Impact of immigration on the molecular epidemiology of Mycobacterium tuberculosis in a low-incidence country

Latent tuberculosis infection prevalence in second generation immigrants from high to low TB burden countries

BACKGROUND

Latent tuberculosis infection (LTBI) diagnosis in a country with a low tuberculosis burden is complicated. Since the prevalence of LTBI in second generation immigrants has not been well recognized, we conducted a cross-sectional study which aimed to explore the differences in LTBI prevalence between offspring of immigrants from high tuberculosis (TB) burden countries and those whose parents were born in countries with a low TB burden.

METHODS

Between May 2014 and April 2018 young native Israelis who were required to perform pre-occupational tuberculin skin tests (TST) (medical and paramedical personnel or teaching assistants of immigrants from high TB burden countries) and who had a TST result of 10mm and above were tested for QuantiFERON-TB In Tube (QFT-GIT). Statistical comparisons were made between second generation immigrants and those with both parents from a low TB burden country.

RESULTS

Of 102 patients, 71 were born to parents both of whom were from low-risk countries, 14 to one parent from a high-risk country and 17 to parents both of whom were from a high-risk country. The odds ratio for LTBI was 4.5 (95% CI, 1.2...17.2; p=0.03) if both parents were born in a high-risk country compared to both parents being from a low-risk country and 4.01 (95% CI, 1.12...14.3; p=0.03) higher compared to persons for whom at least one parent was born in a low-risk country.

CONCLUSION

The risk for latent TB is significantly higher in second generation immigrants if both parents were born in a high-risk country. IGRA should be considered before treatment to patients with a positive TST if at least one parent was born in a low-risk country in order to confirm LTBI.

Infectious disease screening outcomes and reducing barriers to care for unaccompanied asylum-seeking children: a single-centre retrospective clinical analysis

OBJECTIVE

Evaluate the Unity Clinic's infectious disease screening programme for unaccompanied asylum-seeking children (UASC), calculate rates of infection and identify further health needs.

DESIGN

Retrospective audit of electronic patient data.

SETTING AND PATIENTS

UASC who attended the Unity Clinic between 1 November 2019 and 22 March 2022.

MAIN OUTCOME MEASURES

Baseline demographics, social, mental health and journey details, infection screening and investigation results.

RESULTS

155 UASC were reviewed: 89% (138 of 155) male, median age 17 years (IQR 16-17). Most frequent countries of origin were Sudan, Eritrea and Afghanistan. Median duration of travel to the UK (n=79) was 2 years (IQR 0.5-4); 35.6% (47 of 132) arrived by boat and 54.5% (72 of 132) by road. 44.8% (69 of 154) had one or more positive infection screening results: 22.7% (35 of 154) and 1.3% (2 of 154) positive for latent and active tuberculosis, respectively; 4.6% (7 of 152) chronic active hepatitis B and 17.1% (26 of 152) for past infection; 1.3% (2 of 154) for HIV; 13.0% (19 of 146) for Strongyloides. There were three cases of syphilis (n=152; 2.0%) and one chlamydia (n=148; 0.7%)-none of whom disclosed prior sexual activity during screening. 39.6% (61 of 154) and 27.9% (43/154) reported disturbances to mood or sleep, respectively. 55.2% (85 of 154) disclosed traumatic incidents during and/or prior to their journey, including physical and sexual assault.

CONCLUSIONS

The Unity Clinic provides a thorough infectious disease screening service for UASC following national guidance. Results highlight the need for universal, non-judgemental screening for sexually transmitted infections, as targeted screening would not identify positive cases. High rates of well-being issues and previous abuse emphasise the need for multidisciplinary, collaborative approaches to care.

Dynamics of Mycobacterium tuberculosis Lineages in Oman, 2009 to 2018

Study aim. Effective Tuberculosis (TB) control measures in Oman have reduced the annual incidence of tuberculosis cases by 92% between 1981 and 2016. However, the current incidence remains above the program control target of <1 TB case per 100,000 population. This has been partly attributed to a high influx of migrants from countries with high TB burdens. The present study aimed to elucidate Mycobacterium tuberculosis infection dynamics among nationals and foreigners over a period of 10 years. Methods. The study examined TB cases reported between 2009 and 2018 and examined the spatial heterogeneity of TB cases and the distribution of M. tuberculosis genotypes defined by spoligotypes and MIRU-VNTR among Omanis and foreigners. Results. A total of 484 spoligoprofiles were detected among the examined isolates (n = 1295). These include 943 (72.8%) clustered and 352 (27.2%) unique isolates. Diverse M. tuberculosis lineages exist in all provinces in Oman, with most lineages shared between Omanis and foreigners. The most frequent spoligotypes were found to belong to EAI (318, 30.9%), CAS (310, 30.1%), T (154, 14.9%), and Beijing (88, 8.5%) lineages. However, the frequencies of these lineages differed between Omanis and foreigners. Of the clustered strains, 192 MTB isolates were further analysed via MIRU-VNTR. Each isolate exhibited a unique MIRU-VNTR profile, indicative of absence of ongoing transmission. Conclusions. TB incidence exhibits spatial heterogeneity across Oman, with high levels of diversity of M. tuberculosis lineages among Omanis and foreigners and sub-lineages shared between the two groups. However, MIRU-VNTR analysis ruled out ongoing transmission.

Effects of migration on tuberculosis epidemiological indicators in low and medium tuberculosis incidence countries: A systematic review

BACKGROUND

Tuberculosis (TB) remains one of the top ten causes of death each year globally. While the risk of migrant TB is linked to the TB incidence in their country of origin, the migration process can increase the TB risk.

OBJECTIVE

We aimed to synthesis the evidence on key differences in the epidemiological profile of TB between migrants from high TB incidence birth countries and non-migrants resident in low to medium incidence TB countries.

METHODS

We conducted a systematic review where the population was all active TB cases in countries with low to medium TB incidence (<40/100,000 population), the exposure was migration to a low or medium TB incidence country and the comparator was non-migrant TB cases in low or medium incidence countries. Overall proportions were compared between migrants and non-migrants, using Fisher's exact test. Meta-analysis of proportions was carried out for the primary outcome (active TB) while meta-analyses of odds ratios (ORs) were performed using a random effects model for secondary outcomes; sputum-smear positivity, any first line drug resistance, multi-drug resistance (MDR), clustered cases, HIV coinfections and successful treatment. Heterogeneity was evaluated and sources were investigated using subgroup and sensitivity analysis.

RESULTS

Significant differences were found in the overall proportions of high TB incidence migrants and non-migrants for MDR cases, clustered cases, HIV coinfections and successful treatment, as well as a significant difference in the OR among MDR cases (3.91).

CONCLUSION

This review has demonstrated significant differences in key epidemiological indicators between high TB incidence migrants and non-migrants, indicating policy implications.

Transmission of tuberculosis between foreign-born and Finnish-born populations in Finland, 2014-2017

We describe the epidemiology of tuberculosis (TB) and characterized Mycobacterium tuberculosis (M. tuberculosis) isolates to evaluate transmission between foreign-born and Finnish-born populations. Data on TB cases were obtained from the National Infectious Disease Register and denominator data on legal residents and their country of birth from the Population Information System. M. tuberculosis isolates were genotyped by spoligotyping and Mycobacterial Interspersed Repetitive Unit Variable Number Tandem Repeat (MIRU-VNTR). We characterized clusters by age, sex, origin and region of living which included both foreign-born cases and those born in Finland. During 2014-2017, 1015 TB cases were notified; 814 were confirmed by culture. The proportion of foreign-born cases increased from 33.3% to 39.0%. Foreign-born TB cases were younger (median age, 28 vs. 75 years), and had extrapulmonary TB or multidrug-TB more often than Finnish-born cases (P<0.01 for all comparisons). Foreign-born cases were born in 60 different countries; most commonly in Somalia (25.5%). Altogether 795 isolates were genotyped; 31.2% belonged to 80 different clusters (range, 2-13 cases/cluster). Fourteen (17.5%) clusters included isolates from both Finnish-born and foreign-born cases. An epidemiological link between cases was identified by (epidemiological) background information in two clusters. Although the proportion of foreign-born TB cases was considerable, our data suggests that transmission of TB between foreign and Finnish born population is uncommon.

