Latent tuberculosis infection is prevalent among socially marginalised citizens in Aarhus, Denmark.

Introduction: Even in low-incidence countries, tuberculosis (TB) is common among socially marginalised people. Latent tuberculosis infection (LTBI) comprises a reservoir for future disease, and screening for LTBI and TB in these groups aids in the prevention and early detection of TB.
Methods: We performed a screening for LTBI with interferon gamma release assay (IGRA) testing, and TB screening with sputum smear examination at four shelters and four additional locations in a Danish urban area. Additionally, shelter volunteers were offered examination.
Results: A total of 145 subjects were tested; 124 with sputum smear and 100 with IGRA. Overall, 13 (13%) had LTBI, and one (0.8%) had smear-negative, culture-positive, non-cavitating TB. Among 107 socially marginalised citizens, persons of Greenlandic origin had significantly more LTBI (40.0%) than Danish subjects (9.1%) (odds ratio (OR) = 6.67 (range: 1.55-28.63)), and other ethnicities had an intermediate prevalence of LTBI (18.2%) (OR versus Danish subjects = 2.22 (range: 0.35-14.06)). A total of 38 shelter volunteers were also included; IGRA was performed in 30 of those and one (3.33%) had LTBI.
Conclusions: Our results confirm that a screening approach may reveal early cases of active TB. LTBI is common among the socially marginalised people, but varies substantially with ethnic origin.
Funding: T-spot.TB kits were provided by Oxford Immunotec.
Trial Registration: not relevant.