Tuberculosis incidence among migrants according to migrant status: a cohort study, Denmark, 1993 to 2015

The impact of living conditions and health interventions on tuberculosis, Denmark, 1876 to 2022

BackgroundDenmark possesses an exceptional historical data collection on tuberculosis (TB) from 1876 to the present, providing a unique opportunity to assess TB epidemiology over 147 years in Denmark.AimOur aim was to describe the TB disease burden in Denmark in relation to historical events, living conditions and health interventions during the past 147 years.MethodsWe performed a nationwide register-based ecological study including all persons with TB in Denmark from 1876 through 2022, correlating the TB incidence to social, economic and health indicators.ResultsIn Denmark, the overall TB incidence and mortality declined markedly over the past 147 years, only marginally influenced by specific TB interventions such as sanatoria, Bacillus Calmette-Guèrin (BCG) vaccination, mass screenings and antibiotics. Parallel to this decline, the country experienced improved living conditions, as illustrated by decreased infant mortality and increased life expectancy and wealth. In 1978, Denmark became a low-incidence country for TB with risk groups predominantly affected, and with a continuous change in demographics towards fewer Danish-born cases and relatively more migrant cases.ConclusionsThe decline over time in TB incidence and mortality in Denmark preceded specific TB interventions and can, first of all, be attributed to improved living conditions. TB has now become a rare disease in Denmark, predominantly occurring in particular risk groups. Future elimination of TB will require a combination of specific health interventions in these risk groups combined with a continued focus on improving socioeconomic status and living conditions.

Active screening for tuberculosis among high-risk populations in high-burden areas in Zhejiang province, China

OBJECTIVES

Tuberculosis (TB) is a major global public health concern. Although the incidence of TB in China is declining, the country continues to face many challenges regarding TB control. This study aimed to develop an active case finding (ACF) strategy for high-risk populations in areas with high TB burden and evaluate the effectiveness of the ACF strategy for early TB detection in patients to reduce TB transmission.

STUDY DESIGN

This was a descriptive study.

METHODS

From May to October 2019, active TB screening was conducted in Zhejiang Province, China. Overall, 24 high-burden townships were chosen as study sites. Residents aged ≥65 years, suffering from diabetes, diagnosed with HIV/AIDS, or with a history of TB were mobilized for screening. Chest radiography was performed for all participants in the community. Sputum specimens were collected for sputum smear tests and cultures at county-level TB-designed hospitals. A professional medical team performed the final diagnoses.

RESULTS

Overall, 130,643 residents were included, accounting for 8.85% of the total population in the selected areas. After screening, 89 confirmed cases and 419 suspected cases were identified. The detection rates for suspected and confirmed cases were 320.72/100,000 and 68.12/100,000, respectively. Individuals with a history of TB accounted for a large proportion of detected cases, and the detection rate was higher among males than in females. This study identified 10.5% of reported cases in the selected areas in 2019. In Zhejiang province, compared with the previous year, the rates of TB notification in 2019 and 2020 declined by 7.0% and 7.4%, respectively, compared with the previous year. However, the TB notification rate in 2019 was almost the same as that in 2018 (a decline of 2.5%) but sharply declined in 2020 (14.4%) in the screened areas.

CONCLUSIONS

Our findings suggest that the ACF strategy may have helped to maintain the downward trends in TB notification rates by detecting patients with TB and suspected cases in the short term.

The incidence of tuberculous pleurisy in mainland China from 2005 to 2018

Background

Currently, tuberculous pleurisy (TP) remains a serious problem affecting global public health, including in China. Our purpose was to comprehensively understand and identify the incidence of TP in mainland China between 2005 and 2018.

Methods

The data on registered TP cases from 2005 to 2018 were acquired from the National Tuberculosis Information Management System. We analyzed the demographics, epidemiology, and time-space distribution of TP patients. Then, the effects of potentially influential factors on TP incidences, such as medical expenses per capita, GDP per capita, and population density, were assessed using the Spearman correlation coefficient.

