Long-term incidence of tuberculosis among migrants according to migrant status: a cohort study

Migrants account for the majority of tuberculosis (TB) in TB low incidence countries in Western Europe. The long-term risk of TB across migrant groups following migration might be influenced by migrant status, but this is not well described. This study investigates the long-term risk of TB across migrant groups according to duration of residence and migrant status. A cohort study included all migrants ≥ 18 years who obtained residency in Denmark from 01.01.1993 to 31.12.2015. Migrants were grouped based on legal status of residency: i) asylum seekers, ii) quota refugees, iii) family reunified to Danish/Nordic citizens, iv) family reunified to immigrants, v) family reunified to refugees. TB incidence rates (IR) were estimated by Poisson regression analyses. We included 146,257 migrants. Migrants had a TB IR of 117/100.000 PY (95 % CI 113-123) in the entire follow-up. There was a general trend of initial high TB IR during the first years of residence followed by only a gradually decline in TB IR for all migrant groups. Especially asylum seekers, family reunified to refugees and quota refugees had markedly high TB IR the first 3 years of residence and although followed by a decline, TB IR remained high for several years. All groups experienced high initial TB IR, which declined only gradually following arrival. Particular asylum seekers, family reunified to refugees and quota refugees had high risks at arrival and for several years suggesting that screening programmes for these specific at-risk groups should be strengthened. In most European countries the focus is on arrival screening for active TB but our study underlines the important awareness of migrants TB risk many years after immigration