Tuberculosis in migrants to Australia: Outcomes of a national screening program

Background: Few low-incidence countries are on track to achieve the ambitious target of reaching TB pre-elimination by 2035. Australia is a high-income country with a low burden of TB, which is particularly concentrated in migrant populations. As part of Australia's migration program, permanent, provisional and humanitarian visa applicants are screened for TB, along with some applicants for temporary visas.

Methods: We calculated the prevalence of all forms of active TB and bacteriologically-confirmed TB among onshore and offshore applicants for visas to Australia from July 2014 to June 2017, and investigated associated risk factors using logistic regression.

Findings: Visa applicants were predominantly young adults from various Asian countries. Among 2,381,217 applicants, 1263 cases of active TB were diagnosed, including 852 cases of bacteriologically-confirmed TB. Overall TB prevalence was 53.0 per 100,000, corresponding to one TB diagnosis for every 1887 applicants screened. TB rates increased with age and were higher among humanitarian applicants and those previously treated for TB, although most cases occurred in applicants without these risk factors. TB prevalence by country of origin was similar to WHO estimates for some countries, but considerably lower for others. For several highly represented countries of origin, rates appear to have fallen relative to earlier comparable studies.

Interpretation: Prevalence of TB among visa applicants to Australia and the consequent risk to the Australian community appear to be declining and remain low. In this context, support for TB control programs overseas and preventive interventions are likely to have the greatest impact on domestic TB burden.

Funding: No specific funding was received for this study. JMT is a recipient of an Early Career Fellowship from the Australian National Health and Medical Research Council (APP1142638).

The impact of HIV infection on tuberculosis transmission in a country with low tuberculosis incidence: a national retrospective study using molecular epidemiology

BACKGROUND

HIV is known to increase the likelihood of reactivation of latent tuberculosis to active TB disease; however, its impact on tuberculosis infectiousness and consequent transmission is unclear, particularly in low-incidence settings.

METHODS

National surveillance data from England, Wales and Northern Ireland on tuberculosis cases in adults from 2010 to 2014, strain typed using 24-locus mycobacterial-interspersed-repetitive-units-variable-number-tandem-repeats was used retrospectively to identify clusters of tuberculosis cases, subdivided into 'first' and 'subsequent' cases. Firstly, we used zero-inflated Poisson regression models to examine the association between HIV status and the number of subsequent clustered cases (a surrogate for tuberculosis infectiousness) in a strain type cluster. Secondly, we used logistic regression to examine the association between HIV status and the likelihood of being a subsequent case in a cluster (a surrogate for recent acquisition of tuberculosis infection) compared to the first case or a non-clustered case (a surrogate for reactivation of latent infection).

RESULTS

We included 18,864 strain-typed cases, 2238 were the first cases of clusters and 8471 were subsequent cases. Seven hundred and fifty-nine (4%) were HIV-positive. Outcome 1: HIV-positive pulmonary tuberculosis cases who were the first in a cluster had fewer subsequent cases associated with them (mean 0.6, multivariable incidence rate ratio [IRR] 0.75 [0.65-0.86]) than those HIV-negative (mean 1.1). Extra-pulmonary tuberculosis (EPTB) cases with HIV were less likely to be the first case in a cluster compared to HIV-negative EPTB cases. EPTB cases who were the first case had a higher mean number of subsequent cases (mean 2.5, IRR (3.62 [3.12-4.19]) than those HIV-negative (mean 0.6). Outcome 2: tuberculosis cases with HIV co-infection were less likely to be a subsequent case in a cluster (odds ratio 0.82 [0.69-0.98]), compared to being the first or a non-clustered case.

CONCLUSIONS

Outcome 1: pulmonary tuberculosis-HIV patients were less infectious than those without HIV. EPTB patients with HIV who were the first case in a cluster had a higher number of subsequent cases and thus may be markers of other undetected cases, discoverable by contact investigations. Outcome 2: tuberculosis in HIV-positive individuals was more likely due to reactivation than recent infection, compared to those who were HIV-negative.

The UCL-Lancet Commission on Migration and Health: the health of a world on the move

With one billion people on the move or having moved in 2018, migration is a global reality, which has also become a political lightning rod. Although estimates indicate that the majority of global migration occurs within low-income and middle-income countries (LMICs), the most prominent dialogue focuses almost exclusively on migration from LMICs to high-income countries (HICs). Nowadays, populist discourse demonises the very same individuals who uphold economies, bolster social services, and contribute to health services in both origin and destination locations. Those in positions of political and economic power continue to restrict or publicly condemn migration to promote their own interests. Meanwhile nationalist movements assert so-called cultural sovereignty by delineating an us versus them rhetoric, creating a moral emergency.

In response to these issues, the UCL-Lancet Commission on Migration and Health was convened to articulate evidence-based approaches to inform public discourse and policy. The Commission undertook analyses and consulted widely, with diverse international evidence and expertise spanning sociology, politics, public health science, law, humanitarianism, and anthropology. The result of this work is a report that aims to be a call to action for civil society, health leaders, academics, and policy makers to maximise the benefits and reduce the costs of migration on health locally and globally. The outputs of our work relate to five overarching goals that we thread throughout the report.

First, we provide the latest evidence on migration and health outcomes. This evidence challenges common myths and highlights the diversity, dynamics, and benefits of modern migration and how it relates to population and individual health. Migrants generally contribute more to the wealth of host societies than they cost. Our Article shows that international migrants in HICs have, on average, lower mortality than the host country population. However, increased morbidity was found for some conditions and among certain subgroups of migrants, (eg, increased rates of mental illness in victims of trafficking and people fleeing conflict) and in populations left behind in the location of origin. Currently, in 2018, the full range of migrants’ health needs are difficult to assess because of poor quality data. We know very little, for example, about the health of undocumented migrants, people with disabilities, or lesbian, gay, bisexual, transsexual, or intersex (LGBTI) individuals who migrate or who are unable to move.

Second, we examine multisector determinants of health and consider the implication of the current sector-siloed approaches. The health of people who migrate depends greatly on structural and political factors that determine the impetus for migration, the conditions of their journey, and their destination. Discrimination, gender inequalities, and exclusion from health and social services repeatedly emerge as negative health influences for migrants that require cross-sector responses.

Third, we critically review key challenges to healthy migration. Population mobility provides economic, social, and cultural dividends for those who migrate and their host communities. Furthermore, the right to the highest attainable standard of health, regardless of location or migration status, is enshrined in numerous human rights instruments. However, national sovereignty concerns overshadow these benefits and legal norms. Attention to migration focuses largely on security concerns. When there is conjoining of the words health and migration, it is either focused on small subsets of society and policy, or negatively construed. International agreements, such as the UN Global Compact for Migration and the UN Global Compact on Refugees, represent an opportunity to ensure that international solidarity, unity of intent, and our shared humanity triumphs over nationalist and exclusionary policies, leading to concrete actions to protect the health of migrants.

Fourth, we examine equity in access to health and health services and offer evidence-based solutions to improve the health of migrants. Migrants should be explicitly included in universal health coverage commitments. Ultimately, the cost of failing to be health-inclusive could be more expensive to national economies, health security, and global health than the modest investments required.

Finally, we look ahead to outline how our evidence can contribute to synergistic and equitable health, social, and economic policies, and feasible strategies to inform and inspire action by migrants, policy makers, and civil society. We conclude that migration should be treated as a central feature of 21st century health and development. Commitments to the health of migrating populations should be considered across all Sustainable Development Goals (SDGs) and in the implementation of the Global Compact for Migration and Global Compact on Refugees. This Commission offers recommendations that view population mobility as an asset to global health by showing the meaning and reality of good health for all. We present four key messages that provide a focus for future action.

