Proximate determinants of tuberculosis in Indigenous peoples worldwide: a systematic review

Using Geographic Disaggregation to Compare Tuberculosis Epidemiology Among American Indian and Alaska Native Persons-USA, 2010-2020

BACKGROUND

American Indian and Alaska Native (AIAN) populations are frequently associated with the highest rates of tuberculosis (TB) disease of any racial/ethnic group in the USA. We systematically investigated variation in patterns and potential drivers of TB epidemiology among geographically distinct AIAN subgroups.

METHODS

Using data reported to the National Tuberculosis Surveillance System during 2010-2020, we applied a geographic method of data disaggregation to compare annual TB incidence and the frequency of TB patient characteristics among AIAN persons in Alaska with AIAN persons in other states. We used US Census data to compare the prevalence of substandard housing conditions in AIAN communities in these two geographic areas.

RESULTS

The average annual age-adjusted TB incidence among AIAN persons in Alaska was 21 times higher than among AIAN persons in other states. Compared to AIAN TB patients in other states, AIAN TB patients in Alaska were associated with significantly higher frequencies of multiple epidemiologic TB risk factors (e.g., attribution of TB disease to recent transmission, previous diagnosis of TB disease) and significantly lower frequencies of multiple clinical risk factors for TB disease (e.g., diagnosis with diabetes mellitus, end-stage renal disease). Occupied housing units in AIAN communities in Alaska were associated with significantly higher frequencies of multiple measures of substandard housing conditions compared to AIAN communities in other states.

CONCLUSIONS

Observed differences in patient characteristics and substandard housing conditions are consistent with contrasting syndromes of TB epidemiology in geographically distinct AIAN subgroups and suggest ways that associated public health interventions could be tailored to improve efficacy.

Sociodemographic factors associated with the success or failure of anti-tuberculosis treatment in the Chiapas Highlands, Mexico, 2019-2022

OBJECTIVE

To estimate the incidence rate of tuberculosis (TB) in the Highlands (Tsotsil-Tseltal) region of Chiapas and to analyze sociodemographic factors that might influence the success of anti-TB treatment from the period of January 2019 to June 2022.

METHODS

Retrospective study in which the TB databases of the National Epidemiological Surveillance System (SINAVE) were analyzed. TB incidence rates were calculated based on the number of registered TB cases and estimated annual populations. The success-failure of anti-TB treatment was analyzed according to sociodemographic indicators, degree of concentration of indigenous population of the municipality of residence and admission to SINAVE.

RESULTS

Two hundred thirty-three cases were analyzed. The variables associated to a lower success rate of treatment against TB were: living in a municipality with high-very high concentration of indigenous population, being indigenous, having a primary school education or lower, and agricultural occupation. The number of TB diagnosed from 2020-2022 and the incidence rates from 2020-2021 decreased significantly compared to 2019.

CONCLUSIONS

It is necessary to strengthen the follow-up of TB cases in the region, mainly in areas with high-very high indigenous concentration, in people with low levels of education and engaged in agricultural work.

Spatial-temporal evolution of tuberculosis incidence rates in indigenous and non-indigenous people of Brazil, from 2011 to 2022

OBJECTIVE

To describe the space-time evolution of TB incidence rates (TI) in indigenous and non-indigenous people, according to the Federative Units (UF) of Brazil, from 2011 to 2022.

METHODS

Ecological, temporal, and spatial study on new tuberculosis cases in Brazil among indigenous and non-indigenous populations. Data from the Notifiable Diseases Information System (Sinan) were collected from 2011 to 2022 and stratified by Federal Unit, explored and statistically analyzed using R software version 4.2.3.

RESULTS

The mean TI among indigenous populations in Brazil was 71.7 new cases per 100,000 inhabitants, while for non-indigenous populations it was 28.6/100,000 inhabitants. The regions of the country that presented the highest (mean) incidence among indigenous populations were: Central-West (102.8/100,000 inhabitants), Southeast (99.6/100,000 inhabitants), and North (79.9/100,000 inhabitants). For non-indigenous populations the highest incidence was in the North region (36.5/100,000 inhabitants), followed by the Southeast (31.3/100,000), and the Northeast (27,4/100,000 inhabitants). The analysis showed that the highest incidence of TB cases among indigenous populations occurred in the states of: SP, RO, RJ, MS, MT e PA.

CONCLUSION

High incidence of the disease compared to the non-indigenous population show the need for a specific approach to address the health needs of these populations. Regional disparities in incidence indicate the need to address socioeconomic and infrastructure issues that affect the health of indigenous populations.

