Tuberculosis treatment loss to follow-up in children exposed at home: A prospective cohort study.

Background: Loss to follow-up (LTFU) from tuberculosis (TB) treatment and care is a significant public health problem. It is important to understand what drives LTFU in children - a population whose treatment and management depend on an adult caregiver - to better provide support services to families affected by TB. Methods: We conducted a prospective cohort study of household contacts in Lima, Peru (2009-12). Using multilevel logistic regression analysis, we explored individual-level characteristics of children and their adult household members with TB disease to identify risk factors for LTFU among children initiated on treatment for TB. Results: A total of 154 child (0-14 years) household contacts were diagnosed with TB and initiated on treatment. While most (n = 133, 86.4%) had a successful outcome, 20 (13.0%) children were LTFU. Six (30.0%) children were LTFU within three months, nine (45.0%) between five to seven months, and three (15.0%) after seven months of treatment being initiated. In univariable analysis, children with index patients above 25 years of age had decreased odds of being LTFU (odds ratio = 0.26; 95% confidence interval = 0.08-0.84) compared to children with index patients 25 years or younger. Conclusions: In this cohort, more than 10% of children sick with TB who were exposed to the disease at home were LTFU. An integrated, family-centred TB prevention and management approach may reduce barriers to a child completing their course of TB treatment.

History of tuberculosis disease is associated with genetic regulatory variation in Peruvians.

A quarter of humanity is estimated to have been exposed to Mycobacterium tuberculosis (Mtb) with a 5-10% risk of developing tuberculosis (TB) disease. Variability in responses to Mtb infection could be due to host or pathogen heterogeneity. Here, we focused on host genetic variation in a Peruvian population and its associations with gene regulation in monocyte-derived macrophages and dendritic cells (DCs). We recruited former household contacts of TB patients who previously progressed to TB (cases, n = 63) or did not progress to TB (controls, n = 63). Transcriptomic profiling of monocyte-derived DCs and macrophages measured the impact of genetic variants on gene expression by identifying expression quantitative trait loci (eQTL). We identified 330 and 257 eQTL genes in DCs and macrophages (False Discovery Rate (FDR) < 0.05), respectively. Four genes in DCs showed interaction between eQTL variants and TB progression status. The top eQTL interaction for a protein-coding gene was with FAH, the gene encoding fumarylacetoacetate hydrolase, which mediates the last step in mammalian tyrosine catabolism. FAH expression was associated with genetic regulatory variation in cases but not controls. Using public transcriptomic and epigenomic data of Mtb-infected monocyte-derived dendritic cells, we found that Mtb infection results in FAH downregulation and DNA methylation changes in the locus. Overall, this study demonstrates effects of genetic variation on gene expression levels that are dependent on history of infectious disease and highlights a candidate pathogenic mechanism through pathogen-response genes. Furthermore, our results point to tyrosine metabolism and related candidate TB progression pathways for further investigation.

Chest Radiograph Screening for Detecting Subclinical Tuberculosis in Asymptomatic Household Contacts, Peru.

The World Health Organization's end TB strategy promotes the use of symptom and chest radiograph screening for tuberculosis (TB) disease. However, asymptomatic early states of TB beyond latent TB infection and active disease can go unrecognized using current screening criteria. We conducted a longitudinal cohort study enrolling household contacts initially free of TB disease and followed them for the occurrence of incident TB over 1 year. Among 1,747 screened contacts, 27 (52%) of the 52 persons in whom TB subsequently developed during follow-up had a baseline abnormal radiograph. Of contacts without TB symptoms, persons with an abnormal radiograph were at higher risk for subsequent TB than persons with an unremarkable radiograph (adjusted hazard ratio 15.62 [95% CI 7.74-31.54]). In young adults, we found a strong linear relationship between radiograph severity and time to TB diagnosis. Our findings suggest chest radiograph screening can extend to detecting early TB states, thereby enabling timely intervention.

Who Transmits Tuberculosis to Whom: A Cross-Sectional Analysis of a Cohort Study in Lima, Peru.