Improving access to multi-drug resistant tuberculosis diagnostic and health services for refugees and migrants

By the end of 2017, an estimated 68.5 million people were displaced from their homes worldwide, of whom 25.4 million were refugees. The transmission and globalization of multi-drug resistant tuberculosis during refugee migration is a now priority issue in the public health agenda. Political and scientific commitment at the highest national and international levels will be critical to intensifying action in promoting improved health services for migrants and refugees.

Genome-based transmission modelling separates imported tuberculosis from recent transmission within an immigrant population

In many countries the incidence of tuberculosis (TB) is low and is largely shaped by immigrant populations from high-burden countries. This is the case in Norway, where more than 80 % of TB cases are found among immigrants from high-incidence countries. A variable latent period, low rates of evolution and structured social networks make separating import from within-border transmission a major conundrum to TB control efforts in many low-incidence countries. Clinical Mycobacterium tuberculosis isolates belonging to an unusually large genotype cluster associated with people born in the Horn of Africa have been identified in Norway over the last two decades. We modelled transmission based on whole-genome sequence data to estimate infection times for individual patients. By contrasting these estimates with time of arrival in Norway, we estimate on a case-by-case basis whether patients were likely to have been infected before or after arrival. Independent import was responsible for the majority of cases, but we estimate that about one-quarter of the patients had contracted TB in Norway. This study illuminates the transmission dynamics within an immigrant community. Our approach is broadly applicable to many settings where TB control programmes can benefit from understanding when and where patients acquired TB.

Tuberculosis outbreak in a nursing home involving undocumented migrants and Israeli citizens

ABSTRACK

OBJECTIVES: Israel has absorbed > 60,000 migrant from the horn of Africa (MHOA) since 2006. No cross-transmission of Mycobacterium tuberculosis from MOHA to Israeli citizens has yet been reported. This study describes the results of contact investigation and laboratory work-out of a unique mixed cluster which included both MOHA and Israeli citizens.

METHODS

Description of the results of epidemiological investigation including laboratory confirmation.

RESULTS

This unique Mycobacterium tuberculosis strain included 29 patients: 26 were MOHA and three citizens who immigrated to Israel from the former Soviet Union. This is the first mixed cluster described in Israel, which has not been represented in the SITVIT international database of genotyping markers. The transmission from non-citizens to citizens occurred in a nursing institution, when MOHA infected three other contacts- two of whom were retarded residents, one of them died. The index case was screened before employment, and was permitted to return to wok although his chest X-ray demonstrated radiological findings compatible with tuberculosis. Epidemiological links were found in other 12 MOHA members of the cluster.

CONCLUSION

This report describes cross-transmission of Mycobacterium tuberculosis from non-citizens MOHA to Israeli citizens who were residents of a nursing home, which may be the first sign for an epidemiological shift. Although cross-ethnical transmission is still rare in Israel, medical settings should employ efficient infection control measures to protect both patients and staff from Mycobacterium tuberculosis.

A Predominant Variable-Number Tandem-Repeat Cluster of Mycobacterium tuberculosis Isolates among Asylum Seekers in the Netherlands and Denmark, Deciphered by Whole-Genome Sequencing

In many countries, Mycobacterium tuberculosis isolates are routinely subjected to variable-number tandem-repeat (VNTR) typing to investigate M. tuberculosis transmission. Unexpectedly, cross-border clusters were identified among African refugees in the Netherlands and Denmark, although transmission in those countries was unlikely. Whole-genome sequencing (WGS) was applied to analyze transmission in depth and to assess the precision of VNTR typing. WGS was applied to 40 M. tuberculosis isolates from refugees in the Netherlands and Denmark (most of whom were from the Horn of Africa) that shared the exact same VNTR profile. Cluster investigations were undertaken to identify in-country epidemiological links. Combining WGS results for the isolates (all members of the central Asian strain [CAS]/Delhi genotype), from both European countries, an average genetic distance of 80 single-nucleotide polymorphisms (SNPs) (maximum, 153 SNPs) was observed. The few pairs of isolates with confirmed epidemiological links, except for one pair, had a maximum distance of 12 SNPs. WGS divided this refugee cluster into several subclusters of patients from the same country of origin. Although the M. tuberculosis cases, mainly originating from African countries, shared the exact same VNTR profile, most were clearly distinguished by WGS. The average genetic distance in this specific VNTR cluster was 2 times greater than that in other VNTR clusters. Thus, identical VNTR profiles did not represent recent direct M. tuberculosis transmission for this group of patients. It appears that either these strains from Africa are extremely conserved genetically or there is ongoing transmission of this genotype among refugees on their long migration routes from Africa to Europe.

Recent TB transmission, clustering and predictors of large clusters in London, 2010-2012: results from first 3 years of universal MIRU-VNTR strain typing

Background

The incidence of TB has doubled in the last 20 years in London. A better understanding of risk groups for recent transmission is required to effectively target interventions. We investigated the molecular epidemiological characteristics of TB cases to estimate the proportion of cases due to recent transmission, and identify predictors for belonging to a cluster.

Methods

The study population included all culture-positive TB cases in London residents, notified between January 2010 and December 2012, strain typed using 24-loci multiple interspersed repetitive units-variable number tandem repeats. Multivariable logistic regression analysis was performed to assess the risk factors for clustering using sociodemographic and clinical characteristics of cases and for cluster size based on the characteristics of the first two cases.

Results

There were 10 147 cases of which 5728 (57%) were culture confirmed and 4790 isolates (84%) were typed. 2194 (46%) were clustered in 570 clusters, and the estimated proportion attributable to recent transmission was 34%. Clustered cases were more likely to be UK born, have pulmonary TB, a previous diagnosis, a history of substance abuse or alcohol abuse and imprisonment, be of white, Indian, black-African or Caribbean ethnicity. The time between notification of the first two cases was more likely to be <90 days in large clusters.

Conclusions

Up to a third of TB cases in London may be due to recent transmission. Resources should be directed to the timely investigation of clusters involving cases with risk factors, particularly those with a short period between the first two cases, to interrupt onward transmission of TB.

Yield of active screening for tuberculosis among asylum seekers in Germany: a systematic review and meta-analysis

All asylum seekers in Germany undergo upon-entry screening for tuberculosis TB, but comprehensive evidence on the yield is lacking. We compared the national estimates with the international literature in a systematic review and meta-analysis of studies reporting the yield of TB, defined as the fraction of active TB cases detected among asylum seekers screened in Germany upon entry. We searched 11 national and international databases for empirical studies and the internet for grey literature published in English or German without restrictions on publication time. Among 1,253 screened articles, we identified six articles reporting the yield of active TB based on German data, ranging from 0.72 (95% confidence interval (CI): 0.45-1.10) to 6.41 (95% CI: 4.19-9.37) per 1,000 asylum seekers. The pooled estimate across all studies was 3.47 (95% CI: 1.78-5.73; I2 = 94.9%; p < 0.0001) per 1,000 asylum seekers. This estimate was in line with international evidence (I2 = 0%; p for heterogeneity 0.55). The meta-analysis of available international estimates resulted in a pooled yield of 3.04 (95% CI: 2.24-3.96) per 1,000. This study provides an estimate across several German federal states for the yield of TB screening in asylum seekers. Further research is needed to develop more targeted screening programmes.

Tuberculosis Outbreak in an Educational Institution in Norway

Within 1 week in April 2013, three cases of pulmonary tuberculosis (TB) were reported among students attending training sessions at an educational institution in Oslo, Norway. By the end of October 2013, a total of nine epidemiologically linked cases had been reported. The outbreak encompassed a total of 24 cases from 2009 to 2014, among which all of the 22 Mycobacterium tuberculosis isolates available had identical mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) profiles (MtbC15-9 code 10287-189) belonging to the Beijing lineage. Whole-genome sequencing (WGS) of the M. tuberculosis isolates revealed 20 variable nucleotide positions within the cluster, indicating a clonal outbreak. The most likely index case was identified and diagnosed in Norway in 2009 but was born in Asia. WGS analyses verified that all of the cases were indeed part of a single transmission chain. However, even when combining WGS and intensified contact tracing, we were unable to fully reconstruct the TB transmission events.

