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Tuberculosis in migrants moving from high-incidence to low-incidence countries: a population-based cohort study of 519   955 migrants screened before entry to England, Wales, and Northern Ireland

View Article: PubMed Central - PubMed

ABSTRACT

Background: Tuberculosis elimination in countries with a low incidence of the disease necessitates multiple interventions, including innovations in migrant screening. We examined a cohort of migrants screened for tuberculosis before entry to England, Wales, and Northern Ireland and tracked the development of disease in this group after arrival.

Methods: As part of a pilot pre-entry screening programme for tuberculosis in 15 countries with a high incidence of the disease, the International Organization for Migration screened all applicants for UK visas aged 11 years or older who intended to stay for more than 6 months. Applicants underwent a chest radiograph, and any with results suggestive of tuberculosis underwent sputum testing and culture testing (when available). We tracked the development of tuberculosis in those who tested negative for the disease and subsequently migrated to England, Wales, and Northern Ireland with the Enhanced Tuberculosis Surveillance system. Primary outcomes were cases of all forms of tuberculosis (including clinically diagnosed cases), and bacteriologically confirmed pulmonary tuberculosis.

Findings: Our study cohort was 519 955 migrants who were screened for tuberculosis before entry to the UK between Jan 1, 2006, and Dec 31, 2012. Cases notified on the Enhanced Tuberculosis Surveillance system between Jan 1, 2006, and Dec 31, 2013, were included. 1873 incident cases of all forms of tuberculosis were identified, and, on the basis of data for England, Wales, and Northern Ireland, the estimated incidence of all forms of tuberculosis in migrants screened before entry was 147 per 100 000 person-years (95% CI 140–154). The estimated incidence of bacteriologically confirmed pulmonary tuberculosis in migrants screened before entry was 49 per 100 000 person-years (95% CI 45–53). Migrants whose chest radiographs were compatible with active tuberculosis but with negative pre-entry microbiological results were at increased risk of tuberculosis compared with those with no radiographic abnormalities (incidence rate ratio 3·2, 95% CI 2·8–3·7; p<0·0001). Incidence of tuberculosis after migration increased significantly with increasing WHO-estimated prevalence of tuberculosis in migrants' countries of origin. 35 of 318 983 pre-entry screened migrants included in a secondary analysis with typing data were assumed index cases. Estimates of the rate of assumed reactivation tuberculosis ranged from 46 (95% CI 42–52) to 91 (82–102) per 100 000 population.

Interpretation: Migrants from countries with a high incidence of tuberculosis screened before being granted entry to low-incidence countries pose a negligible risk of onward transmission but are at increased risk of tuberculosis, which could potentially be prevented through identification and treatment of latent infection in close collaboration with a pre-entry screening programme.

Funding: Wellcome Trust, UK National Institute for Health Research, UK Medical Research Council, Public Health England, and Department of Health Policy Research Programme.

No MeSH data available.


Related in: MedlinePlus

Cases of tuberculosis notified in migrants to England, Wales, and Northern Ireland (A), and incidence rates for tuberculosis (B), by time since entry(A) Includes 439 pre-entry prevalent cases detected between Jan 1, 2006, and Dec 31, 2012, post-entry missed prevalent cases (41 cases notified within 90 days after migration), and all tuberculosis cases (1873 cases) notified in the UK among migrants by year since migration. The error bars in (B) are 95% CIs.
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fig3: Cases of tuberculosis notified in migrants to England, Wales, and Northern Ireland (A), and incidence rates for tuberculosis (B), by time since entry(A) Includes 439 pre-entry prevalent cases detected between Jan 1, 2006, and Dec 31, 2012, post-entry missed prevalent cases (41 cases notified within 90 days after migration), and all tuberculosis cases (1873 cases) notified in the UK among migrants by year since migration. The error bars in (B) are 95% CIs.

Mentions: When all 2353 cases of tuberculosis detected both before entry and after migration were considered, most (1873 [79·6%]) were incident cases notified in England, Wales, and Northern Ireland, with fewer pre-entry prevalent cases (439 [18·7%]) and some missed prevalent cases noted with 90 days of migration (41 [1·7%]; figure 3A). The total number of tuberculosis cases in migrants declined each year since migration when prevalent cases detected at pre-entry screening (who were excluded from the cohort because they were declined medical certificates of clearance) and missed prevalent cases detected after entry were included (figure 3). Accounting for person time at risk within the cohort (and excluding pre-entry and post-entry prevalent cases) the incidence of all forms of tuberculosis was lowest in the first 12 months after migration (61 per 100 000 person-years, 95% CI 54–69), peaked in the fourth year (222, 198–249), and then gradually fell (figure 3B).