Results

The incidence of TP increased in mainland China from 2005 to 2018, with a mean incidence of 2.5 per 100,000 population. Interestingly, spring was the peak season for TP, with more notified cases. Tibet, Beijing, Xinjiang, and Inner Mongolia had the highest mean annual incidence. A moderate positive relationship was found between TP incidence, medical expenses per capita, and GDP per capita.

Conclusions

The notified incidence of TP had an elevated trend from 2005 to 2018 in mainland China. The findings of this study provide insight into the knowledge of TP epidemiology in the country, which can help optimize resource allocation to reduce the TP burden.

Tuberculosis screening among newly arrived asylum seekers in Denmark

BACKGROUND

Tuberculosis (TB) screening programmes among asylum seekers tend to focus on chest radiography (CXR) for early diagnosis, whereas knowledge on sputum examination is limited. We evaluated active TB screening using CXR and sputum culture among asylum seekers arriving in Denmark. In addition, we assessed the coverage of a voluntary health assessment.

METHODS

Between 1 February 2017 and 31 March 2019, all newly arrived asylum seekers in Denmark ≥ 18 years from TB high-incidence countries or risk groups, who attended a voluntary general health assessment, were offered active TB screening with CXR and spot sputum examination. Sputum samples were examined by culture and smear microscopy.

RESULTS

Coverage of the general health assessment was 65.1%. Among 1,154 referred for active TB screening, 923 (80.0%) attended. Of these, 854 were screened by CXR and one case of active TB was identified equivalent to a yield of 0.12%. Sputum samples were collected from 758 and one M. tuberculosis culture-positive TB case (also identified by CXR) was identified, equivalent to a yield of 0.13%. No cases were found by sputum culture screening only. In addition, screening found three cases of malignant disease.

CONCLUSION

We suggest that TB screening should focus on asylum seekers from TB high-incidence countries. Furthermore, early health assessments should be of high priority to ensure migrant health.

Social determinants of tuberculosis: a nationwide case-control study, Denmark, 1990-2018

BACKGROUND

The global vision is a world free of tuberculosis (TB). Even in resource-rich TB low-incidence settings, we need more focus on the role of social risk factors to end the TB epidemic.

METHODS

Nationwide, retrospective register-based, case-control study from 1990 to 2018, including all TB patients in Denmark ≥18 years old (n = 9581) matched 1:3 on sex and age with population controls. TB risk factors were assessed in logistic regression models and estimated by odds ratio (OR).

RESULTS

All TB patients had considerably lower socio-economic status compared with controls (P < 0.0001). Among ethnic Danes, TB was mostly found among males, persons between 35 and 65 years, those living alone, those with low educational level, persons on social welfare benefits and those with low income. Conversely, for migrants, being younger, sex and living alone were less important, whereas having children was protective. In an adjusted multivariable regression model among Danes, key risk factors for TB were being on disability pension (OR = 2.7) and cash benefits (OR = 4.7). For migrants, fewer social risk factors increased TB risk, although low income and cash benefits did (OR = 3.1).

CONCLUSION

Even today in a resourceful setting, socio-economic status drives disparities in health. In our study, multifactorial social deprivation was highly associated with TB. Especially household structure, education, employment and income were important risk factors that should be addressed in the future to accelerate TB control and end the TB epidemic.

Pregnancy and post-partum tuberculosis; a nationwide register-based case-control study, Denmark, 1990 to 2018

Background

Pregnancy increases the risk of tuberculosis (TB), however, data on TB epidemiology in pregnant women are limited.

Aim

To guide possible interventions, we analysed risk factors for TB in pregnant and post-partum women.

Methods

We conducted a nationwide retrospective register-based case–control study from January 1990 to December 2018 in Denmark. Cases were women diagnosed with TB during their pregnancy or in the post-partum period. We selected two control groups: pregnant or post-partum women without TB, and non-pregnant women with TB. Differences were assessed by chi-squared or Fisher’s exact test. Risk factors for TB were identified through logistic regression and estimated by odds ratio (OR).

