererani's population is around 18,300 due to regional growth. About 100 active licenses exist, with each mine employing 70 to 90 miners, totaling around 9,000 miners; earlier estimates were higher at 15,000. Healthcare is provided by Kibongo'oto Infectious Diseases Hospital, 60 km away, with one other clinic offering TB services. Recruitment for our survey is from a TB screening program, offering free CXR and Xpert tests via a mobile clinic rotating. We plan to include 5-10 mines in the study, focusing on diverse roles and exposures.

You may qualify if:

• Age \> 18 years
• Ability to provide informed consent
• Miner or community member (defined as all individuals not directly involved in mining)
• HIV positive and negative individuals
• Age \> 18 years
• Ability to provide informed consent
• Current miner in an artisanal, small-scale tanzanite mine that is part of this study
• Male
• Mine exposure starting \<10 years ago
• HIV positive and negative individuals

You may not qualify if:

• \- Plans to move away from area in next 18 months

Sponsors & Collaborators

• National Heart and Lung Institute: lead
• Kibong'oto Infectious Disease Hospital, Tanzania: collaborator

Study Sites (1)

Kibong'oto Infectious Diseases Hospital

Sanya Juu, Kilimanjaro, PO Box, Tanzania

RECRUITING

Related Publications (6)

• Howlett P, Mousa H, Said B, Mbuya A, Kon OM, Mpagama S, Feary J. Silicosis, tuberculosis and silica exposure among artisanal and small-scale miners: A systematic review and modelling paper. PLOS Glob Public Health. 2023 Sep 21;3(9):e0002085. doi: 10.1371/journal.pgph.0002085. eCollection 2023.

  PMID: 37733799 BACKGROUND

• Dennis E, Mussa H, Sanga MP, Howlett P, Nyakunga G. Silicosis and silicotuberculosis among respiratory hospital admissions: A cross-sectional survey in northern Tanzania. Afr J Thorac Crit Care Med. 2023 Sep 19;29(3):10.7196/AJTCCM.2023.v29i3.269. doi: 10.7196/AJTCCM.2023.v29i3.269. eCollection 2023.

  PMID: 37970570 BACKGROUND

• Mbuya AW, Mboya IB, Semvua HH, Msuya SE, Howlett PJ, Mamuya SH. Concentrations of respirable crystalline silica and radon among tanzanite mining communities in Mererani, Tanzania. Ann Work Expo Health. 2024 Jan 8;68(1):48-57. doi: 10.1093/annweh/wxad062.

  PMID: 37824745 BACKGROUND

• Rees D, Murray J. Silica, silicosis and tuberculosis. Int J Tuberc Lung Dis. 2007 May;11(5):474-84.

  PMID: 17439668 BACKGROUND

• Ehrlich R, Murray J, Rees D. Subradiological silicosis. Am J Ind Med. 2018 Nov;61(11):877-885. doi: 10.1002/ajim.22909. Epub 2018 Sep 21.

  PMID: 30239033 BACKGROUND

• Ehrlich R, Akugizibwe P, Siegfried N, Rees D. The association between silica exposure, silicosis and tuberculosis: a systematic review and meta-analysis. BMC Public Health. 2021 May 20;21(1):953. doi: 10.1186/s12889-021-10711-1.

  PMID: 34016067 BACKGROUND

Biospecimen

Retention: SAMPLES WITH DNA

Sputum samples for MTb culture and MTb DNA extraction Whole blood samples for haematology Serum samples for biochemistry and serum save

MeSH Terms

Conditions

Silicosis; Tuberculosis; Infections

Condition Hierarchy (Ancestors)

Pneumoconiosis; Lung Diseases, Interstitial; Lung Diseases; Respiratory Tract Diseases; Lung Injury; Occupational Diseases; Mycobacterium Infections; Actinomycetales Infections; Gram-Positive Bacterial Infections; Bacterial Infections; Bacterial Infections and Mycoses

Central Study Contacts

Patrick J Howlett, MB ChB

CONTACT

+447793198119; patrick.howlett@gmail.com

Bibie N Said, MD

CONTACT

+255 718 762 991; bibiesd90@gmail.com

Study Design

• Study Type: observational
• Observational Model: OTHER
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Doctor Clinical Research Fellow

Study Record Dates

• First Submitted: May 3, 2024
• First Posted: May 8, 2024
• Study Start: March 11, 2024
• Primary Completion: October 1, 2025
• Study Completion: December 1, 2025
• Last Updated: May 16, 2024

Record last verified: 2024-05

Locations

TA (1)