Crossborder travel and multidrugresistant tuberculosis (MDRTB) in Europe

The number of international migrants worldwide has continued to grow rapidly over the past fifteen years and the trend is expected to continue, making the health matters associated with migration a crucial public health challenges faced by governments and societies. Multidrug-resistant tuberculosis is a paradigm of transmissible diseases that do not respect borders and poses a multifaceted and complex challenge on migrant health. The guiding principles for the health response are the respect of equity and human rights as well as the accurate analysis of epidemiological trends and determinants of TB in migrants. The action framework "Towards tuberculosis elimination: an action framework for low-incidence countries" includes regulations for cross border migration among the top eight interventions for TB elimination in low incidence countries. Political commitment is the essential requirement, and currently, the limiting factor, to draft regulations for cross-border collaboration, establish cross-border referral systems with contact tracing and information sharing. The e-platform TB Consilium hosted by European Respiratory Society in collaboration with World Health Organization - Euro is an example of a tool that can be used to exchange information for clinical management and surveillance.

Standard Genotyping Overestimates Transmission of Mycobacterium tuberculosis among Immigrants in a Low-Incidence Country

Immigrants from regions with a high incidence of tuberculosis (TB) are a risk group for TB in low-incidence countries such as Switzerland. In a previous analysis of a nationwide collection of 520 Mycobacterium tuberculosis isolates from 2000 to 2008, we identified 35 clusters comprising 90 patients based on standard genotyping (24-locus mycobacterial interspersed repetitive-unit-variable-number tandem-repeat [MIRU-VNTR] typing and spoligotyping). Here, we used whole-genome sequencing (WGS) to revisit these transmission clusters. Genome-based transmission clusters were defined as isolate pairs separated by ≤12 single nucleotide polymorphisms (SNPs). WGS confirmed 17/35 (49%) MIRU-VNTR typing clusters; the other 18 clusters contained pairs separated by >12 SNPs. Most transmission clusters (3/4) of Swiss-born patients were confirmed by WGS, as opposed to 25% (4/16) of the clusters involving only foreign-born patients. The overall clustering proportion was 17% (90 patients; 95% confidence interval [CI], 14 to 21%) by standard genotyping but only 8% (43 patients; 95% CI, 6 to 11%) by WGS. The clustering proportion was 17% (67/401; 95% CI, 13 to 21%) by standard genotyping and 7% (26/401; 95% CI, 4 to 9%) by WGS among foreign-born patients and 19% (23/119; 95% CI, 13 to 28%) and 14% (17/119; 95% CI, 9 to 22%), respectively, among Swiss-born patients. Using weighted logistic regression, we found weak evidence of an association between birth origin and transmission (adjusted odds ratio of 2.2 and 95% CI of 0.9 to 5.5 comparing Swiss-born patients to others). In conclusion, standard genotyping overestimated recent TB transmission in Switzerland compared to WGS, particularly among immigrants from regions with a high TB incidence, where genetically closely related strains often predominate. We recommend the use of WGS to identify transmission clusters in settings with a low incidence of TB.

Tuberculosis outbreak in Eastern Norway

BACKGROUND

Tuberculosis is a rare disease in Norway, especially among those who are born here. Contact tracing for cases of pulmonary tuberculosis is essential to find others who are ill or infected, and to prevent further infection. This article describes the investigation of an outbreak in which many of those infected or ill were Norwegian adolescents.

MATERIAL AND METHOD

Nine persons directly or indirectly associated with the same educational institution were diagnosed with tuberculosis in 2013. Genetic testing of tuberculosis bacteria linked a further 13 cases of the disease reported in Eastern Norway during the period 2009-2013 to the outbreak. Information from the Norwegian Surveillance System for Communicable Diseases (MSIS) was used to investigate the outbreak, and information was also retrieved on exposure and contact networks.

RESULTS

The first patient at the educational institution had long-term symptoms before diagnosis. Contact tracing for this case included 319 persons, of whom eight were ill, 49 infected and 37 received preventive therapy. The extent of contract tracing for the remaining 21 cases varied and included a total of 313 persons, of whom two were found to be ill (included in the 21 cases), 30 were infected and 12 received preventive therapy.

INTERPRETATION

Delayed diagnosis led to an unusually large tuberculosis outbreak in a Norwegian context. The extent of contact tracing varied with no obvious relation to the infectiousness of the index patient. The outbreak demonstrates the importance of continued vigilance with regard to tuberculosis as a differential diagnosis, also among patients born in Norway.

Tuberculosis in immigrants in Finland, 1995-2013

Increasing immigration from high tuberculosis (TB) incidence countries is a challenge for surveillance and control in Finland. Here, we describe the epidemiology of TB in immigrants by using national surveillance data. During 1995-2013, 7030 (84·7%) native and 1199 (14·4%) immigrant cases were identified. The proportion of immigrant cases increased from 5·8% in 1995 to 32·1% in 2013, consistent with increasing immigrant population (2·1-5·6%) and decreasing incidence of TB in the native population (from 12·1 to 3·5/100 000). TB cases in immigrants were significantly younger, more often female, and had extrapulmonary TB more often than native cases (P < 0·01 for all comparisons); multidrug resistance was also more common in immigrants than natives (P < 0·01). Immigrant cases were born in 82 different countries; most commonly in Somalia and the former Soviet Union/Russia. During 2008-2013, 433 Mycobacterium tuberculosis isolates from immigrants were submitted for spoligotyping; 10 different clades were identified. Clades were similar to those found in the case's country of birth. Screening immigrants from high-incidence countries and raising awareness of common characteristics and symptoms of TB is important to ensure early diagnosis and to prevent transmission.

Higher Rate of Tuberculosis in Second Generation Migrants Compared to Native Residents in a Metropolitan Setting in Western Europe

BACKGROUND

In Western Europe, migrants constitute an important risk group for tuberculosis, but little is known about successive generations of migrants. We aimed to characterize migration among tuberculosis cases in Berlin and to estimate annual rates of tuberculosis in two subsequent migrant generations. We hypothesized that second generation migrants born in Germany are at higher risk of tuberculosis compared to native (non-migrant) residents.

METHODS

A prospective cross-sectional study was conducted. All tuberculosis cases reported to health authorities in Berlin between 11/2010 and 10/2011 were eligible. Interviews were conducted using a structured questionnaire including demographic data, migration history of patients and their parents, and language use. Tuberculosis rates were estimated using 2011 census data.

RESULTS

Of 314 tuberculosis cases reported, 154 (49.0%) participated. Of these, 81 (52.6%) were first-, 14 (9.1%) were second generation migrants, and 59 (38.3%) were native residents. The tuberculosis rate per 100,000 individuals was 28.3 (95CI: 24.0-32.6) in first-, 10.2 (95%CI: 6.1-16.6) in second generation migrants, and 4.6 (95%CI: 3.7-5.6) in native residents. When combining information from the standard notification variables country of birth and citizenship, the sensitivity to detect second generation migration was 28.6%.

CONCLUSIONS

There is a higher rate of tuberculosis among second generation migrants compared to native residents in Berlin. This may be explained by presumably frequent contact and transmission within migrant populations. Second generation migration is insufficiently captured by the surveillance variables country of birth and citizenship. Surveillance systems in Western Europe should allow for quantifying the tuberculosis burden in this important risk group.

Description of the largest cluster of tuberculosis notified in Norway 1997-2011: is the Norwegian tuberculosis control programme serving its purpose for high risk groups?

Background

Approximately 90% of new tuberculosis (TB) cases notified in Norway are asylum seekers and other immigrants from high-incidence countries. Asylum seekers are screened upon arrival at the National Immigration Centre. Other immigrants receive a letter from the Municipal Health Services requesting that they present for screening in their municipality of residence. In order to identify potential areas where the TB control programme could be better adapted for these groups, we studied the largest cluster of TB cases (“cluster X”) notified in Norway until 2011.

Methods

Cases were defined as TB notifications reported to MSIS between January 1997 and December 2011 with identical IS6110 RFLP assigned to cluster X. We described the cases in cluster X by using data from the Norwegian Surveillance System for Communicable Diseases (MSIS). Missing or incomplete information in MSIS was obtained from the National Reception Centre, Oslo University Hospital and Municipal Health services.

