Genetic polymorphism and immune response to tuberculosis in indigenous populations: a brief review

Differential NRAMP1gene's D543N genotype frequency: Increased risk of contracting tuberculosis among Venezuelan populations

NRAMP1 and VDR gene polymorphisms have been variably associated with susceptibility to tuberculosis (TB) amongst populations having different genetic background. NRAMP1 and VDR gene variants' association with susceptibility to active infection by Mycobacterium tuberculosis (Mtb) was analyzed in the Warao Amerindian population, an ethnic population from Venezuela's Orinoco delta region. Genomic DNA was extracted from individuals with and without TB to evaluate genetic polymorphism by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Four NRAMP1 gene polymorphisms were analyzed: D543N (rs17235409), 3' UTR (rs17235416), INT4 (rs3731865), and 274C/T (rs2276631), and one VDR gene polymorphism: FokI (rs2228570). The results showed that the genotypes D543N-A/A, 3'UTR-TGTG+/+, INT4-C/C, and 274C/T-T/T of known polymorphism in the NRAMP1 gene, as well as the genotypes FokI-F/f and FokI-f/f in the VDR gene were most often found in indigenous Warao with active TB. Binomial logistic regression was used for evaluating associations between polymorphisms and risk of contracting TB, an association between NRAMP1-D543N-A/A genotype distribution and TB susceptibility was found in Warao Amerindians. Regarding Venezuelan populations having different genetic backgrounds; statistically significant TB associations concerning NRAMP1-D543N-A/A, INT4-C/C and 3'UTR-TGTG+/+ variant genotype distributions in Warao Amerindians (indigenous) compared to Creole (admixed non-indigenous population) individuals were found. In conclusion, the results thus indicated that the association between NRAMP1-D543N-A/A genotype and TB in Warao Amerindians could support such allele's role in host susceptibility to Mtb infection.

Interleukin 4 gene polymorphisms and the risk of tuberculosis: A meta-analysis

BACKGROUND

Interleukin-4 (IL-4) is implicated in the progression of tuberculosis (TB); however, these results remain controversial.

OBJECTIVES

This meta-analysis examined the relationship between IL and 4 polymorphisms (-589C/T, +4221C > A, and -33C/T) and the risk of TB.

METHODS

A retrospective database analysis was conducted using the CNKI and PubMed databases. Using fixed- and random-effects models, we calculated the combined odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

We identified 14 articles related to this topic, and theresultsshowed that the IL-4 -589C/T polymorphism didnotinfluencethe risk of TB. However,in subgroupanalyses we found that the IL-4 -589C/T polymorphism was associated with the risk of TB inCaucasians (recessive modelOR = 2.54, 95% CI = 1.30-4.96). In our study, the IL-4--33C/T polymorphism was not associated with the risk of TB. The IL-4 + 4221C > A polymorphism was associated with the risk of TB (recessive model: OR = 1.40, 95% CI = 1.07-1.83).

CONCLUSION

This meta-analysis showed that the IL-4 -589C/T polymorphism was associated with TB risk in Caucasian populations, and the IL-4 + 4221C > A polymorphism is associated with TB risk.

Investigation on Probable Association Between IL-13, IL-13RA1, and IL-13RA2 Genes Polymorphism and Pulmonary Tuberculosis

Objective

Our study aimed to explore the association of IL-13, IL-13RA1, and IL-13RA2 genes polymorphisms with PTB susceptibility and its clinical features.

Methods

Nine SNPs were genotyped by improved multiple ligase detection reaction (iMLDR) in 476 PTB patients and 473 controls. The association between these SNPs and PTB risk was analyzed using SPSS software and haplotype analysis was assessed using SHEsis software.

Results

The IL-13RA1 rs2495636 GA genotype frequency in PTB patients was significantly decreased, and IL-13RA2 rs5946039 A allele was related to the lower risk of PTB. In IL-13 gene, rs20541 variant was found to be associated with PTB risk under recessive mode. Moreover, IL-13RA1 rs141573089 C allele was significantly lower in PTB presenting with fever, drug resistance, and CC genotype was decreased in PTB presenting with leukopenia. IL-13RA1 rs2495636 polymorphism was associated with drug resistance, pulmonary infection, and IL-13RA2 rs3795175, rs638376 polymorphisms were related to drug resistance in PTB patients.