Rationale: The persistent burden of tuberculosis (TB) disease emphasizes the need to identify individuals with TB for treatment and those at a high risk of incident TB for prevention. Targeting interventions toward those at high risk of developing and transmitting TB is a public health priority. Objectives: We aimed to identify characteristics of individuals involved in TB transmission in a community setting, which may guide the prioritization of targeted interventions. Methods: We collected clinical and sociodemographic data from a cohort of patients with TB in Lima, Peru. We used whole-genome sequencing data to assess the genetic distance between all possible pairs of patients; we considered pairs to be the result of a direct transmission event if they differed by three or fewer SNPs, and we assumed that the first diagnosed patient in a pair was the transmitter and the second was the recipient. We used logistic regression to examine the association between host factors and the likelihood of direct TB transmission. Measurements and Main Results: Analyzing data from 2,518 index patients with TB, we identified 1,447 direct transmission pairs. Regardless of recipient attributes, individuals less than 34 years old, males, and those with a history of incarceration had a higher likelihood of being transmitters in direct transmission pairs. Direct transmission was more likely when both patients were drinkers or smokers. Conclusions: This study identifies men, young adults, former prisoners, alcohol consumers, and smokers as priority groups for targeted interventions. Innovative strategies are needed to extend TB screening to social groups such as young adults and prisoners with limited access to routine preventive care.

Subjective socioeconomic status: an alternative to objective socioeconomic status.

BACKGROUND: Subjective "ladder" measurements of socio-economic status (SES) are easy-to-administer tools that ask respondents to rate their own SES, allowing them to evaluate their own material resources and determine where it places them relative to their community. Here, we sought to compare the MacArthur Scale of Subjective Social status to the WAMI, an objective measure of SES that includes data on water and sanitation, asset ownership, education, and income. METHODS: Leveraging a study of 595 tuberculosis patients in Lima, Peru, we compared the MacArthur ladder score to the WAMI score using weighted Kappa scores and Spearman's rank correlation coefficient. We identified outliers that fell outside the 95th percentile and assessed the durability of the inconsistencies between scores by re-testing a subset of participants. We then used Akaike information criterion (AIC) to compare the predictability of logistic regression models evaluating the association between the two SES scoring systems and history of asthma. RESULTS: The correlation coefficient between the MacArthur ladder and WAMI scores was 0.37 and the weighted Kappa was 0.26. The correlation coefficients differed by less than 0.04 and the Kappa ranged from 0.26 to 0.34, indicating fair agreement. When we replaced the initial MacArthur ladder scores with retest scores, the number of individuals with disagreements between the two scores decreased from 21 to 10 and the correlation coefficient and weighted Kappa both increased by at least 0.03. Lastly, we found that when we categorized WAMI and MacArthur ladder scores into three groups, both had a linear trend association with history of asthma with effect sizes and AICs that differed by less than 15% and 2 points, respectively. CONCLUSION: Our findings demonstrated fair agreement between the MacArthur ladder and WAMI scores. The agreement between the two SES measurements increased when they were further categorized into 3-5 categories, the form in which SES is often used in epidemiologic studies. The MacArthur score also performed similarly to WAMI in predicting a socio-economically sensitive health outcome. Researchers should consider subjective SES tools as an alternative method for measuring SES, particularly in large health studies where data collection is a burden.

Spatial scale of tuberculosis transmission in Lima, Peru.

Spatially targeted interventions may be effective alternatives to individual or population-based prevention strategies against tuberculosis (TB). However, their efficacy may depend on the mechanisms that lead to geographically constrained hotspots. Local TB incidence may reflect high levels of local transmission; conversely, they may point to frequent travel of community members to high-risk areas. We used whole-genome sequencing to explore patterns of TB incidence and transmission in Lima, Peru. Between 2009 and 2012, we recruited incident pulmonary TB patients and their household contacts, whom we followed for the occurrence of TB disease. We used whole-genome sequences of 2,712 Mycobacterial tuberculosis isolates from 2,440 patients to estimate pariwise genomic distances and compared these to the spatial distance between patients' residences. Genomic distances increased rapidly as spatial distances increased and remained high beyond 2 km of separation. Next, we divided the study catchment area into 1 × 1 km grid-cell surface units and used household spatial coordinates to locate each TB patient to a specific cell. We estimated cell-specific transmission by calculating the proportion of patients in each cell with a pairwise genomic distance of 10 or fewer single-nucleotide polymorphisms. We found that cell-specific TB incidence and local transmission varied widely but that cell-specific TB incidence did not correlate closely with our estimates of local transmission (Cohen's k = 0.27). These findings indicate that an understanding of the spatial heterogeneity in the relative proportion of TB due to local transmission may help guide the implementation of spatially targeted interventions.

Multimodally profiling memory T cells from a tuberculosis cohort identifies cell state associations with demographics, environment and disease.