Burden of tuberculosis among vulnerable populations worldwide: an overview of systematic reviews

BACKGROUND

Tuberculosis is a communicable disease of public health concern that inequitably impacts the most vulnerable populations worldwide. Vulnerable populations are those with a high risk for tuberculosis disease and whose disadvantaged or marginalised socioeconomic position limits their access to the health system. We conducted an overview of reviews that aimed to assess the burden (ie, prevalence and incidence) of tuberculosis disease among 12 vulnerable populations globally.

METHODS

We did an overview of reviews using a systematic search in MEDLINE, Embase, and the Cochrane Database for Systematic Reviews for articles published in English, French, and Chinese, from Jan 1, 2010 to March 8, 2023. We did an initial search on Oct 28, 2021, and updated our search on March 8, 2023. We included systematic and scoping reviews reporting on the prevalence or incidence of active tuberculosis among 12 vulnerable populations. Evidence gaps were supplemented with primary or secondary database studies. Study characteristics and outcome data related to tuberculosis burden were tabulated, including prevalence ratios and incidence rate ratios, and evidence was synthesised narratively. This trial is registered with PROSPERO (CRD42022324421).

FINDINGS

We screened 13 169 citations and included 44 publications (23 reviews and 21 primary or database studies) in the final synthesis. The comprehensiveness and methodological quality of the evidence differed across population groups. Prevalence of more than 1000 cases per 100 000 were reported in all vulnerable populations. On the basis of pooled estimates, prevalence ratios were often more than 25 among people experiencing homelessness, incarcerated populations, refugees, asylum seekers, and people living with HIV compared with the general population. Incidence was infrequently reported, with the best-available incidence rate ratios documented for people who were incarcerated. There was scarce evidence specific to miners, nomadic populations, sex workers, men who have sex with men, and transgender individuals.

INTERPRETATION

The burden of tuberculosis is substantially higher among vulnerable populations than general populations, suggesting a need for improved integration of these groups, including dedicated efforts for their identification, targeted screening and prevention measures, as well as treatment support.

FUNDING

WHO.

Transmission Dynamics of a Mycobacterium tuberculosis Complex Outbreak in an Indigenous Population in the Colombian Amazon Region

Whole genome sequencing (WGS) has become the main tool for studying the transmission of Mycobacterium tuberculosis complex (MTBC) strains; however, the clonal expansion of one strain often limits its application in local MTBC outbreaks. The use of an alternative reference genome and the inclusion of repetitive regions in the analysis could potentially increase the resolution, but the added value has not yet been defined. Here, we leveraged short and long WGS read data of a previously reported MTBC outbreak in the Colombian Amazon Region to analyze possible transmission chains among 74 patients in the indigenous setting of Puerto Nariño (March to October 2016). In total, 90.5% (67/74) of the patients were infected with one distinct MTBC strain belonging to lineage 4.3.3. Employing a reference genome from an outbreak strain and highly confident single nucleotide polymorphisms (SNPs) in repetitive genomic regions, e.g., the proline-glutamic acid/proline-proline-glutamic-acid (PE/PPE) gene family, increased the phylogenetic resolution compared to a classical H37Rv reference mapping approach. Specifically, the number of differentiating SNPs increased from 890 to 1,094, which resulted in a more granular transmission network as judged by an increasing number of individual nodes in a maximum parsimony tree, i.e., 5 versus 9 nodes. We also found in 29.9% (20/67) of the outbreak isolates, heterogenous alleles at phylogenetically informative sites, suggesting that these patients are infected with more than one clone. In conclusion, customized SNP calling thresholds and employment of a local reference genome for a mapping approach can improve the phylogenetic resolution in highly clonal MTBC populations and help elucidate within-host MTBC diversity. IMPORTANCE The Colombian Amazon around Puerto Nariño has a high tuberculosis burden with a prevalence of 1,267/100,000 people in 2016. Recently, an outbreak of Mycobacterium tuberculosis complex (MTBC) bacteria among the indigenous populations was identified with classical MTBC genotyping methods. Here, we employed a whole-genome sequencing-based outbreak investigation in order to improve the phylogenetic resolution and gain new insights into the transmission dynamics in this remote Colombian Amazon Region. The inclusion of well-supported single nucleotide polymorphisms in repetitive regions and a de novo-assembled local reference genome provided a more granular picture of the circulating outbreak strain and revealed new transmission chains. Multiple patients from different settlements were possibly infected with at least two different clones in this high-incidence setting. Thus, our results have the potential to improve molecular surveillance studies in other high-burden settings, especially regions with few clonal multidrug-resistant (MDR) MTBC lineages/clades.

Health inequalities in infectious diseases: a systematic overview of reviews

OBJECTIVES

The aim of this systematic overview of reviews was to synthesise available evidence on inequalities in infectious disease based on three dimensions of inequalities; inclusion health groups, protected characteristics and socioeconomic inequalities.