Conclusion

IL-13 rs20541, IL-13RA1 rs2495636, IL-13RA2 rs5946039 polymorphisms might be contributed to the genetic background of PTB in Chinese population.

Association of IL-4 rs2243250 polymorphism with susceptibility to tuberculosis: A meta-analysis involving 6794 subjects

BACKGROUND

Interleukin-4 (lL-4) is a critical negative cytokine in tuberculosis (TB) immune process, acting through modulating macrophages activation and Th1/Th2 balance. rs2243250 has been demonstrated to be associated with enhanced promoter strength in IL-4 expression. We performed a meta-analysis to assess the association between IL-4 rs2243250 polymorphism and TB risk.

METHODS

We identified relevant studies by a comprehensive search of PubMed, Web of Science, and Embase databases, published up to February 10, 2021. The pooled odds ratios (ORs) and its 95% confidential intervals (95%CIs) were used to evaluate the associations under five genetic models. All statistical analyses were conducted with STATA 12.0 software.

RESULTS

Totally 11 qualified studies involving 3097 TB cases and 3697 controls were enrolled in this meta-analysis. Overall, we didn't detect any significant association between IL-4 rs2243250 polymorphism and TB risk (T vs. C: OR = 1.05, 95% CI = 0.85-1.30, p = 0; 65; TT + TC vs. CC: OR = 1.05, 95% CI = 0.73-1.50, p = 0.81; TT vs. TC + CC: OR = 1.10, 95% CI = 0.81-1.50, p = 0.54; TT vs. CC: OR = 1.17, 95% CI = 0.71-1.94, p = 0.54; TC vs. CC: OR = 1.03, 95% CI = 0.73-1.45, p = 0.88). Significant heterogeneity was identified in analyses under all genetic models. However, in the subgroup of European population, the recessive model provided an OR of 2.54 (1.30-4.96), with no significant between-study heterogeneity.

CONCLUSION

In conclusion, our meta-analysis indicated that IL-4 rs2243250 may increase TB risk in European population in recessive genetic model. Further research is needed to clarify the cause of ethnic difference in genetic association study.

Amerindian genetic ancestry as a risk factor for tuberculosis in an amazonian population

In recent years, the incidence of tuberculosis (TB) has declined worldwide, although this disease still occurs at relatively high rates in Amerindian populations. This suggests that the genetic ancestry of Amerindians may be an important factor in the development of infections, and may account for at least some of the variation in infection rates in the different populations. The present study investigated the potential influence of Amerindian genetic ancestry on susceptibility to tuberculosis in an Amazon population. The study included 280 patients diagnosed with tuberculosis and 138 asymptomatic hospital employees with no history of TB, but who were in contact with bacterially active TB patients. Ancestry analysis was run on a set of 61 Ancestry-Informative Markers to estimate European, African, and Amerindian genetic ancestry using STRUCTURE v2.2. The TB group had significantly higher Amerindian ancestry in comparison with the control group, and significantly lower European ancestry. Amerindian ancestry in the 20–60% range was found to be the principal risk factor for increased susceptibility to TB. The results of the study indicate that Amerindian ancestry is an important risk factor for susceptibility to TB in the admixed population of the Brazilian Amazon region.

[Tuberculosis in indigenous children and adolescents in Brazil: factors associated with death and treatment dropout]

The study aimed to describe clinical and sociodemographic characteristics, estimate incidence, and analyze factors associated with dropout and death during treatment of TB cases reported in indigenous children and adolescents in Brazil from 2006 to 2016. A historical case series was performed on incidence according to age bracket and major geographic region, and multinomial logistic regression was used to explain factors associated with treatment dropout and death. Of the 2,096 reported cases, 88.2% evolved to cure, 7.2% dropped out of treatment, and 4.6% evolved to death. There was a predominance of cases in boys 15-19 years of age and a higher proportion of deaths (55.7%) in children < 4 years. Considering indigenous children and adolescents with TB in Brazil as a whole, mean incidence was 49.1/100,000, ranging from 21.5/100,000 to 97.6/100,000 in the Northeast and Central, respectively. Cases with insufficient and irregular follow-up showed higher odds of dropout (OR = 11.1; 95%CI: 5.2-24.8/OR = 4.4; 95%CI: 1.9-10.3) and death (OR = 20.3; 95%CI: 4.9-84.9/OR = 5.1; 95%CI: 1.2-22.7). Cases in retreatment (OR = 2.4; 95%CI: 2.08-8.55) and with HIV coinfection (OR = 8.2; 95%CI: 2.2-30.9) were also associated with dropout. Extrapulmonary (OR = 1.8; 95%CI: 1.1-3.3) and mixed clinical forms (OR = 5.6; 95%CI: 2.8-11.4), age < 4 years (OR = 3.1; 95%CI: 1.5-6.4), and cases from the North (OR = 2.8; 95%CI: 1.1-7.1) and Central (OR = 2.8; 95%CI: 1.1-7.0) were associated with death. TB control in indigenous children and adolescents cannot be achieved without investments in research and development and without reducing social inequalities.