Results

We identified 392 cases, including 286 pregnant and 106 post-partum women. Most were migrants (n = 366; 93%) with a shorter median time spent in Denmark (2.74 years; interquartile range (IQR): 1.52–4.64) than non-pregnant TB controls (3.98 years; IQR: 1.43–8.51). Cases less likely had a Charlson comorbidity index ≥ 2compared with non-pregnant TB controls (p < 0.0001), and had no increased risk of severe disease (p = 0.847). Migrants from other World Health Organization regions than Europe, especially Africa (OR: 187; 95%CI: 125–281) had persistently higher odds of TB.

Conclusions

In Denmark, the risk of TB in pregnant and post-partum women is increased in migrant women who have stayed in the country a median time of approximately 3 years. We recommend increased focus on TB risk during pregnancy and suggest evaluating targeted TB screening of selected at-risk pregnant women to promote early case finding and prevent TB among mothers and their newborn children.

Subclinical tuberculosis in children: diagnostic strategies for identification reported in a 6-year national prospective surveillance study

BACKGROUND

Subclinical tuberculosis (TB) is well recognized and defined as a disease state with absent or non-recognized symptoms. The study identifies factors associated with subclinical TB and diagnostic strategies in a low-burden, high-resource country.

METHODS

Data was collected between December 2013 to November 2019 through the Swiss Pediatric Surveillance Unit (SPSU). Children with culture/molecular confirmed TB, or who were treated with ≥3 anti-mycobacterial drugs, were included.

RESULTS

A total of 138 (80%) children with TB disease were included in the final analysis, of which 43 (31%) were subclinical. The median age of children with subclinical compared to symptomatic TB was 3.7(IQR 2.2 to 7) and 9.7(IQR 2.7 to 14.3) years, respectively (p=0.003). The cause of investigation for TB was recorded in 31/43 (72.1%) of children with subclinical TB, and included contact exposure in 25 (80.6%). In children with subclinical TB, diagnosis was made by a combination of the following abnormal/confirming results: culture/molecular + immunodiagnostic + chest radiography in 12 (27.9%), immunodiagnostic + chest radiography in 19 (44.2%), culture/molecular + chest radiography in 2 (4.7%), culture + immunodiagnostic in 1 (2.3%), chest radiography only in 8 (18.6%) and immunodiagnostic only in 1 (2.3%) case.

CONCLUSION

A notable proportion of children with TB had subclinical disease. This highlights the importance of non-symptom-based TB case finding in exposed children and refugees from high-TB-prevalence settings. TB screening in these asymptomatic children should therefore include a combination of immunodiagnostic testing and imaging followed by culture and molecular testing.

Initiation and completion of treatment for latent tuberculosis infection in migrants globally: a systematic review and meta-analysis

Background

Latent tuberculosis infection (LTBI) is one of the most prevalent infections globally and can lead to the development of active tuberculosis disease. In many low-burden countries, LTBI is concentrated within migrant populations often because of a higher disease burden in the migrant's country of origin. National programmes consequently focus on screening and treating LTBI in migrants to prevent future tuberculosis cases; however, how effective these programmes are is unclear. We aimed to assess LTBI treatment initiation and outcomes among migrants, and the factors that influence both.

Methods

For this systematic review and meta-analysis, we searched Embase, MEDLINE, and Global Health, and manually searched grey literature from Jan 1, 2000, to April 21, 2020. We included primary research articles reporting on LTBI treatment initiation or completion, or both, in migrants and excluded articles in which data were not stratified by migrant status, or in which the data were related to outcomes before 2000. There were no geographical or language restrictions. All included studies were quality appraised using recognised tools depending on their design, and we assessed the heterogeneity of analyses using I². We extracted data on the numbers of migrants initiating and completing treatment. Our primary outcomes were LTBI treatment initiation and completion in migrants (defined as foreign-born). We used random-effects meta-regression to examine the influence of factors related to these outcomes. The study is registered with PROSPERO (CRD42019140338).