Multimodal T cell profiling can enable more precise characterization of elusive cell states underlying disease. Here, we integrated single-cell RNA and surface protein data from 500,089 memory T cells to define 31 cell states from 259 individuals in a Peruvian tuberculosis (TB) progression cohort. At immune steady state >4 years after infection and disease resolution, we found that, after accounting for significant effects of age, sex, season and genetic ancestry on T cell composition, a polyfunctional type 17 helper T (TH17) cell-like effector state was reduced in abundance and function in individuals who previously progressed from Mycobacterium tuberculosis (M.tb) infection to active TB disease. These cells are capable of responding to M.tb peptides. Deconvoluting this state-uniquely identifiable with multimodal analysis-from public data demonstrated that its depletion may precede and persist beyond active disease. Our study demonstrates the power of integrative multimodal single-cell profiling to define cell states relevant to disease and other traits.

Dysglycemia is associated with Mycobacterium tuberculosis lineages in tuberculosis patients of North Lima-Peru.

This study was performed to investigate the role of dysglycemia on the genetic diversity of Mycobacterium tuberculosis (MTB) among pulmonary tuberculosis (TB) patients to build scientific evidence about the possible mechanisms of TB transmission. MTB isolates obtained of patients affected by pulmonary tuberculosis from health care facilities of North Lima-Peru, were analyzed using whole genome sequencing and 24-locus mycobacterial interspersed repetitive-unit -variable-number tandem repeats (MIRU-VNTR). Subsequently, clinical and epidemiological characteristics were associated with clustering, lineages and comorbid conditions. The analysis carried out 112 pulmonary TB patients from various health centers in North Lima, 17 (15%) had diabetes mellitus (DM) and 33 (29%) had pre-diabetes (PDM). Latin American-Mediterranean, Haarlem and Beijing were the most frequent MTB lineages found in those patients. Previous TB (adjusted odds ratio [aOR] = 3.65; 95%CI: 1.32-17.81), age (aOR = 1.12; 95%CI: 1.03-1.45) and Beijing lineage (aOR = 3.53; 95%CI: 1.08-13.2) were associated with TB-DM comorbidity. Alcoholism (aOR = 2.92; 95%CI: 1.10-8.28), age (aOR = 1.05; 95%CI: 1.03-1.12) and Haarlem lineage (aOR = 2.54; 95%CI: 1.04-6.51) were associated with TB-PDM comorbidity. Beijing and Haarlem lineages were independently associated with TB-DM and TB-PDM comorbidities, respectively. Although these findings may be surprising, we must be cautious to suggest that dysglycemia could be associated with a highly clustering and predisposition of MTB lineages related to a serious impact on the severity of TB disease, which requires further research.

Tuberculosis clinical presentation and treatment outcomes in pregnancy: a prospective cohort study.

BACKGROUND: There is limited research to guide TB treatment specifically in pregnant women and few studies have described the presentation of TB in pregnant women. We aimed to understand TB presentation and treatment outcomes in pregnant women in a low HIV burden setting. We describe a cohort of women of childbearing age treated for TB disease in Lima, Peru, and compare clinical presentation and treatment outcomes among pregnant and non-pregnant women between 2009 and 2012, including 36 pregnant women. METHODS: This is a prospective cohort study. Subjects were recruited from across 106 public health centers in Lima, Peru. Baseline demographic, medical history, and drug-susceptibility test results were collected. We used descriptive statistics to describe demographic and clinical characteristics of the women using Pearson chi-squared, Fisher's exact tests, or Kruskal-Wallis. RESULTS: Among 4500 individuals with pulmonary TB disease, 1334 women were included in analysis with 36 (2.69%) pregnant women. Pregnant women had similar demographics, past medical histories, and clinical presentation to non-pregnant women, except being more likely to be married (p = 0.01) and have cardiac disease (p = 0.04) and less likely to have weight loss (p = 0.05). Twenty (71.4%) pregnant women had pan-susceptible TB compared with 616 (63.1%) non-pregnant women; four (14.3%) pregnant women had mono-resistant TB compared with 154 (15.8%) non-pregnant women; and four (14.3%) pregnant women had multi-drug-resistant TB compared with 140 (14.3%) of non-pregnant women (p = 0.53). Twenty-eight (96.6%) pregnant women had a successful outcome (cure, completed treatment, treatment ended early by clinical team) while one (3.4%) had an unsuccessful outcome (treatment failed) and 1074 (97.3%) non-pregnant women had a successful outcome while 30 (2.7%) had an unsuccessful outcome (p = 0.56). CONCLUSION: In this cohort with low HIV co-infection, we found high TB treatment success rates in both pregnant and non-pregnant women, irrespective of drug-susceptibility profiles. If treated appropriately, pregnant women with TB disease can have successful outcomes.