Polymorphisms of cytokine genes and tuberculosis in two independent studies

Cytokine gene single nucleotide polymorphisms (SNPs) can influence cytokine levels, which may be associated with tuberculosis (TB) susceptibility. There is evidence that interleukin 1B (IL1B), tumor necrosis factor-alpha (TNF-alpha), and IL6 may be involved in the progression of TB. Using a self-validating case-control design, we selected eleven functional SNPs in IL1B, TNF and IL6 to detect their association with TB in Chinese Han and Tibetan populations. The associations between SNPs and TB were estimated by computing the odds ratios (ORs) and 95% confidence intervals (95% CI) using logistic regression analyses. We found that the IL1B rs16944 polymorphism was associated with decreased risk of TB in the two studies. The G allele at rs2069837 of IL6 was significantly more common in controls than in TB patients in the Han population. Moreover, TNF rs1799964 and rs1800630 were risk factors for susceptibility to TB, which were validated in the Chinese Tibetan population. In addition, TNF rs1799724 and rs1800629 were associated with TB, but only in the Tibetan population. In conclusion, SNPs of the IL1B and TNF gene were associated with TB susceptibility in Chinese Han and Tibetan populations. IL6 polymorphism may be considered as a protective factor for TB in the Chinese Han population, but not the Tibetan population.

PPE17 (Rv1168c) protein of Mycobacterium tuberculosis detects individuals with latent TB infection

Latent tuberculosis infection (LTBI) is a clinically distinct category of Mycobacterium tuberculosis (Mtb) infection that needs to be diagnosed at the initial stage. We have reported earlier that one of the Mtb proline-proline-glutamic acid (PPE) proteins, PPE17 (Rv1168c) is associated with stronger B-cell and T-cell responses and could be used to diagnose different clinical categories of active TB patients with higher specificity and sensitivity than PPD and ESAT-6. Based on these observations we further tested the potential of PPE17 for the diagnosis of LTBI. We tested 198 sera samples collected from LTBI individuals (n = 61), QFT-negative (n = 58) and active TB patients (n = 79). Individuals were defined as LTBI by QuantiFERON-TB Gold In-Tube test (QFT–GIT) positive results, while active TB patients were confirmed based on the guidelines of the Revised National TB Control Programme of India. The antibody responses against PPE17, ESAT-6:CFP-10 and PPD were compared in these subjects by enzyme-linked immunosorbent assay. We observed that LTBI individuals show a higher sero-reactivity to PPE17 as compared to currently used latent TB diagnostic antigens like ESAT-6, CFP-10 and PPD. The LTBI and active TB patients display almost similar sensitivity. Interestingly, PPE17 could discriminate LTBI positive subjects from the QFT-negative subjects (P < 0.001). Our study hints that PPE17 may be used as a novel serodiagnostic marker to screen the latently infected subjects and may also be used as a complimentary tool to the QFT–GIT.

The N-terminal domain of Mycobacterium tuberculosis PPE17 (Rv1168c) protein plays a dominant role in inducing antibody responses in active TB patients

The PPE (proline-proline-glutamic acid) proteins of Mycobacterium tuberculosis are characterized by a conserved N-terminal domain of approximately 180 amino acids and variable C-terminal domain. Since last decade, these proteins have gained much importance in the serodiagnosis of tuberculosis (TB) as they act as a source of antigenic variation. We have demonstrated earlier that one of the PPE proteins PPE17 (Rv1168c) induces strong B-cell and T-cell responses in active TB disease and also displays a higher antibody titer compared to immunodominant antigens such as ESAT-6, Hsp60 and PPD. However, the immunodominant domain of PPE17 (N-terminal or C-terminal) was not examined in detail. In the present study, we observed that antibody responses elicited in TB patients were directed mostly towards the N-terminal domain of PPE17 (N-PPE17). The antibody generated against N-PPE17 in TB patients did not significantly cross-react with N-terminal domains of other PPE proteins used in this study. Our data suggest that the N-terminal domain of PPE17 protein is immunodominant and could be used as a better serodiagnostic marker than the full-length PPE17 protein.