Findings

2199 publications were retrieved screened, after which 39 publications from 13 mostly high-income, low-burden countries were included in our analyses, with treatment initiation and completion data reported for 31 598 migrants positive for LTBI, with not all articles reporting the full pathway from initiation to completion. The pooled estimate for the true proportion of migrants testing positive who initiated treatment was 69% (95% CI 51–84; I²= 99·62%; 4409 of 8764). The pooled estimate for the true proportion of migrants on treatment in datasets, who subsequently completed it was 74% (95% CI = 66–81; I²= 99·19%; 15 516 of 25 629). Where data were provided for the entire treatment pathway, the pooled estimate for the true proportion of migrants who initiated and completed treatment after a positive test was only 52% (95% CI 40–64; I²= 98·90%; 3289 of 6652). Meta-regression showed that LTBI programmes are improving, with more recent reported data (2010–20) associated with better rates of treatment initiation and completion, with multiple complex factors affecting treatment outcomes in migrants.

Interpretation

Although our analysis highlights that LTBI treatment initiation and completion in migrants has improved considerably from 2010–20, there is still room for improvement, with drop out reported along the entire treatment pathway. The delivery of these screening and treatment programmes will require further strengthening if the targets to eradicate tuberculosis in low-incidence countries are to be met, with greater focus needed on engaging migrants more effectively in the clinic and understanding the diverse and unique barriers and facilitators to migrants initiating and completing treatment.

Funding

European Society of Clinical Microbiology and Infectious Diseases, the Rosetrees Trust, the National Institute for Health Research, and the Academy of Medical Sciences.

Tuberculosis in Migrants is Among the Challenges of Tuberculosis Control in High-Income Countries

The incidence of tuberculosis (TB) is high among migrants in high-income countries. The migration process could contribute to the high incidence of TB among them. Achieving TB elimination from these settings will be difficult unless countries address the burden of TB among migrants. The aim of this review was to describe the challenges of international migration on TB control in high-income, low TB incidence countries. Among migrants, there is a high prevalence of risk factors for TB, such as exposure to TB, HIV, malnutrition, substance use, delayed diagnosis, low education, poor health-seeking, the culture, stigma and marginalization. Discriminatory policies of TB care and social barriers such as language, cultural issues and unfriendly health services may also contribute to the high prevalence of TB among them. TB control among migrants in these settings is important as migrants are vulnerable to TB infection and disease, and implementing TB care among them is difficult; it is important to reduce the TB burden in migrants and the community at large and the high risk of multidrug-resistant TB (MDR-TB). TB elimination from high-income countries requires acquiring data and analyzing it to measure the burden, having migrant-sensitive health systems, having policy and legal frameworks and multi-country partnerships and conducting research.

Spatial clustering and temporal trend analysis of international migrants diagnosed with tuberculosis in Brazil

Background

Tuberculosis (TB) in migrants is of concern to health authorities worldwide and is even more critical in Brazil, considering the country´s size and long land borders. The aim of the study was to identify critical areas in Brazil for migrants diagnosed with TB and to describe the temporal trend in this phenomenon in recent years.

Methods

This is an ecological study that used spatial analysis and time series analysis. As the study population, all cases of migrants diagnosed with TB from 2014 to 2019 were included, and Brazilian municipalities were considered as the unit of ecological analysis. The Getis-Ord Gi* technique was applied to identify critical areas, and based on the identified clusters, seasonal-trend decomposition based on loess (STL) and Prais-Winsten autoregression were used, respectively, to trace and classify temporal trend in the analyzed series. In addition, several municipal socioeconomic indicators were selected to verify the association between the identified clusters and social vulnerability.