Results

Of a total of 44 individuals meeting the case definition, 36 originated from Somalia and eight from other high-incidence countries. Twenty nine were asylum seekers and 15 were other immigrants. Upon arrival, 18/44 had been diagnosed with latent TB infection (LTBI), 9/44 tested negative for LTBI and 4/44 had been diagnosed with active TB. Results of TB-screening upon arrival were not available for the remaining 13/44 (one asylum seeker and 12 other immigrants). Five of the 12 other immigrants had still not been screened for TB after staying one year or longer in Norway.

Conclusions

Most cases in cluster X with available results of TB-screening were already infected at arrival, indicating that their disease could be due to endogenous reactivation, rather than recent transmission after arrival to Norway. TB-status upon arrival was unknown for many of the other immigrants due to lack of initial screening. The reasons why conduction of the initial screening among other immigrants is failing should be explored and methods to simplify the TB screening at arrival should be implemented.

Towards tuberculosis elimination: an action framework for low-incidence countries

This paper describes an action framework for countries with low tuberculosis (TB) incidence (<100 TB cases per million population) that are striving for TB elimination. The framework sets out priority interventions required for these countries to progress first towards "pre-elimination" (<10 cases per million) and eventually the elimination of TB as a public health problem (less than one case per million). TB epidemiology in most low-incidence countries is characterised by a low rate of transmission in the general population, occasional outbreaks, a majority of TB cases generated from progression of latent TB infection (LTBI) rather than local transmission, concentration to certain vulnerable and hard-to-reach risk groups, and challenges posed by cross-border migration. Common health system challenges are that political commitment, funding, clinical expertise and general awareness of TB diminishes as TB incidence falls. The framework presents a tailored response to these challenges, grouped into eight priority action areas: 1) ensure political commitment, funding and stewardship for planning and essential services; 2) address the most vulnerable and hard-to-reach groups; 3) address special needs of migrants and cross-border issues; 4) undertake screening for active TB and LTBI in TB contacts and selected high-risk groups, and provide appropriate treatment; 5) optimise the prevention and care of drug-resistant TB; 6) ensure continued surveillance, programme monitoring and evaluation and case-based data management; 7) invest in research and new tools; and 8) support global TB prevention, care and control. The overall approach needs to be multisectorial, focusing on equitable access to high-quality diagnosis and care, and on addressing the social determinants of TB. Because of increasing globalisation and population mobility, the response needs to have both national and global dimensions.

Tuberculosis among migrant populations in the European Union and the European Economic Area

Background: Although tuberculosis (TB) incidence has been decreasing in the European Union/European Economic Area (EU/EEA) in the last decades, specific subgroups of the population, such as migrants, remain at high risk of TB. This study is based on the report ‘Key Infectious Diseases in Migrant Populations in the EU/EEA’ commissioned by The European Centre for Disease Prevention and Control. Methods: We collected, critically appraised and summarized the available evidence on the TB burden in migrants in the EU/EEA. Data were collected through: (i) a comprehensive literature review; (ii) analysis of data from The European Surveillance System (TESSy) and (iii) evidence provided by TB experts during an infectious disease workshop in 2012. Results: In 2010, of the 73 996 TB cases notified in the EU/EEA, 25% were of foreign origin. The overall decrease of TB cases observed in recent years has not been reflected in migrant populations. Foreign-born people with TB exhibit different socioeconomic and clinical characteristics than native sufferers. Conclusion: This is one of the first studies to use multiple data sources, including the largest available European database on infectious disease notifications, to assess the burden and provide a comprehensive description and analysis of specific TB features in migrants in the EU/EEA. Strengthened information about health determinants and factors for migrants’ vulnerability is needed to plan, implement and evaluate targeted TB care and control interventions for migrants in the EU/EEA.

Diagnosis of Mycobacterium tuberculosis using molecular biology technology

OBJECTIVE

To present an integrated molecular biology dedicated system for tuberculosis diagnosis.

METHODS

One hundred and five sputum specimens from patients strongly suspected by clinical parameters of tuberculosis were studied by Ziehl-Neelsen staining, by cultivation on solid medium and by a balanced heminested fluorometric PCR system (Orange G3TB) that could preserve worker safety and produce a rather pure material free of potential inhibitors. DNA amplification was performed in a low cost tuberculosis termocycler-fluorometer. Produced double stranded DNA was flurometrically detected. The whole reaction was conducted in one single tube which would not be opened after adding the processed sample in order to minimize the risk of cross contamination with amplicons.

RESULTS

The assay was able to detect 30 bacillus per sample mL with 99.8% interassay variation coefficient. PCR was positive in 23 (21.9%) tested samples (21 of them were smear negative). In our study it showed a preliminary sensitivity of 94.5% for sputum and an overall specificity of 98.7%.

CONCLUSIONS

Total run time of the test is 4 h with 2.5 real working time. All PCR positive samples are also positive by microbiological culture and clinical criteria. Results show that it could be a very useful tool to increase detection efficiency of tuberculosis disease in low bacilus load samples. Furthermore, its low cost and friendly using make it feasible to run in poor regions.

Molecular epidemiology of tuberculosis in Sicily, Italy: what has changed after a decade?

Background

We aimed to investigate the molecular epidemiology of Mycobacterium tuberculosis complex (MTBC) isolates in the province of Palermo, Sicily, Italy, by characterizing 183 isolates identified in the years 2004-2012. A comparison with 104 MTBC strains identified in the same geographic area in the years 1994-2000 was also carried out.

Methods

One hundred eighty-three MTBC isolates identified in Palermo, Italy, in the years 2004-2012 were analyzed by spoligotyping and the 24 mycobacterial interspersed repetitive unit (MIRU)-variable-number tandem-repeat (VNTR) method typing. Susceptibility testing to streptomycin, isoniazid, rifampin and ethambutol was also performed. Furthermore, the spoligotyping dataset obtained from 104 MTBC isolates identified from 1994 to 2000 was reanalyzed. Distribution into lineages and clustering of isolates in the two periods was compared.

Results

One hundred seventy-seven out of the 183 isolates of MTBC submitted to molecular typing were fully characterized. Of these, 108 were from Italian-born and 69 from foreign-born individuals. Eleven different lineages and 35 families-subfamilies were identified with the most represented lineages being Haarlem (26.5%), T (19.2%), LAM (13.6%) and S (8.5%). Except for the Haarlem lineage, where isolates from foreign-born patients were overrepresented, the distribution of isolates in the families belonging to the Euro-American clone reflected the proportions of the two subpopulations. A total of 27 (15.2%) strains were clustered and three clusters were mixed. Approximately 25% of the 183 MTBC isolates under study proved to be resistant to at least one antiTB drug, with only three isolates categorized as multidrug resistant (MDR). When MTBC isolates identified in the years 1994-2000 were reanalyzed, lineages T (30.8%), LAM (29.8%), Haarlem (16.3%) and S (13.5%) proved to be predominant. No MTBC isolates belonging to CAM, U, CAS, Turkish and Ural lineages were identified.

Conclusions

A wide heterogeneity was detected among the MTBC strains isolated in the years 2004-2012. Six lineages were not present among the isolates of the period 1994-2000. Comparison between distribution of lineages in the two consecutive periods depicts rapid and deep changes in the TB epidemiology in Palermo, Italy. An universal and continued laboratory-based surveillance of TB in Sicily is required.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0602-4) contains supplementary material, which is available to authorized users.

Collaboration between municipal and specialist public health care in tuberculosis screening in Norway

Background

About 90% of new tuberculosis (TB) cases in Norway appear among immigrants from high incidence countries. There is a compulsory governmental tuberculosis screening programme for immigrants; immigrants with positive screening results are to be referred from municipal health care to the specialist health care for follow-up. Recent studies of the screening programme have shown inadequate follow-up. One of the main problems has been that patients referred for follow-up have not attended their appointment at the specialist health care.