METHODS

We searched MEDLINE, Embase, Web of Science and OpenGrey databases in November 2021. We included reviews published from the year 2000 which examined inequalities in the incidence, prevalence or consequences of infectious diseases based on the dimensions of interest. Our search focused on tuberculosis, HIV, sexually transmitted infections, hepatitis C, vaccination and antimicrobial resistance. However, we also included eligible reviews of any other infectious diseases. We appraised the quality of reviews using the Assessment of Multiple Systematic Reviews V.2 (AMSTAR2) checklist. We conducted a narrative data synthesis.

RESULTS

We included 108 reviews in our synthesis covering all the dimensions of inequalities for most of the infectious disease topics of interest, however the quality and volume of review evidence and consistency of their findings varied. The existing literature reviews provide strong evidence that people in inclusion health groups and lower socioeconomic status are consistently at higher risk of infectious diseases, antimicrobial resistance and incomplete/delayed vaccination. In the protected characteristics dimension, ethnicity, and sexual orientation are important factors contributing to inequalities across the various infectious disease topics included in this overview of reviews.

CONCLUSION

We identified many reviews that provide evidence of various types of health inequalities in different infectious diseases, vaccination, and antimicrobial resistance. We also highlight areas where reviews may be lacking. The commonalities in the associations and their directions suggest it might be worth targeting interventions for some high risk-groups that may have benefits across multiple infectious disease outcomes rather than operating purely in infectious disease siloes.

Higher native Peruvian genetic ancestry proportion is associated with tuberculosis progression risk

We investigated whether ancestry-specific genetic factors affect tuberculosis (TB) progression risk in a cohort of admixed Peruvians. We genotyped 2,105 patients with TB and 1,320 household contacts (HHCs) who were infected with Mycobacterium tuberculosis (M. tb) but did not develop TB and inferred each individual’s proportion of native Peruvian genetic ancestry. Our HHC study design and our data on potential confounders allowed us to demonstrate increased risk independent of socioeconomic factors. A 10% increase in individual-level native Peruvian genetic ancestry proportion corresponded to a 25% increased TB progression risk. This corresponds to a 3-fold increased risk for individuals in the highest decile of native Peruvian genetic ancestry versus the lowest decile, making native Peruvian genetic ancestry comparable in effect to clinical factors such as diabetes. Our results suggest that genetic ancestry is a major contributor to TB progression risk and highlight the value of including diverse populations in host genetic studies.

Our understanding of how genetic differences among human populations may affect susceptibility to infectious diseases is very limited. Asgari et al. show that the proportion of native genetic ancestry in contemporary Peruvians affects the risk of progression from latent to active tuberculosis even after accounting for differences in socio-demographic factors.

Risk factors for TB in Australia and their association with delayed treatment completion

BACKGROUND: Australia has a low incidence of TB and has committed to eliminating the disease. Identification of risk factors associated with TB is critical to achieving this goal.METHODS: We undertook a prospective cohort study involving persons receiving TB treatment in four Australian jurisdictions. Risk factors and their association with delayed treatment completion (treatment delayed by at least 1 month) were analysed using univariate analyses and multivariate logistic regression.RESULTS: Baseline surveys were completed for 402 persons with TB. Most (86.1%) were born overseas. Exposure to a person with TB was reported by 19.4%. Diabetes mellitus (10.2%), homelessness (9.2%), cigarette smoking (8.7%), excess alcohol consumption (6.0%) and mental illness (6.2%) were other common risk factors. At follow-up, 24.8% of patients had delayed treatment completion, which was associated with adverse events (34.1%, aOR 6.67, 95% CI 3.36-13.27), excess alcohol consumption (6.0%, aOR 21.94, 95% CI 6.03-79.85) and HIV co-infection (2.7%, aOR 8.10, 95% CI 1.16-56.60).CONCLUSIONS: We identified risk factors for TB and their association with delayed treatment completion, not all of which are routinely collected for surveillance purposes. Recognition of these risk factors should facilitate patient-centred care and assist Australia in reaching TB elimination.