Tuberculosis in migrants moving from high-incidence to low-incidence countries: a population-based cohort study of 519   955 migrants screened before entry to England, Wales, and Northern Ireland
Cases of tuberculosis notified in migrants to England, Wales, and Northern Ireland (A), and incidence rates for tuberculosis (B), by time since entry(A) Includes 439 pre-entry prevalent cases detected between Jan 1, 2006, and Dec 31, 2012, post-entry missed prevalent cases (41 cases notified within 90 days after migration), and all tuberculosis cases (1873 cases) notified in the UK among migrants by year since migration. The error bars in (B) are 95% CIs.
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121129&req=5

fig3: Cases of tuberculosis notified in migrants to England, Wales, and Northern Ireland (A), and incidence rates for tuberculosis (B), by time since entry(A) Includes 439 pre-entry prevalent cases detected between Jan 1, 2006, and Dec 31, 2012, post-entry missed prevalent cases (41 cases notified within 90 days after migration), and all tuberculosis cases (1873 cases) notified in the UK among migrants by year since migration. The error bars in (B) are 95% CIs.
Mentions: When all 2353 cases of tuberculosis detected both before entry and after migration were considered, most (1873 [79·6%]) were incident cases notified in England, Wales, and Northern Ireland, with fewer pre-entry prevalent cases (439 [18·7%]) and some missed prevalent cases noted with 90 days of migration (41 [1·7%]; figure 3A). The total number of tuberculosis cases in migrants declined each year since migration when prevalent cases detected at pre-entry screening (who were excluded from the cohort because they were declined medical certificates of clearance) and missed prevalent cases detected after entry were included (figure 3). Accounting for person time at risk within the cohort (and excluding pre-entry and post-entry prevalent cases) the incidence of all forms of tuberculosis was lowest in the first 12 months after migration (61 per 100 000 person-years, 95% CI 54–69), peaked in the fourth year (222, 198–249), and then gradually fell (figure 3B).

View Article: PubMed Central - PubMed

ABSTRACT

Background: Tuberculosis elimination in countries with a low incidence of the disease necessitates multiple interventions, including innovations in migrant screening. We examined a cohort of migrants screened for tuberculosis before entry to England, Wales, and Northern Ireland and tracked the development of disease in this group after arrival.

Methods: As part of a pilot pre-entry screening programme for tuberculosis in 15 countries with a high incidence of the disease, the International Organization for Migration screened all applicants for UK visas aged 11 years or older who intended to stay for more than 6 months. Applicants underwent a chest radiograph, and any with results suggestive of tuberculosis underwent sputum testing and culture testing (when available). We tracked the development of tuberculosis in those who tested negative for the disease and subsequently migrated to England, Wales, and Northern Ireland with the Enhanced Tuberculosis Surveillance system. Primary outcomes were cases of all forms of tuberculosis (including clinically diagnosed cases), and bacteriologically confirmed pulmonary tuberculosis.

Findings: Our study cohort was 519 955 migrants who were screened for tuberculosis before entry to the UK between Jan 1, 2006, and Dec 31, 2012. Cases notified on the Enhanced Tuberculosis Surveillance system between Jan 1, 2006, and Dec 31, 2013, were included. 1873 incident cases of all forms of tuberculosis were identified, and, on the basis of data for England, Wales, and Northern Ireland, the estimated incidence of all forms of tuberculosis in migrants screened before entry was 147 per 100 000 person-years (95% CI 140–154). The estimated incidence of bacteriologically confirmed pulmonary tuberculosis in migrants screened before entry was 49 per 100 000 person-years (95% CI 45–53). Migrants whose chest radiographs were compatible with active tuberculosis but with negative pre-entry microbiological results were at increased risk of tuberculosis compared with those with no radiographic abnormalities (incidence rate ratio 3·2, 95% CI 2·8–3·7; p<0·0001). Incidence of tuberculosis after migration increased significantly with increasing WHO-estimated prevalence of tuberculosis in migrants' countries of origin. 35 of 318 983 pre-entry screened migrants included in a secondary analysis with typing data were assumed index cases. Estimates of the rate of assumed reactivation tuberculosis ranged from 46 (95% CI 42–52) to 91 (82–102) per 100 000 population.

Interpretation: Migrants from countries with a high incidence of tuberculosis screened before being granted entry to low-incidence countries pose a negligible risk of onward transmission but are at increased risk of tuberculosis, which could potentially be prevented through identification and treatment of latent infection in close collaboration with a pre-entry screening programme.

Funding: Wellcome Trust, UK National Institute for Health Research, UK Medical Research Council, Public Health England, and Department of Health Policy Research Programme.

No MeSH data available.


Related in: MedlinePlus