Results

2,471 TB cases were reported in migrants. Gi* analysis showed that areas with spatial association with TB in immigrants coincide with critical areas for TB in the general population (coast of the Southeast and North regions). Four TB clusters were identified in immigrants in the states of Amazonas, Roraima, São Paulo, and Rio de Janeiro, with an upward trend in most of these clusters. The temporal trend in TB in immigrants was classified as increasing in Brazil (+ 60.66% per year [95% CI: 27.21–91.85]) and in the clusters in the states of Amazonas, Roraima, and Rio de Janeiro (+1.01, +2.15, and + 2.90% per year, respectively). The cluster in the state of São Paulo was the only one classified as stationary. The descriptive data on the municipalities belonging to the clusters showed evidence of the association between TB incidence and conditions of social vulnerability.

Conclusions

The study revealed the critical situation of TB among migrants in the country. Based on the findings, health authorities might focus on actions in regions identified, stablishing an intensive monitoring and following up, ensuring that these cases concluded their treatment and avoiding that they could spread the disease to the other regions or scenarios. The population of migrants are very dynamic, therefore strategies for following up them across Brazil are really urgent to manage the tuberculosis among international migrants in an efficient and proper way.

Tuberculosis among Migrant Populations in Sicily: A Field Report

Background

In the EU, tuberculosis (TB) mainly affects vulnerable people, including migrants. From 2014 to 2017, we have estimated the frequency of both tuberculosis and latent tuberculosis infection (LTBI) among the migrant population hosted in 41 reception centers in western Sicily (ITaCA network).

Materials and Methods

All migrants were consecutively recruited for the screening of TB infection with physical examination and TST in 1,020 migrants and with IGRA in the others 2,690. The screening was carried out 4–8 weeks after landing in Sicily. For all migrants with a positive screening test, chest X-ray and smear examination were performed. LTBI was defined by positivity of TST or IGRA with negative X-ray chest, clinical, and smear examination. Active TB was defined by radiological and/or clinical and/or sputum positivity in a patient with a TST or IGRA positivity.

Results

We evaluated a total of 3,710 migrants, of which 89% came from Sub-Saharan countries; 2,811 were males, 899 were females, with a median age of 22 years (IQR: 18–25). TB infection was diagnosed in 501 persons (13.5%) of which 440 (11.8%) had LTBI and 61 had active TB (1.6%): 1 had lymph node TB, 1 had intestinal TB, and 59 had pulmonary TB (38 sputum smear positive TB; no drug-resistant TB were observed).

Conclusions

TB screening is critical to early diagnosis and treatment.

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

BACKGROUND

The majority of tuberculosis (TB) cases in low-incidence countries occur in migrants. Only few studies have assessed the long-term TB risk in migrants after immigration, and datasets have not considered this across a range of diverse migrant groups. This nationwide study aimed to investigate long-term TB risk among migrants according to migrant status and region of origin.

METHODS

This cohort study included all migrants aged  ≥ 18 years who obtained residence in Denmark from 1993 to 2015, with a mean follow-up of 10.8 years [standard deviation (SD) 7.3]. Migrants were categorized based on legal status of residence and region of origin. Incidence rates (IR) and rate ratios (IRR) were estimated by Poisson regression.

RESULTS

A total of 142 314 migrants were included. Across all migrants, the TB risk was highest during year 1 of residence (IR 275/100 000 person-years; 95% CI 249-305) followed by a gradual decline, though TB risk remained high for over a decade. Compared with the Danish-born population, the IRRs after 7-8 years were particularly higher among former asylum seekers (IRR 31; 95% CI 20-46), quota refugees (IRR 31; 95% CI 16-71), and family-reunified with refugees (IRR 22; 95% CI 12-44). Sub-Saharan African migrants also experienced elevated risk (IRR 75; 95% CI 51-109). The proportion of migrants with pulmonary TB was 52.4%.

CONCLUSION

All migrant groups experienced an initial high TB risk, but long-term risk remained high in key migrant groups. Most European countries focus TB screening on or soon after arrival. Our study suggests that approaches to TB screening should be adapted, with migrant populations benefiting from long-term access to preventive health services.