Evaluating tobacco industry 'transformation': a proposed rubric and analysis

Some tobacco companies claim they are 'transforming' by adopting harm reduction goals or even seeking to achieve a 'smokefree' world. What characterises transformation and whether companies can or are transforming is unclear. Nevertheless, such claims are gaining traction. We critically investigated tobacco industry transformation by exploring the definition and criteria for evaluating transformation, and assessed whether transformation is occurring and feasible.Companies' transformation claims centre on increasing sales of new tobacco and nicotine products like e-cigarettes ('new products') with little attention to reducing sales of more hazardous smoked and oral products ('conventional products').We define a transforming tobacco company as one demonstrating substantial, rapid and verifiable progress towards eliminating the production and sale of conventional tobacco products within 5 years in all markets where it operates.We found no evidence any tobacco company is meeting the three essential criteria of rapidly progressing towards eliminating conventional products, ceasing to obstruct effective tobacco control measures and taking action to minimise smoking uptake and disparities. While some companies are developing new product portfolios, their actions are more consistent with profit maximisation than eliminating conventional product use. This approach is best described as 'pseudo-transformation', designed to delay implementation of effective tobacco control policies. In addition, our analysis suggests replacing conventional products with new nicotine products is unlikely to be a viable long-term business model.Public health practitioners should not rely on tobacco industry claims but should lead the transformation debate, establish credible definitions and criteria, and monitor and assess whether transformation is occurring.

High incidence of pulmonary tuberculosis in an indigenous Saharia tribe in Madhya Pradesh, central India-A prospective cohort study

BACKGROUND

Lack of TB incidence data is an important evidence gap among Saharia-a high TB burden indigenous community in Madhya Pradesh, central India. The present study was undertaken to calculate the incidence of pulmonary tuberculosis in this tribe.

OBJECTIVE

To calculate the incidence of pulmonary tuberculosis (PTB) among the Saharia tribal population in Madhya Pradesh, central India.

METHODS

A prospective cohort study was conducted among the Saharia tribal population (aged 15 years and above) of Shivpuri district in Madhya Pradesh state in central India. A total of 9,756 individuals were screened for TB in the baseline TB prevalence survey during 2012-13. All available household members were screened for symptoms suggestive of pulmonary TB (presumptive TB). Two sputum specimens were collected from persons having symptoms suggestive of TB and examined by smear and culture tests. A cohort of all non-TB individuals in the baseline survey was followed-up for one year and re-screened for the sysmptoms of PTB in the year 2014-15. Based on the data collected, the incidence of TB over one year period was estimated per 100,000 population.

RESULTS

A total of 9756 and 9044 individuals (≥ 15 years) were screened for symptoms suggestive of PTB during baseline and endline surveys respectively. The sputum specimens of presumptive TB cases were collected and examined by smear and culture tests. The overall incidence of bacteriologically positive (smear and/or culture) PTB over one year period was 1504 (95% Confidence Interval (CI): 1273-1776) per 100,000 in the study population, the incidence of smear-positive PTB was 1106 (95% CI: 910-1343), and the incidence of culture-positive PTB was 1084 (95% CI: 890-1319) per 100,000 population. The incidence for both smear and culture-positive PTB was 686 (95% CI: 535-878) per 100,000 population in the year 2014-15. The incidence of PTB was 2.8 times higher in males compared to females (2259 vs 807 per 100,000) and was positively correlated with age.

CONCLUSION

The findings of the study, the first of its kind in the Saharia tribal population, indicate a high incidence of TB in this tribal community thereby highlighting the urgent need for focused and intensified efforts to achieve the goal of TB elimination in the country.

Tuberculosis care designed with barramarrany (family): Participatory action research that prioritised partnership, healthy housing and nutrition

Issue addressed.

Ongoing tuberculosis (TB) transmission in Aboriginal communities in Australia is unfair and unacceptable. Redressing the inequity in TB affecting Aboriginal peoples is a priority in Australia's Strategic Plan for Tuberculosis Control. Improving TB care needs not to just identify barriers but do something about them. Privileging the voices of Aboriginal people affected by TB is essential to identify effective and enabling strategies.

Active screening for tuberculosis in high-incidence Inuit communities in Canada: a cost-effectiveness analysis

Background:

Active screening for tuberculosis (TB) involves systematic detection of previously undiagnosed TB disease or latent TB infection (LTBI). It may be an important step toward elimination of TB among Inuit in Canada. We aimed to evaluate the cost-effectiveness of community-wide active screening for TB infection and disease in 2 Inuit communities in Nunavik.

Methods:

We incorporated screening data from the 2 communities into a decision analysis model. We predicted TB-related health outcomes over a 20-year time frame, beginning in 2019. We assessed the cost-effectiveness of active screening in the presence of varying outbreak frequency and intensity. We also considered scenarios involving variation in timing, impact and uptake of screening programs.

Results:

Given a single large outbreak in 2019, we estimated that 1 round of active screening reduced TB disease by 13% (95% uncertainty range −3% to 27%) and was cost saving compared with no screening, over 20 years. In the presence of simulated large outbreaks every 3 years thereafter, a single round of active screening was cost saving, as was biennial active screening. Compared with a single round, we also determined that biennial active screening reduced TB disease by 59% (95% uncertainty range 52% to 63%) and was estimated to cost Can$6430 (95% uncertainty range −$29 131 to $13 658 in 2019 Can$) per additional active TB case prevented. With smaller outbreaks or improved rates of treatment initiation and completion for people with LTBI, we determined that biennial active screening remained reasonably cost-effective compared with no active screening.

