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Routes of M. tuberculosis transmission among merchant seafarers
Henrik L Hansen1, Peter Henrik Andersen, Troels Lillebaek
1Medical Office of Health, Vejle County, Denmark. hlhansen@dadlnet.dk
Scandinavian Journal of Infectious Diseases
|September 30, 2006
Summary
Tuberculosis (TB) poses a risk to seafarers, with this study finding most infections likely acquired ashore, not onboard ships. DNA fingerprinting revealed limited M. tuberculosis transmission among multicultural crews.
Area of Science:
- Epidemiology
- Public Health
- Microbiology
Background:
- Tuberculosis (TB) has historically impacted seafarer populations.
- Understanding contemporary TB transmission routes among merchant mariners is crucial for occupational health.
Purpose of the Study:
- To assess the current prevalence of tuberculosis (TB) in merchant seafarers.
- To identify the primary transmission pathways of Mycobacterium tuberculosis (M. tuberculosis) in this demographic using DNA fingerprinting.
Main Methods:
- Utilized a Danish database of culture-positive TB cases (1992-2003) linked with seafarer employment records.
- Employed DNA subtyping (fingerprinting) to analyze M. tuberculosis strains from identified cases.
- Calculated TB risk ratios and incidence rates per person-years at sea.
Main Results:
- Identified 64 culture-positive TB cases among seafarers, with a higher risk observed in males (1.51).
- Determined that only a small fraction of cases (2 likely, 5 possibly) were potentially shipping-related.
- Calculated a low incidence of 0.09 cases per 1000 person-years at sea for shipping-related TB.
Conclusions:
- The excess risk of TB among Danish seafarers is predominantly attributed to infections acquired in Denmark, not at sea.
- Despite diverse crews from high-incidence regions, M. tuberculosis transmission aboard modern vessels or during shore leave appears limited.
- Occupational health strategies should consider onshore risk factors for TB in seafarers.
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