TB screening in the municipality of Trondheim is done by two different teams: the Refugee Healthcare Centre (RHC) screens refugees and the Vaccination and Infection Control Office (VICO) screens all the other groups. Patients with positive findings on screening are referred to the hospital’s Pulmonary Out-patient Department (POPD). The municipal and referral level public health care initiated a project aiming to improve follow-up through closer collaboration.

Methods

An intervention group and a pre-intervention control group were established for each screening group. During meetings between staff from the municipality and the POPD, inadequacies in the screening process were identified, and changes in procedures for summoning patients, and time and place for tests were implemented. For both the intervention group and the control group, time from referral until consultation at the POPD and number of patients that attended their first appointment were registered and compared.

Results

In the VICO group, 97/134 (72%) of the controls and 109/123 (89%) of the intervention group attended their first appointment at the POPD after 30 weeks (median) and 10 weeks, respectively. In the RHC group 28/46 (61%) of the controls and 55/59 (93%) in the intervention group attended their first appointment after 15 and 8 weeks (median) respectively.

Conclusion

Increased collaboration between the municipal and specialist health care can improve the follow-up of positive TB screening results.

Neighborhood socioeconomic position and tuberculosis transmission: a retrospective cohort study

Background

Current understanding of tuberculosis (TB) genotype clustering in the US is based on individual risk factors. This study sought to identify whether area-based socioeconomic status (SES) was associated with genotypic clustering among culture-confirmed TB cases.

Methods

A retrospective cohort analysis was performed on data collected on persons with incident TB in King County, Washington, 2004–2008. Multilevel models were used to identify the relationship between area-level SES at the block group level and clustering utilizing a socioeconomic position index (SEP).

Results

Of 519 patients with a known genotyping result and block group, 212 (41%) of isolates clustered genotypically. Analyses suggested an association between lower area-based SES and increased recent TB transmission, particularly among US-born populations. Models in which community characteristics were measured at the block group level demonstrated that lower area-based SEP was positively associated with genotypic clustering after controlling for individual covariates. However, the trend in higher clustering odds with lower SEP index quartile diminished when additional block-group covariates.

Conclusions

Results stress the need for TB control interventions that take area-based measures into account, with particular focus on poor neighborhoods. Interventions based on area-based characteristics, such as improving case finding strategies, utilizing location-based screening and addressing social inequalities, could reduce recent rates of transmission.

The effect of weekly text-message communication on treatment completion among patients with latent tuberculosis infection: study protocol for a randomised controlled trial (WelTel LTBI)

INTRODUCTION

Interventions to improve adherence to treatment for latent tuberculosis infection (LTBI) are necessary to improve treatment completion rates and optimise tuberculosis (TB) control efforts. The high prevalence of cell phone use presents opportunities to develop innovative ways to engage patients in care. A randomised controlled trial (RCT), WelTel Kenya1, demonstrated that weekly text messages improved antiretroviral adherence and clinical outcomes among patients initiating HIV treatment. The aim of this study is to determine whether the WelTel intervention can improve treatment completion among patients with LTBI and to evaluate the intervention's cost-effectiveness.

METHODS AND ANALYSIS

This open, two-site, parallel RCT (WelTel LTBI) will be conducted at TB clinics in Vancouver and New Westminster, British Columbia, Canada. Over 2 years, we aim to recruit 350 individuals initiating a 9-month isoniazid regimen. Participants will be randomly allocated to an intervention or control (standard care) arm in a 1:1 ratio. Intervention arm participants will receive a weekly text-message 'check-in' to which they will be asked to respond within 48 h. A TB clinician will follow-up instances of non-response and problems that are identified. Participants will be followed until treatment completion (up to 12 months) or discontinuation. The primary outcome is self-reported treatment completion (taking ≥80% of doses within 12 months). Secondary outcomes include daily adherence (percentage of days participants used medication as prescribed) and time to treatment completion. Patient satisfaction with the intervention will be evaluated, and the intervention's cost-effectiveness will be analysed through decision-analytic modelling.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the University of British Columbia. This trial will test the efficacy and cost-effectiveness of the WelTel intervention to improve treatment completion among patients with LTBI. Trial results and economic evaluation will help inform policy and practice on the use of WelTel in this population.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT01549457.

Tuberculosis control in big cities and urban risk groups in the European Union: a consensus statement

In low-incidence countries in the European Union (EU), tuberculosis (TB) is concentrated in big cities, especially among certain urban high-risk groups including immigrants from TB high-incidence countries, homeless people, and those with a history of drug and alcohol misuse. Elimination of TB in European big cities requires control measures focused on multiple layers of the urban population. The particular complexities of major EU metropolises, for example high population density and social structure, create specific opportunities for transmission, but also enable targeted TB control interventions, not efficient in the general population, to be effective or cost effective. Lessons can be learnt from across the EU and this consensus statement on TB control in big cities and urban risk groups was prepared by a working group representing various EU big cities, brought together on the initiative of the European Centre for Disease Prevention and Control. The consensus statement describes general and specific social, educational, operational, organisational, legal and monitoring TB control interventions in EU big cities, as well as providing recommendations for big city TB control, based upon a conceptual TB transmission and control model.

Molecular epidemiology of tuberculosis in Finland, 2008-2011

In industrialized countries the majority of tuberculosis (TB) cases are linked to immigration. In Finland, most cases are still Finnish born but the number of foreign born cases is steadily increasing. In this 4-year population based study, the TB situation in Finland was characterized by a genotypic analysis of Mycobacterium tuberculosis isolates. A total of 1048 M. tuberculosis isolates (representing 99.4% of all culture positive cases) were analyzed by spoligotyping and MIRU. Spoligotype lineages belonging to the Euro-American family were predominant among the Finnish isolates, particularly T (n=346, 33.0%) and Haarlem (n=237, 22.6%) strains. The lineage signature was unknown for 130 (12.4%) isolates. Out of the 17 multi-drug resistant TB strains, 10 (58.8%) belonged to the Beijing lineage. In total, 23 new SIT designations were given and 51 orphan strains were found, of which 58 patterns were unique to Finland. Phylogeographical TB mapping as compared to neighboring countries showed that the population structure in Finland most closely resembled that observed in Sweden. By combining spoligotyping and MIRU results, 98 clusters comprising 355 isolates (33.9%) were found. Only 10 clusters contained both Finnish and foreign born cases. In conclusion, a large proportion of the M. tuberculosis isolates were from Finnish born elderly patients. Moreover, many previously unidentified spoligotype profiles and isolates belonging to unknown lineages were encountered.

Tuberculosis transmission among immigrants and autochthonous populations of the eastern province of Saudi Arabia

Background

Eastern province of Saudi Arabia is an industrial zone with large immigrant population and high level of tuberculosis case notification among immigrants. The impact of immigration and current trends of tuberculosis transmission among immigrants and autochthonous population in the region had not been investigated so far using molecular tools.

Methodology

During 2009- 2011, a total of 524 Mycobacterium tuberculosis isolates were collected from the central tuberculosis reference laboratory, representing an estimated 79.2% of the culture-positive tuberculosis cases over the study period in the province. These isolates were genotyped by using 24 locus-based MIRU-VNTR typing and spoligotyping followed by first line drug susceptibility testing. The molecular clustering profiles and phylogenetic diversity of isolates were determined and compared to the geographical origins of the patients.

Principle Findings

Genotyping showed an overall predominance of Delhi/CAS (29.4%), EAI (23.8%) and Ghana (13.3%) lineages, with slightly higher proportions of Delhi/CAS among autochthonous population (33.3 %) and EAI (30.9%) among immigrants. Rate of any drug resistance was 20.2% with 2.5% of multi-drug resistance. Strain cluster analysis indicated 42 clusters comprising 210 isolates, resulting in a calculated recent transmission index of 32.1%. Overall shared cluster ratio was 78.6% while 75.8% were shared between autochthonous population and immigrant population with a predominance of immigrants from South east Asia (40.7%). In contrast, cross national transmission within the immigrant population was limited (24.2%). Younger age (15-30- p value-0.043, 16-45, p value 0.030), Saudi nationality (p value-0.004) and South East Asian origin (p value-0.011) were identified as significant predisposing factors for molecular strain clustering.