Interpretation:

Active screening is a potentially cost-saving approach to reducing disease burden in Inuit communities that have frequent TB outbreaks.

Tuberculosis in Australia's tropical north: a population-based genomic epidemiological study

BACKGROUND

The Northern Territory (NT) has the highest tuberculosis (TB) rate of all Australian jurisdictions. We combined TB public health surveillance data with genomic sequencing of Mycobacterium tuberculosis isolates in the tropical 'Top End' of the NT to investigate trends in TB incidence and transmission.

METHODS

This retrospective observational study included all 741 culture-confirmed cases of TB in the Top End over three decades from 1989-2020. All 497 available M. tuberculosis isolates were sequenced. We used contact tracing data to define a threshold pairwise SNP distance for hierarchical single linkage clustering, and examined putative transmission clusters in the context of epidemiologic information.

FINDINGS

There were 359 (48%) cases born overseas, 329 (44%) cases among Australian First Nations peoples, and 52 (7%) cases were Australian-born and non-Indigenous. The annual incidence in First Nations peoples from 1989-2019 fell from average 50.4 to 11.0 per 100,000 (P<0·001). First Nations cases were more likely to die from TB (41/329, 12·5%) than overseas-born cases (11/359, 3·1%; P<0·001). Using a threshold of ≤12 SNPs, 28 clusters of between 2-64 individuals were identified, totalling 250 cases; 214 (86%) were First Nations cases and 189 (76%) were from a remote region. The time between cases and past epidemiologically- and genomically-linked contacts ranged from 4·5 months to 24 years.

INTERPRETATION

Our findings support prioritisation of timely case detection, contact tracing augmented by genomic sequencing, and latent TB treatment to break transmission chains in Top End remote hotspot regions.

The prevalence of tuberculosis, malaria and soil-transmitted helminth infection in minority indigenous people of Southeast Asia and the Western Pacific: protocol for a systematic review and meta-analysis

BACKGROUND

Infectious diseases such as tuberculosis (TB), malaria and soil-transmitted helminthiasis continue to impose a significant global health burden and socio-economic impact. Globally, minority indigenous people are disproportionately affected by poverty and are shown to experience a disparate burden of disease and poorer health outcomes than the comparative majority population. Despite these inequalities, countries rarely systematically compile epidemiological data disaggregated by ethnicity to enable the extent of the differential to be quantified.

METHODS

The systematic review will be reported in accordance with The Preferred Reporting Items for Systematic Review and Meta- Analyses (PRISMA) guidelines. Systematic searches will be conducted in EMBASE, Medline, Scopus and Web of Science for studies reporting data which enable the prevalence of TB, malaria, and/or soil-transmitted helminth (STH) infections amongst minority indigenous populations within the Southeast Asia Region (SEAR) and Western Pacific Region (WPR) to be calculated. Where studies provide data on disease prevalence for both minority indigenous and other populations within the same study, a comparative analysis will be undertaken. In addition to a narrative synthesis, where sufficient data are available, a random-effects meta-analysis will be conducted to obtain a pooled estimate value for each disease/infection by country and mortality stratum. Heterogeneity between studies will be examined using the Cochran's Q test and quantitatively measured by the index of heterogeneity squared (I2) statistics. The methodological quality of the included studies will be assessed using a modified Newcastle-Ottawa Scale.

DISCUSSION

This systematic review aims to analyse the available data on the prevalence of TB, malaria and STH infections within minority indigenous populations of the SEAR and WPR.

REGISTRATION

Open Science Framework registration: osf.io/m6sqc.

ESAT-6 and Ag85A Synthetic Peptides as Candidates for an Immunodiagnostic Test in Children with a Clinical Suspicion of Tuberculosis

Background

Tuberculosis (TB) is being underdetected in children as most are smear-negative. This work was aimed at evaluating ESAT-6 and Ag85A synthetic peptides' serodiagnostic potential for diagnosing children having a clinical suspicion of TB.

Methods

The study involved 438 children: 77 Creole nonindigenous (13 suspected of having TB and 64 healthy ones) and 361 Warao indigenous children (39 suspected of TB and 322 healthy children). The approach's diagnostic information was compared using operational characteristics and receiver-operating characteristic (ROC) curves.