Isoniazid Preventive Therapy in Contacts of Multidrug-Resistant Tuberculosis.

Rationale: The World Health Organization recommends the use of isoniazid (INH) alone or in combination with rifapentine to treat latent tuberculosis infections. The recent rise of drug-resistant tuberculosis has complicated the choice of treatment regimen for latent tuberculosis infection.Objectives: To evaluate the effects of INH preventive therapy on the contacts of patients with multidrug-resistant tuberculosis.Methods: In a prospective cohort study conducted between September 2009 and August 2012, we identified 4,500 index patients with tuberculosis and 14,044 tuberculosis-exposed household contacts who we followed for 1 year for the occurrence of incident tuberculosis disease. Although Peruvian national guidelines specify that INH preventive therapy should be provided to contacts aged 19 years old or younger, only half this group received INH preventive therapy.Measurements and Main Results: Among 4,216 contacts under 19 years of age, 2,106 contacts (50%) initiated INH preventive therapy at enrollment. The protective effect of INH was more extreme in contacts exposed to drug-sensitive tuberculosis (adjusted hazard ratio, 0.30; 95% confidence interval, 0.18-0.48) and to multidrug-resistant tuberculosis (adjusted hazard ratio, 0.19; 95% confidence interval, 0.05-0.66) compared with those exposed to mono-INH-resistant tuberculosis (adjusted hazard ratio, 0.80; 95% confidence interval, 0.23-2.80). In the second independent study, tuberculosis occurred in none of the 76 household contacts who received INH preventive therapy compared with 3% (8 of 273) of those who did not.Conclusions: Household contacts who received INH preventive therapy had a lower incidence of tuberculosis disease even when they had been exposed to an index patient with multidrug-resistant tuberculosis. INH may have a role in the management of latent multidrug-resistant tuberculosis infection.

Mycobacterium tuberculosis Beijing Lineage and Risk for Tuberculosis in Child Household Contacts, Peru.

Few studies have prospectively compared the relative transmissibility and propensity to cause disease of Mycobacterium tuberculosis Beijing strains with other human-adapted strains of the M. tuberculosis complex. We assessed the effect of Beijing strains on the risk for M. tuberculosis infection and disease progression in 9,151 household contacts of 2,223 culture-positive pulmonary tuberculosis (TB) patients in Lima, Peru. Child contacts exposed to Beijing strains were more likely than child contacts exposed to non-Beijing strains to be infected at baseline, by 12 months of follow-up, and during follow-up. We noted an increased but nonsignificant tendency for child contacts to develop TB. Beijing strains were not associated with TB in adult contacts. These findings suggest that Beijing strains are more transmissible in children than are non-Beijing strains.

Two Clinical Prediction Tools to Improve Tuberculosis Contact Investigation.

BACKGROUND: Efficient contact investigation strategies are needed for the early diagnosis of tuberculosis (TB) disease and treatment of latent TB infections. METHODS: Between September 2009 and August 2012, we conducted a prospective cohort study in Lima, Peru, in which we enrolled and followed 14 044 household contacts of adults with pulmonary TB. We used information from a subset of this cohort to derive 2 clinical prediction tools that identify contacts of TB patients at elevated risk of progressing to active disease by training multivariable models that predict (1) coprevalent TB among all household contacts and (2) 1-year incident TB among adult contacts. We validated the models in a geographically distinct subcohort and compared the relative utilities of clinical decisions based on these tools to existing strategies. RESULTS: In our cohort, 296 (2.1%) household contacts had coprevalent TB and 145 (1.9%) adult contacts developed incident TB within 1 year of index patient diagnosis. We predicted coprevalent disease using information that could be readily obtained at the time an index patient was diagnosed and predicted 1-year incident TB by including additional contact-specific characteristics. The area under the receiver operating characteristic curves for coprevalent TB and incident TB were 0.86 (95% confidence interval [CI], .83-.89]) and 0.72 (95% CI, .67-.77), respectively. These clinical tools give 5%-10% higher relative utilities than existing methods. CONCLUSIONS: We present 2 tools that identify household contacts at high risk for TB disease based on reportable information from patient and contacts alone. The performance of these tools is comparable to biomarkers that are both more costly and less feasible than this approach.