Conclusions

The high proportion of molecular clusters shared among the autochthonous and immigrant populations suggests a high permeability of tuberculosis transmission between both populations in the province. These results prompt for the need to strengthen the current tuberculosis control strategies and surveillance programs.

Tuberculosis transmission between foreign- and native-born populations in the EU/EEA: a systematic review

Tuberculosis (TB) control programmes of many low TB incidence countries of the European Union/European Economic Area (EU/EEA) perceive challenges in controlling TB due to high numbers of TB in migrants from high-incidence countries.

To assess the extent of TB transmission from the foreign-born to the native-born population, we quantitatively investigated the dynamics of TB transmission between these populations in the EU/EEA, using published molecular epidemiological studies. We searched PubMed and EMBASE databases from 1990 to August 2012.

We identified 15 studies performed during 1992–2007 covering 12,366 cases, of which median (range) 49.2% (17.7%–86.4%) were foreign-born. The proportion of clustered isolates ranged between 8.5% and 49.1% of the total number of TB cases genotyped and among these, foreign-born cases were equally or more likely to have unique isolates compared to native-born cases. One third of the clusters were “mixed”, i.e. composed of foreign- and native-born cases, involving 0–34.2% of all genotyped cases. Cross-transmission among foreign and native populations was bidirectional, with wide differences across studies.

This systematic review provides evidence that TB in a foreign-born population does not have a significant influence on TB in the native population in EU/EEA.

TB in foreign-born cases does not have a significant influence on TB in the native population in EU/EEAhttp://ow.ly/pTTXv

Spectrum of Disease in Children Treated for Tuberculosis at a Tertiary Children's Hospital in Australia

BACKGROUND

Tuberculosis (TB) notification rates in Australia have plateaued at a low level, but the pediatric disease burden remains poorly described. Child cases provide a marker of recent transmission and present unique diagnostic challenges.

METHODS

We performed an audit of all children (<18 years of age) treated for TB at the Children's Hospital at Westmead, Sydney, Australia from January 2008 to December 2011. Demographics, clinical presentation, diagnostics, disease profile, treatment, and outcome were reviewed.

RESULTS

A total of 25 children were treated for TB: 15 had microbiologically confirmed TB; 7 were diagnosed on clinical grounds; and in 3, an alternate diagnosis was established (2 bacille Calmette-Guérin disease and 1 atypical mycobacterial infection). Of the 22 TB cases, 21 had a history of immigration or travel to a TB-endemic country and 4 reported recent contact with a TB source case within Australia. Isolated intrathoracic TB was documented in 16 (72%) cases. Symptoms on presentation included the following: lethargy, weakness, or malaise (75%); fever (73%); and cough (64%). Among the 15 children with microbiologically confirmed TB, 11 (73%) were positive by culture and 11 of 13 (85%) by polymerase chain reaction test. Tuberculin skin test was positive (≥10 mm) in 80% (16 of 20) of cases, and interferon-gamma release assay was positive in 87% (13 of 15) of cases. All children received directly observed therapy and recovered.

CONCLUSIONS

This series demonstrates the broad spectrum of disease with which pediatric TB cases present and the need for ongoing vigilance. A more comprehensive review of pediatric TB cases throughout Australia would be informative.

Rapid and biosecure diagnostic test for tuberculosis

Early and rapid detection of the causative organism is necessary in tuberculosis. We present here an integrated and dedicated molecular biology system for tuberculosis diagnosis. One hundred and eighty-nine (189) biologic specimens from patients strongly suspected by clinical parameters of tuberculosis were studied by Ziehl-Neelsen staining, cultivation on a solid medium, and by a balanced heminested fluorometric PCR system (Orange G3TB) that preserves worker safety and produces a rather pure material free of potential inhibitors. DNA amplification was carried out in a low cost using a tuberculosis thermocycler-fluorometer. The double stranded DNA produced is fluorometrically detected. The whole reaction is carried out in one single tube which is never opened after adding the processed sample, thus minimizing the risk of cross contamination with amplicons. The assay is able to detect 30 bacilli/ml of sample having a 99.8 % inter-assay coefficient of variation. PCR was positive in 36 (18.9 %) tested samples (33 of them were smear-negative). In our study, it yields a preliminary overall sensitivity of 97.4 %. In addition, its overall specificity is 98.7 %. The total run time of the test is 4 h with two and a half real working hours. All PCR-positive samples also had a positive result by microbiological culture and clinical criteria. The results obtained showed that it could be a very useful tool to increase efficiency in detecting the tuberculosis disease in low bacillus inoculum samples. Furthermore, its low cost and friendly usage make it feasible to be used in regions with poor development.

The re-emergence of tuberculosis: what have we learnt from molecular epidemiology?

Tuberculosis (TB) has re-emerged over the past two decades: in industrialized countries in association with immigration, and in Africa owing to the human immunodeficiency virus epidemic. Drug-resistant TB is a major threat worldwide. The variable and uncertain impact of TB control necessitates not only better tools (diagnostics, drugs, and vaccines), but also better insights into the natural history and epidemiology of TB. Molecular epidemiological studies over the last two decades have contributed to such insights by answering long-standing questions, such as the proportion of cases attributable to recent transmission, risk factors for recent transmission, the occurrence of multiple Mycobacterium tuberculosis infection, and the proportion of recurrent TB cases attributable to re-infection. M. tuberculosis lineages have been identified and shown to be associated with geographical origin. The Beijing genotype is strongly associated with multidrug resistance, and may have escaped from bacille Calmette-Guérin-induced immunity. DNA fingerprinting has quantified the importance of institutional transmission and laboratory cross-contamination, and has helped to focus contact investigations. Questions to be answered in the near future with whole genome sequencing include identification of chains of transmission within clusters of patients, more precise quantification of mixed infection, and transmission probabilities and rates of progression from infection to disease of various M. tuberculosis lineages, as well as possible variations in vaccine efficacy by lineage. Perhaps most importantly, dynamics in the population structure of M. tuberculosis in response to control measures in high-prevalence areas should be better understood.

Un abordaje comparativo en torno a la incidencia de la tuberculosis en inmigrantes bolivianos de Buenos Aires y São Paulo

Este trabajo expone de manera exploratoria y desde una perspectiva sociosanitaria regional, en clave comparativa, algunas dimensiones de análisis en torno a la incidencia de la tuberculosis en inmigrantes bolivianos de las ciudades de Buenos Aires y São Paulo. En ambos casos, se trata de un padecimiento ligado a sus modos de vida y de trabajo precarios en talleres textiles clandestinos. Sumado a lo anterior, la falta de documentación en regla, las dificultades de acceso a la atención sanitaria pública y el sufrimiento social experimentado, potencian la situación de vulnerabilidad social de estas personas; aumentando los riesgos de infectarse y desarrollar la enfermedad.

[Comparative epidemiological study of the tuberculosis - migrant and native subjects in Guadeloupe from 2006 to 2011]

INTRODUCTION

Most of the migrants residing in Guadeloupe are from neighboring Caribbean islands, some of which are characterized by a high incidence of tuberculosis. The objective of this retrospective and observational study was to define the epidemiological characteristics of tuberculosis affecting migrant and native populations in Guadeloupe.

METHODS

We describe all cases of tuberculosis in Guadeloupe identified in these two populations between 1 July 2006 and 30 June 2011.

RESULTS

The incidence of TB among migrants in Guadeloupe was seven times higher than that in native subjects in 2010 (33.4 vs. 5.5 new cases/100,000 inhabitants). Tuberculosis affecting the migrant population was characterized by young age of the patients (42 vs. 55 years) and a significant proportion of co-infection by the human immunodeficiency virus (HIV) (47 vs. 14%, P<0.001). Among the patient population studied, the HIV infection increased the risk of developing severe tuberculosis (adjusted odds ratio: 2.9; 95%CI: 1.2-6.8). Moreover, HIV infection was also a risk factor for death where the infection was not controlled (CD4 count <200 units per microliter; adj risk ratio: 3.9; 1.2-12.4).