Results

Ag85A P-29879 had 94.6% sensitivity (AUC = 0.741: 0.651 to 0.819 95% CI) in indigenous children. ESAT-6 P-12036 and P-12037 had 100% and 92.3% of sensitivity (AUC = 0.929: 0.929: 0.846 to 0.975 95% CI and 0.791: 63.9 to 98.7 95% CI, respectively) in Creole children. ESAT-6 peptides also allowed a differentiation between children with TB and healthy ones.

Conclusions

Further validation of this approach could lead to developing a complementary tool for rapid TB diagnosis in children.

Ethnic disparities in tuberculosis incidence and related factors among indigenous and other communities in ethnically diverse Suriname

Background

In Suriname, a country home to many ethnic groups, a high incidence of tuberculosis (TB) has been found among Indigenous Trio Amerindians. However, whether wider ethnic disparities in TB incidence and its associated risk factors (e.g., diabetes mellitus and HIV) exist in Suriname, is not known. We sought to investigate disparities in TB incidence and its risk factors on ethnicity in Suriname, as this could give way to targeted TB intervention programs.

Methods

Anonymized patient data from 2011 to 2015 was extracted from the National TB Registry and analyzed. Differences in the five-year incidence rates of TB for the six largest ethnic groups-Creole, Hindustani, Indigenous, Javanese, Maroon, and Mixed-were assessed using a chi-square goodness-of-fit test, and TB patient differences regarding ethnicity were evaluated for selected factors using a multinomial logistic regression with Creole patients as reference.

Results

662 Patients were eligible for analyses with the following ethnic makeup: Creole (36.4%), Hindustani (15.6%), Indigenous (8.6%), Javanese (10.6%), Maroon (15.1%), and Mixed ethnicity (13.7%). Differences in five-year incidence rates for TB were significant, χ ²(5, N = 662) = 244.42, p < .001, and the highest TB rates were found for Indigenous (280 per 100,000) and Creole people (271 per 100,000). HIV coinfection was a TB risk factor for Creoles (38.2% of these patients were HIV positive). Several variables (i.e., those for drug use) had high levels of incomplete or missing data.

Conclusions

Our study has demonstrated that ethnic disparities in tuberculosis incidence exist in Suriname and that they are associated with specific, known risk factors such as HIV (especially for Creole people). For Indigenous people, risk factors may include diminished access to health care facilities and low socioeconomic status. However, direct data on these factors was unavailable. These findings call for targeted national intervention programs-with special attention given to the vulnerabilities of susceptible ethnic groups-and improved data collection.

Tuberculosis care cascade for the indigenous population in Colombia: an operational research study

Objective.

Construct and evaluate the care cascade for pulmonary tuberculosis in the indigenous population of the department of Cauca (Colombia) and identify existing gaps.

Methods.

Mixed-methods sequential explanatory design. In the first phase, the pulmonary tuberculosis care cascade for the indigenous population of Cauca was evaluated. Data were obtained from secondary sources and all cases diagnosed from 1 January 2016 to 31 December 2017 were included. In the second phase, semi-structured interviews were done with nine program coordinators and 11 nursing auxiliaries to explain identified gaps. Absolute and percentage values were estimated for each of the steps and gaps in the care cascade. Quantitative and qualitative results were triangulated.

Results.

In 2016 and 2017, an estimated 202 patients with respiratory symptoms were expected to be positive and 106 cases of pulmonary tuberculosis were reported among the indigenous population of the department of Cauca. A gap of 47.5% was found for diagnosis, since only 52.5% of subjects were diagnosed in health services. This gap was explained by poor quality of samples and flawed smear techniques; flaws in correct identification of patients with respiratory symptoms; limited access to diagnostic methods, such as culture and molecular tests; and limited training and high turnover of personnel in health service provider institutions.

Conclusions.

The tuberculosis control program should focus actions on bridging the gap in case detection in the indigenous population.

Social and behavioral risk reduction strategies for tuberculosis prevention in Canadian Inuit communities: a cost-effectiveness analysis

BACKGROUND

Tuberculosis (TB) is an important public health problem in Inuit communities across Canada, with an annual incidence rate in 2017 that was nearly 300 times higher than in Canadian-born non-Indigenous individuals. Social and behavioral factors that are prevalent in the North, such as commercial tobacco use, excessive alcohol use, food insecurity and overcrowded housing put individuals at higher risk for TB morbidity and mortality. We examined the potential impact of mitigation strategies for these risk factors, in reducing TB burden in this setting.

METHODS

We created a transmission model to simulate the epidemiology of TB in Nunavut, Canada. We then used a decision analysis model to assess the potential impact of several evidence-based strategies targeting tobacco use, excessive alcohol use, food insecurity and overcrowded housing. We predicted TB incidence, TB-related deaths, quality adjusted life years (QALYs), and associated costs and cost-effectiveness over 20 years. All costs were expressed in 2018 Canadian dollars.