Prevalence and factors associated with latent tuberculosis infection in an indigenous population in the Brazilian Amazon

INTRODUCTION

Recent studies have shown a high incidence and prevalence of latent tuberculosis infection (LTBI) in indigenous populations around the World. We aimed to estimate the prevalence and annual risk of infection (ARI) as well as to identify factors associated with LTBI in an indigenous population from the Brazilian Amazon.

METHODS

We conducted a cross-sectional study in 2011. We performed tuberculin skin tests (TSTs), smears and cultures of sputum samples, and chest radiographs for individuals who reported cough for two or more weeks. Associations between LTBI (TST ≥5mm) and socio-demographic, clinical, and epidemiological characteristics were investigated using Poisson regression with robust variance. Prevalence ratio (PR) was used as the measure of association.

RESULTS

We examined 263 individuals. The prevalence of LTBI was 40.3%, and the ARI was 2.4%. Age ≥15 years [PR=5.5; 95% confidence interval (CI): 3.5-8.6], contact with tuberculosis (TB) patients (PR=3.8; 95% CI: 1.2-11.9), previous TB history (PR=1.4; 95% CI: 1.2-1.7), and presence of Bacillus Calmette-Guérin (BCG) scar (PR=1.9, 95% CI: 1.2-2.9) were associated with LTBI.

CONCLUSIONS

Although some adults may have been infected years prior, the high prevalence of infection and its strong association with age ≥15 years, history of TB, and recent contact with TB patients suggest that the TB transmission risk is high in the study area.

Ethnic and Racial Inequalities in Notified Cases of Tuberculosis in Brazil

OBJECTIVE

This study analysed clinical and sociodemographic aspects and follow-up for notified cases of tuberculosis (TB) and explored inequalities in incidence rates and outcome by colour or race and the geographic macro-regions of Brazil.

METHODS

This paper reports the results of a population-based descriptive epidemiological study of all notified cases of TB in Brazil during the period from 01/01/2008 to 31/12/2011. We analysed sociodemographic and clinical variables according to colour or race (white, black, Asian, mixed, and indigenous) and geographic macro-regions of the country (North, Northeast, Central-West, South, and Southeast).

RESULTS

During the study period, the average incidence of TB in Brazil was 36.7 cases per 100,000 inhabitants, with the highest rates occurring in the North and Southeast regions. The analysis of TB notifications by colour or race revealed that the indigenous population presented the highest incidence rates in all macro-regions except the South, where higher rates were reported in black patients. 'Cured' was the most frequently reported treatment outcome for all skin colour categories. The highest cure rate occurred among the indigenous population (76.8%), while the lowest cure rate occurred among the black population (70.7%). Rates of treatment default were highest among blacks (10.5%) and lowest among the indigenous population (6.9%). However, the fatality rate was similar across race categories, varying between 2.8% and 3.8% for whites and the indigenous population, respectively. The lowest cure rates were observed when follow-up was inadequate (58.3%), and the highest was observed when the follow-up was classified as excellent (96.8%).

CONCLUSIONS

This study revealed that-apart from the heterogeneous distribution of TB among the Brazilian macro-regions-ethnic-racial inequalities exist in terms of clinical-epidemiological characteristics and incidence rates as well as follow-up for cases undergoing treatment. The highest rates of TB occurred among the indigenous people.