The effect of migration on the incidence and mortality of bloodstream infection: a Danish register-based cohort study

OBJECTIVES

To investigate bloodstream infection (BSI) related to migrant status by comparing the incidence and mortality in migrants with that in non-migrants.

METHODS

In this register-based cohort study we linked a cohort of migrants and non-migrants with a bacteraemia database covering two regions in Denmark. We included first-time BSI between January 2000 and December 2015 in individuals ≥18 years. Migrants were categorized according to status: refugees or family-reunified migrants. Incidence rate ratio and mortality rate ratio were analysed using Poisson regression.

RESULTS

We identified 493 080 non-migrants, of which 3405 had BSI, and 80 740 migrants with 576 cases; of the latter, 40 222 were family-reunified migrants with 226 cases and 40 518 were refugees with 350 cases. Refugees had a higher risk of BSI than non-migrants (adjusted IRR 1.19, 95%CI 1.01-1.40). Family-reunified migrants and refugees had a higher risk of Gram-negative BSIs (adjusted IRR 1.23, 95%CI 1.00-1.51 and 1.57, 95%CI 1.32-1.86), respectively, and a lower risk of Gram-positive BSIs (adjusted IRR 0.65, 95%CI 0.51-0.83 and 0.77, 95%CI 0.63-0.95), respectively, compared to non-migrants. Originating from Southeast Asia and the Pacific was associated with an increased risk of BSI compared to non-migrants (adjusted IRR 1.26, 95%CI 1.07-1.49). We found no differences in the adjusted 30-day or 90-day mortality according to migrant status.

CONCLUSIONS

Vulnerability towards BSI differs according to migrant status. Refugees had a higher risk of BSI overall. Both refugees and family-reunified migrants had a higher incidence of Gram-negative BSI than non-migrants. Similarly, migrants from Southeast Asia and the Pacific had a higher risk of BSI than non-migrants.

Extrapulmonary tuberculosis among migrants in Europe, 1995 to 2017

Objectives

The proportion of tuberculosis (TB) cases occurring in migrants in Europe is increasing. Extrapulmonary TB poses challenges in diagnosis and treatment and causes serious morbidity and mortality, yet its extent in migrant populations is unclear. We assessed patterns of extrapulmonary TB in migrants across the European Union (EU)/European Free Trade Association (EFTA). We investigated the proportion of extrapulmonary TB cases among migrants versus non-migrants, and variations by specific site of disease, reporting European region, and migrant region of origin.

Methods

We carried out a cross-sectional secondary database analysis, utilizing 23 years of data collected between 1995 and 2017 from the European Surveillance System of the European Centre for Disease Prevention and Control for 32 EU/EFTA countries.

Results

In total, 1 270 896 TB cases were included, comprising 326 987 migrants (25.7%) and 943 909 non-migrants (74.3%). Of TB cases among migrants, 45.2% (n = 147 814) were extrapulmonary compared to 21.7% (n = 204 613) among non-migrants (p < 0.001). Lymphatic, bone/joint and peritoneal/digestive TB were more common among migrant than non-migrant extrapulmonary cases. A lower proportion of extrapulmonary TB was seen in Eastern Europe (17.4%, n = 98 656 of 566 170) and Southern Europe (29.6%, n = 62 481 of 210 828) compared with Western (35.7%, n = 89 498 of 250 517) and Northern Europe (41.8%, n = 101 792 of 243 381). Migrants from South-East Asia and Sub-Saharan Africa were at highest risk of extrapulmonary disease, with 62.0% (n = 55 401 of 89 353) and 54.5% (n = 38 327 of 70 378) of cases, respectively, being extrapulmonary.

Conclusions

Among TB cases in the EU/EFTA, extrapulmonary disease is significantly more common in migrants than in non-migrants. There is a need to improve clinical awareness of extrapulmonary TB and to integrate its detection into screening programmes.