CONCLUSION

This study shows that the migrant population in Guadeloupe is at increased risk of tuberculosis and should be considered as a priority target for tuberculosis control program.

Equity in health: tuberculosis in the Bolivian immigrant community of São Paulo, Brazil

OBJECTIVES

To analyse the profile of tuberculosis (TB) among Bolivian immigrants, investigate the impact that this population has on the trends of TB and assess equity in access to TB treatment, in the city of São Paulo, Brazil.

METHODS

Descriptive study of the epidemiological profile of TB in four city districts with large Bolivian populations, comparing cases among Brazilians and Bolivians, during the 1998-2008 period was carried out. We used logistic regression to adjust the treatment outcome for potential confounders.

RESULTS

We identified 2056 new TB cases: 65.7% in Brazilians, 32.1% in Bolivians and 2.2% among other nationalities. Although TB incidence remained stable (high) over the study period, the annual proportion of cases among Bolivians increased from 15.0% to 53.0%. In comparison with the Brazilians, the Bolivians were younger (median age, 24 vs. 40 years; P < 0.0001) and presented a lower unemployment rate (3.1%vs. 11.6%; P < 0.0001), a lower rate of HIV co-infection (1.5%vs. 28.5%; P< 0.001), a higher proportion of individuals receiving supervised treatment (81.5%vs. 62.0%; P < 0.0001) and a higher proportion of cures (71.6%vs. 63.2%; P< 0.0001). After having been adjusted for potential confounder, cure after treatment was not associated with nationality.

CONCLUSIONS

  Bolivian immigrants influenced the incidence but not the trends of TB among Brazilians in the study area. We found no significant differences between Bolivians and Brazilians regarding healthcare access or treatment outcome. Guaranteed universal health care access for all, including undocumented individuals, contributes to health equity. Specific intervention strategies are warranted for immigrants with tuberculosis.

Clustered tuberculosis in a low-burden country: nationwide genotyping through 15 years

Molecular genotyping of Mycobacterium tuberculosis has proved to be a powerful tool in tuberculosis surveillance, epidemiology, and control. Based on results obtained through 15 years of nationwide IS6110 restriction fragment length polymorphism (RFLP) genotyping of M. tuberculosis cases in Denmark, a country on the way toward tuberculosis elimination, we discuss M. tuberculosis transmission dynamics and point to areas for control interventions. Cases with 100% identical genotypes (RFLP patterns) were defined as clustered, and a cluster was defined as cases with an identical genotype. Of 4,601 included cases, corresponding to 76% of reported and 97% of culture-verified tuberculosis cases in the country, 56% were clustered, of which 69% were Danes. Generally, Danes were more often in large clusters (≥ 50 persons), older (mean age, 45 years), and male (male/female ratio, 2.5). Also, Danes had a higher cluster frequency within a 2-year observation window (60.8%), and higher clustering rate of new patterns over time, compared to immigrants. A dominant genotype, cluster 2, constituted 44% of all clustered and 35% of all genotyped cases. This cluster was primarily found among Danish males, 30 to 59 years of age, often socially marginalized, and with records of alcohol abuse. In Danes, cluster 2 alone was responsible for the high cluster frequency level. Immigrants had a higher incidence of clustered tuberculosis at a younger age (0 to 39 years). To achieve tuberculosis elimination in Denmark, high-risk transmission environments, like the cluster 2 environment in Danes, and specific transmission chains in immigrants in the capital area, e.g., homeless/socially marginalized Somalis/Greenlanders, often with alcohol abuse, must be targeted, including groups with a high risk of reactivation.

Migrant tuberculosis: the extent of transmission in a low burden country

Background

Human migration caused by political unrest, wars and poverty is a major topic in international health. Infectious diseases like tuberculosis follow their host, with potential impact on both the migrants and the population in the recipient countries. In this study, we evaluate Mycobacterium tuberculosis transmission between the national population and migrants in Denmark.

Methods

Register study based on IS6110-RFLP results from nationwide genotyping of tuberculosis cases during 1992 through 2004. Cases with 100% identical genotypes were defined as clustered and part of a transmission chain. Origin of clusters involving both Danes and migrants was defined as Danish/migrant/uncertain. Subsequently, the proportion of cases likely infected by the "opposite" ethnic group was estimated.

Results

4,631 cases were included, representing 99% of culture confirmed cases during 1992 through 2004. Migrants contributed 61.6% of cases. Up to 7.9% (95% CI 7.0-8.9) of migrants were infected by Danes. The corresponding figure was 5.8% (95% CI 4.8-7.0) for Danes. Thus, transmission from Danes to migrants occurred up to 2.5 (95% CI 1.8-3.5) times more frequent than vice versa (OR = 1). A dominant strain, Cluster-2, was almost exclusively found in Danes, particular younger-middle-aged males.

Conclusions

Transmission between Danes and migrants is limited, and risk of being infected by the "opposite" ethnic group is highest for migrants. TB-control efforts should focus on continues micro-epidemics, e.g. with Cluster-2 in Danes, prevention of reactivation TB in high-risk migrants, and outbreaks in socially marginalized migrants, such as Somalis and Greenlanders. Fears that TB in migrants poses a threat for resident Danes seem exaggerated and unjustified. We believe this to be true for other low incidence countries as well.

Characteristics of non-clustered tuberculosis in a low burden country

Molecular genotyping studies often focus on clustered tuberculosis and recent transmission. Less attention has been paid to non-clustered tuberculosis. However, non-clustered cases also contribute significantly to the tuberculosis burden, especially in low-incidence countries. The objective of this study is to characterize non-clustered tuberculosis cases in Denmark and point out potential implications for tuberculosis control. The study is based on nationwide IS6110-RFLP genotyping of tuberculosis cases from 1992 through 2004, corresponding to 98% of culture verified cases. Of 3988 cases, 45% were non-clustered. Both Danes and immigrants had a peak incidence of non-clustered tuberculosis at older ages, 80-89 years (4.3 cases/10(5) population/year) and 60-69 years (28.8 cases/10(5) population/year), respectively. In addition, immigrants had a peak at 20-29 years (43.2 cases/10(5) inhabitants/year). In Danes, the incidence of non-clustered tuberculosis decreased during the study period and was predominantly found in elderly persons, presumably reactivating infection acquired during 1910-40, when tuberculosis incidence was high. In immigrants, the incidence was high at all ages, presumably reflecting reactivation of imported infections. In the future, the number of non-clustered tuberculosis cases will decrease, as older Danes die, and as time since primary infection increases for immigrants residing in Denmark. TB control should include focus on non-clustered cases.

Differential findings regarding molecular epidemiology of tuberculosis between two consecutive periods in the context of steady increase of immigration

The demographic characteristics of the population of Madrid, with a steady increase in immigrants, from 4.7% in 1998 to 17.4% in 2007, provide an opportunity to study in depth the transmission of TB. Our aim was to compare two 3-year longitudinal molecular studies of TB to define transmission patterns and predictors of clustering. Two prospective population-based molecular and epidemiological studies (2002-2004 and 2005-2007) of TB patients were conducted in nine urban districts in Madrid using the same methodology. During the period 2002-2007, 2248 cases of TB were reported, and the incidence decreased from 23.5 per 100,000 in 2002 to 20.8 in 2007 (p <0.001). A total of 1269 isolates were molecularly characterized and included in the study. The comparison between the two periods showed that the percentage of foreign-born patients among TB cases increased from 36.2% to 45.7% (p <0.001). Furthermore, the percentage of clustered cases decreased (36.6% vs. 30.6%; p 0.028), and this decline was associated with a decrease of clustered cases among men and people under 35 years. We also observed a decrease in cases belonging to clusters containing ≥ 6 people (14.2% vs. 8.2%; p <0.001), and in cases belonging to mixed clusters containing Spanish-born and foreign-born patients (18.5% vs. 11.1%, p <0.001). Our molecular epidemiology study provides clues to interpret the decrease in the incidence of TB in a context of steady increase of immigration. In our region, the decrease in the incidence of TB can be explained predominantly as a result of a decline in recent transmission.