Role of mitochondrial oxidative stress on lymphocyte homeostasis in patients diagnosed with extra-pulmonary tuberculosis

Extra-pulmonary tuberculosis is often an underrated illness. Recent clinical studies have pointed out that lymphocyte homeostasis is dramatically disturbed as revealed through a series of signs and symptoms. Lymphocytes, the known effector cells of our immune system, play an important role in providing immunologic resistance against Mycobacterium infection. It is important to have quantitative insights into the lifespan of these cells; therefore, we aimed to study the precise effect of gastrointestinal tuberculosis infection on peripheral blood lymphocyte subpopulations and function. Our results indicated that gastrointestinal tuberculosis could increase mitochondrial oxidative stress, lower mitochondrial DNA copy number, promote nuclear DNA damage and repair response, decrease mitochondrial respiratory chain enzyme activities, and upregulate Bcl-2 and caspase-3 gene expression in lymphocytes. We further revealed that Mycobacterium infection induces autophagy for selective sequestration and subsequent degradation of the dysfunctional mitochondrion before activating cellular apoptosis in the peripheral lymphocyte pool. Together, these observations uncover a new role of mitochondrial-nuclear crosstalk that apparently contributes to lymphocyte homeostasis in gastrointestinal tuberculosis infection.

Chronic symptoms and pulmonary dysfunction in post-tuberculosis Brazilian patients

Background

Questionnaire and spirometry were applied to post-tuberculosis indigenous and non-indigenous individuals from Dourados, Brazil, to investigate the prevalence of chronic respiratory symptoms and pulmonary dysfunction.

Methods

This was a cross-sectional study in cured tuberculosis individuals as reported in the National System on Reportable Diseases (SINAN) from 2002 to 2012.

Results

One hundred and twenty individuals were included in the study and the prevalence of chronic respiratory symptoms was 45% (95% CI, 34–59%). Respiratory symptoms included cough (28%), sputum (23%), wheezing (22%) and dyspnea (8%). These symptoms were associated with alcoholism, AOR: 3.1 (1.2–8.4); less than 4 years of schooling, AOR: 5.0 (1.4–17.7); and previous pulmonary diseases, AOR: 5.4 (1.7–17.3). Forty-one percent (95% CI, 29–56) had pulmonary disorders, of which the most prevalent were obstructive disorders (49%), followed by obstructive disorder with reduced forced vital capacity disorders (46%) and restrictive disorders (5%). The lifestyle difference could not explain differences in chronic symptoms and/or the prevalence of pulmonary dysfunction.

Conclusion

The high prevalence of chronic respiratory symptoms and pulmonary dysfunction in post-tuberculosis patients indicates a need for further interventions to reduce social vulnerability of patients successfully treated for tuberculosis.

Serum Th17 cytokines in leprosy: correlation with circulating CD4(+) CD25 (high)FoxP3 (+) T-regs cells, as well as down regulatory cytokines

Leprosy is not only a bacteriological disease but also an immunological disease, in which T helper17 and CD4(+) CD25(high)FoxP3(+) regulatory T cells (T-regs), among others, may play a role. We aimed to evaluate serum levels of interleukin (IL)-17, IL-22 (Th17 cytokines), IL-10 and transforming growth factor (TGF)-β (down regulatory cytokines) in 43 untreated leprosy patients and 40 controls by enzyme-linked immunosorbent assay, and to assess circulating CD4(+) CD25(high)FoxP3(+)T-regs in patients using flow cytometry. Patients were grouped into tuberculoid, pure neural, borderline, lepromatous, type 1 reactional leprosy, and erythema nodosum leprosum. IL-10 and TGF-β were significantly higher in patients as compared to controls (p < 0.001), while IL-17, but not IL-22, was significantly lower (p < 0.001), with no significant difference comparing patients' subgroups. Significantly higher CD4(+) CD25(high)FoxP3(+)T-regs levels was detected in tuberculoid, type 1 reaction and pure neural leprosy, while the lowest levels in erythema nodosum leprosum (p < 0.001). TregsFoxP3 expression% was significantly lower in pure neural leprosy than other patients' subgroups (p < 0.05). T-regs/T-effs was lowest in erythema nodosum leprosum (p < 0.05). TGF-β correlated negatively with TregsFoxP3 expression% and T-effs% (p = 0.009 and 0.018 respectively). Leprosy is associated with defective IL-17 and overproduction of IL-10 and TGF-β. Tuberculoid, type 1 reaction and pure neural leprosy express significantly higher circulating T-regs, consistent with effector immune mechanisms activation, but with lower TregsFoxP3 expression (in pure neural leprosy). Erythema nodosum leprosum is characterized by deficient T-regs and increased TregsFoxP3 expression%. The present study pinpointed a potential role of Th17, CD4(+) CD25(high)FoxP3(+)T-regs, and probably CD4(+) CD25(+)IL-10(+) T regulatory cells 1 (Tr1), and Th3 in leprosy.