RESULTS

Compared to a status quo scenario with no new interventions for these risk factors, the reduction strategy for tobacco use was most effective and cost-effective, reducing TB incidence by 5.5% (95% uncertainty range: 2.7-11%) over 20 years, with an estimated cost of $95,835 per TB case prevented and $49,671 per QALY gained. The addition of the food insecurity reduction strategy reduced incidence by a further 2% (0.5-3%) compared to the tobacco cessation strategy alone, but at significant cost.

CONCLUSIONS

Strategies that aim to reduce commercial tobacco use and improve food security will likely lead to modest reductions in TB morbidity and mortality. Although important for the communities, strategies that address excess alcohol use and overcrowding will likely have a more limited impact on TB-related outcomes at current scale, and are associated with much higher cost. Their benefits will be more substantial with scale up, which will also likely have important downstream impacts such as improved mental health, educational attainment and food security.

Identification of a predominant genotype of Mycobacterium tuberculosis in Brazilian indigenous population

After nearly a century of vaccination and six decades of drug therapy, tuberculosis (TB) kills more people annually than any other infectious disease. Substantial challenges to disease eradication remain among vulnerable and underserved populations. The Guarani-Kaiowá people are an indigenous population in Paraguay and the Brazilian state of Mato Grosso do Sul. This community, marginalized in Brazilian society, experiences severe poverty. Like other South American indigenous populations, their TB prevalence is high, but the disease has remained largely unstudied in their communities. Herein, Mycobacterium tuberculosis isolates from local clinics were whole genome sequenced, and a population genetic framework was generated. Phylogenetics show M. tuberculosis isolates in the Guarani-Kaiowá people cluster away from selected reference strains, suggesting divergence. Most cluster in a single group, further characterized as M. tuberculosis sublineage 4.3.3. Closer analysis of SNPs showed numerous variants across the genome, including in drug resistance-associated genes, and with many unique changes fixed in each group. We report that local M. tuberculosis strains have acquired unique polymorphisms in the Guarani-Kaiowá people, and drug resistance characterization is urgently needed to inform public health to ensure proper care and avoid further evolution and spread of drug-resistant TB.

[Tuberculosis care cascade for the indigenous population in Colombia: an operational research studyCascata de atenção da tuberculose para os povos indígenas na Colômbia: pesquisa operacional]

Objetivo

Construir y evaluar la cascada de atención de la tuberculosis pulmonar en la población indígena del departamento del Cauca (Colombia) e identificar las brechas existentes.

Métodos

Metodología mixta con diseño secuencial explicativo. En la primera fase se evaluó la cascada de atención de la tuberculosis pulmonar para la población indígena del Cauca. Se obtuvieron datos de fuentes secundarias y se incluyeron todos los casos diagnosticados entre el 1 de enero del 2016 y el 31 de diciembre de 2017. En la segunda fase, se aplicaron entrevistas semiestructuradas a nueve coordinadores de programa y 11 auxiliares de enfermería para explicar las brechas identificadas. Se estimaron los valores absolutos y porcentuales en cada uno de los pasos y las brechas de la cascada de atención. Se triangularon los resultados cuantitativos y cualitativos.

Resultados

Durante 2016 y 2017 se estimaron 202 sintomáticos respiratorios esperados positivos y se notificaron 106 casos de tuberculosis pulmonar en la población indígena del departamento del Cauca. Se encontró una brecha de 47,5% para el diagnóstico, ya que solo 52,5% de los sujetos recibieron el diagnóstico en los servicios de salud. Las explicaciones a esta brecha fueron la mala calidad de muestras y fallas en la técnica del extendido, fallas en la correcta identificación del sintomático respiratorio, acceso limitado a métodos diagnósticos como cultivo y pruebas moleculares, así como capacitación escasa y rotación alta de personal al interior de las instituciones prestadoras de servicios de salud.

Conclusiones

Las acciones del programa de control de tuberculosis deben enfocarse en reducir la brecha de detección de casos en la población indígena.

The contribution of stigma to the transmission and treatment of tuberculosis in a hyperendemic indigenous population in Brazil

Background

The Guarani-Kaiowá are Brazil's second-largest indigenous group. Average annual tuberculosis (TB) incidence rates among the Guarani-Kaiowá are nearly 400/100,000 in Mato Grosso do Sul state, ten times the national average. Although stigma is considered crucial for TB control in indigenous communities, few studies have investigated TB stigma among indigenous populations. This study sought to understand the role of TB-related stigma and perceptions of TB in maintaining hyperendemic TB transmission in the Guarani-Kaiowá communities.

Methods

Various forms of stigma were explored through semi-structured interviews with 19 patients, 11 relatives, and 23 community members. Patients were identified from the registry of the healthcare service. Community members, selected by snowball sampling, were matched by gender and village of residence. Interviews were conducted in Guarani and Portuguese and later translated into English. Framework analysis was performed using NVivo.

Results

Traditional beliefs of a weakening of the body allowing the disease to enter were common, but the exact mechanism of transmission was unknown. Strong community/public stigma associated TB with uncleanliness, abuse, and irresponsibility. Anticipated stigma led to significant treatment delays for fear of exclusion and losing employment. While most patients felt supported by their families, nearly all patients related experienced/enacted stigma in the community such as gossip, avoidance, and social exclusion, leading to long-lasting internalized/self-stigma. Secondary stigmatization of relatives was widespread, and blanket latent TB infection (LTBI) treatment of patients’ households was a contributing factor in treatment delay. The healthcare service unnecessarily added to stigmatization by enforcing separate utensils and sleeping arrangements for patients.

Conclusions

Our findings suggest that stigma is a driver for treatment delay and continued transmission of TB in the community. The stigmatization of TB was rooted in a poor understanding of TB transmission, partly because of incorrect orientation by the healthcare service. Interventions to reduce TB-associated stigma are urgently needed.

[Factors associated with unsuccessful treatment of patients with drug-sensitive tuberculosis in Paraguay]

Objetivo.

Determinar los factores asociados con el tratamiento no exitoso en pacientes diagnosticados con tuberculosis (TB) sensible en Paraguay.

Métodos.

Estudio de cohorte retrospectivo, con datos recolectados del programa nacional entre enero de 2016 y marzo de 2017. Se definió tratamiento no exitoso como pacientes que se perdieron en el seguimiento, fracasaron en el tratamiento o fallecieron. Los factores asociados con tratamiento no exitoso se determinaron con regresión de Poisson; se estimó el riesgo relativo (RR) y el intervalo de confianza de 95% (IC95%) ajustados por región sanitaria.

Resultados.

Se estudiaron 3 034 casos: 2 189 (72,1%) tuvieron tratamiento exitoso (curados: 1 221 [40,2%], tratamiento completo: 968 [31,9%]) y 845 (27,9%) presentaron tratamiento no exitoso (fracaso: 40 [1,3%], pérdida de seguimiento: 466 [15,4%] y fallecidos: 339 [11,2%]). Los factores asociados a tratamiento no exitoso fueron hombres 1,28 (1,14- 1,42), indígenas 1,30 (1,09- 1,54), sin reporte de área de residencia 1,27 (1,02- 1,57), coinfección TB/VIH 1,97 (1,63- 2,38), adicción a drogas ilícitas 1,38 (1,16- 1,63), consumo de alcohol 1,25 (1,02- 1,52), ser previamente tratado 1,23 (1,10- 1,38) y sin datos de supervisión del tratamiento 4,92 (3,69- 6,56). Como factores protectores se consideran ser persona privada de libertad 0,65 (0,47- 0,89), así como la comorbilidad TB/diabetes 0,80 (0,67- 0,95).

Conclusión.

Paraguay presenta un alto porcentaje de tratamiento no exitoso en casi todo el país, sin alcanzar la meta propuesta por la Organización Mundial de la Salud. Los factores de riesgo asociados como infección por el virus de la inmunodeficiencia humana (VIH), consumo de drogas licitas e ilícitas y el ser indígena revela que es necesario revisar las estrategias dirigidas con abordaje interinstitucional.

Dispersal of Mycobacterium tuberculosis Driven by Historical European Trade in the South Pacific

Mycobacterium tuberculosis (Mtb) is a globally distributed bacterial pathogen whose population structure has largely been shaped by the activities of its obligate human host. Oceania was the last major global region to be reached by Europeans and is the last region for which the dispersal and evolution of Mtb remains largely unexplored. Here, we investigated the evolutionary history of the Euro-American L4.4 sublineage and its dispersal to the South Pacific. Using a phylodynamics approach and a dataset of 236 global Mtb L4.4 genomes we have traced the origins and dispersal of L4.4 strains to New Zealand. These strains are predominantly found in indigenous Māori and Pacific people and we identify a clade of European, likely French, origin that is prevalent in indigenous populations in both New Zealand and Canada. Molecular dating suggests the expansion of European trade networks in the early 19th century drove the dispersal of this clade to the South Pacific. We also identify historical and social factors within the region that have contributed to the local spread and expansion of these strains, including recent Pacific migrations to New Zealand and the rapid urbanization of Māori in the 20th century. Our results offer new insight into the expansion and dispersal of Mtb in the South Pacific and provide a striking example of the role of historical European migrations in the global dispersal of Mtb.