Polymorphisms in the interleukin 18 receptor 1 gene and tuberculosis susceptibility among Chinese

Tuberculosis (TB), an infectious disease caused by infection of Mycobacterium tuberculosis, is a major public health challenge globally. Genetic epidemiological evidence suggests a genetic basis for TB, but the molecular mechanism for a genetic predisposition to TB remains largely unknown. Thirty-five tag single-nucleotide polymorphisms (SNPs) across 11 candidate cytokines and related genes, including IL-12/IFN-γ axis genes (IL12B, IL12RB1, IL18R1, IL27, IFNGR1, IFNGR2 and STAT1), the TNF gene locus (TNF and LTA), IL10, and CCL2, were genotyped using Sequenom's iPLEX assays in 1,032 patients with TB and 1,008 controls of Chinese Han origin. We did not find that any of the 35 tag SNPs individually or as haplotypes was significantly associated with susceptibility to TB, on the basis of multivariable logistic regression analysis with adjustment for age and sex. However, stratification analyses showed that, in those with age 46 years or older, carrying the rs1974675 T allele in the IL18R1 gene had a significantly decreased susceptibility to TB occurrence compared with carrying the C/C genotype (OR = 0.57, P = 5.0×10(-4)). Further analysis indicated that a SNP in absolute linkage disequilibrium with rs1974675, rs3755276, is located within a CpG dinucleotide and showed hypomethylation in controls than in patients (19.6% vs. 31.4%; P = 1.0×10(-4)) and genotype-specific DNA methylation at the IL18R1 promoter and IL18R1 mRNA levels. In addition, DNA methylation levels were significantly inversely correlated with mRNA levels. Thus, decreased mRNA levels of IL18R1 due to rs3755276 may partially mediate the increased susceptibility to TB risk.

[Social inequalities and tuberculosis: an analysis by race/color in Mato Grosso do Sul, Brazil]

OBJECTIVE

To describe the sociodemographic and clinical-epidemiological characteristics of tuberculosis cases and identify associated factors with abandoning treatment and death whilst undergoing treatment.

METHODS

Epidemiological study based on cases of tuberculosis recorded in indigenous and non-indigenous individuals according to race/color in Mato Grosso do Sul, Midwestern Brazil, between 2001 and 2009. Descriptive analysis of the cases was carried out according to the variables of sex, age group, residence, type of test used in the diagnosis, clinical form, supervised treatment and final status, according to race/color. Univariate/multivariate logistic regression analyses were used to identify predictors of abandoning treatment and death, using odds ratio as a measure of association. A time series of incidence according to race/color was constructed.

RESULTS

In the period, 6,962 new cases of tuberculosis were registered, 15.6% being among indigenous. The illness was predominantly found in men and adults (20-44 years old) in all groups. Most of the indigenous patients lived in rural areas (79.8%) and 13.5% of the records in indigenous occurred in children aged < 10 years. The average incidence in the state was 34.5/100,000 inhabitants, being 209.0, 73.1, 52.7, 23.0 and 22.4 in indigenous, and those with yellow, black, white and brown skin, respectively. Patients aged 20 to 44 years (OR = 13.3, 95%CI 1.9;96.8), male (OR = 1.6, 95%CI 1.1;2.3) and of black race/color (OR = 2.5, 95%CI 1.0;6.3) were associated with abandoning treatment, while patients aged > 45 years (OR = 3.0, 95%CI 1.2;7.8) and with the mixed form (OR = 2.3, 95%CI 1.1;5.0) showed association with death. Although they only account for 3.0% of the population, the indigenous were responsible for 15.6% of cases recorded during the period.

CONCLUSIONS

Major inequalities in the tuberculosis illness process were found between the categories studied. Incidence in the indigenous population was consistently higher than recorded in any other group, reaching more than six times the national average. It was among those with black and brown skin that the worst treatment results were observed, as they were twice as likely to abandon treatment as the indigenous. Poor program performance was strongly associated with abandoning treatment and death. It is thought that as long as there is no reduction in poverty inequalities in health indicators will remain.