Transmissibility and potential for disease progression of drug resistant Mycobacterium tuberculosis: prospective cohort study.

OBJECTIVE: To measure the association between phenotypic drug resistance and the risk of tuberculosis infection and disease among household contacts of patients with pulmonary tuberculosis. SETTING: 106 district health centers in Lima, Peru between September 2009 and September 2012. DESIGN: Prospective cohort study. PARTICIPANTS: 10 160 household contacts of 3339 index patients with tuberculosis were classified on the basis of the drug resistance profile of the patient: 6189 were exposed to drug susceptible strains of Mycobacterium tuberculosis, 1659 to strains resistant to isoniazid or rifampicin, and 1541 to strains that were multidrug resistant (resistant to isoniazid and rifampicin). MAIN OUTCOME MEASURES: Tuberculosis infection (positive tuberculin skin test) and the incidence of active disease (diagnosed by positive sputum smear or chest radiograph) after 12 months of follow-up. RESULTS: Household contacts exposed to patients with multidrug resistant tuberculosis had an 8% (95% confidence interval 4% to 13%) higher risk of infection by the end of follow-up compared with household contacts of patients with drug sensitive tuberculosis. The relative hazard of incident tuberculosis disease did not differ among household contacts exposed to multidrug resistant tuberculosis and those exposed to drug sensitive tuberculosis (adjusted hazard ratio 1.28, 95% confidence interval 0.9 to 1.83). CONCLUSION: Household contacts of patients with multidrug resistant tuberculosis were at higher risk of tuberculosis infection than contacts exposed to drug sensitive tuberculosis. The risk of developing tuberculosis disease did not differ among contacts in both groups. The evidence invites guideline producers to take action by targeting drug resistant and drug sensitive tuberculosis, such as early detection and effective treatment of infection and disease. TRIAL REGISTRATION: ClinicalTrials.gov NCT00676754.

Vitamin D status and risk of incident tuberculosis disease: A nested case-control study, systematic review, and individual-participant data meta-analysis.

BACKGROUND: Few studies have evaluated the association between preexisting vitamin D deficiency and incident tuberculosis (TB). We assessed the impact of baseline vitamins D levels on TB disease risk. METHODS AND FINDINGS: We assessed the association between baseline vitamin D and incident TB in a prospective cohort of 6,751 HIV-negative household contacts of TB patients enrolled between September 1, 2009, and August 29, 2012, in Lima, Peru. We screened for TB disease at 2, 6, and 12 months after enrollment. We defined cases as household contacts who developed TB disease at least 15 days after enrollment of the index patient. For each case, we randomly selected four controls from among contacts who did not develop TB disease, matching on gender and year of age. We also conducted a one-stage individual-participant data (IPD) meta-analysis searching PubMed and Embase to identify prospective studies of vitamin D and TB disease until June 8, 2019. We included studies that assessed vitamin D before TB diagnosis. In the primary analysis, we defined vitamin D deficiency as 25-(OH)D < 50 nmol/L, insufficiency as 50-75 nmol/L, and sufficiency as >75nmol/L. We estimated the association between baseline vitamin D status and incident TB using conditional logistic regression in the Lima cohort and generalized linear mixed models in the meta-analysis. We further defined severe vitamin D deficiency as 25-(OH)D < 25 nmol/L and performed stratified analyses by HIV status in the IPD meta-analysis. In the Lima cohort, we analyzed 180 cases and 709 matched controls. The adjusted odds ratio (aOR) for TB risk among participants with baseline vitamin D deficiency compared to sufficient vitamin D was 1.63 (95% CI 0.75-3.52; p = 0.22). We included seven published studies in the meta-analysis and analyzed 3,544 participants. In the pooled analysis, the aOR was 1.48 (95% CI 1.04-2.10; p = 0.03). The aOR for severe vitamin D deficiency was 2.05 (95% CI 0.87-4.87; p trend for decreasing 25-(OH)D levels from sufficient vitamin D to severe deficiency = 0.02). Among 1,576 HIV-positive patients, vitamin D deficiency conferred a 2-fold (aOR 2.18, 95% CI 1.22-3.90; p = 0.01) increased risk of TB, and the aOR for severe vitamin D deficiency compared to sufficient vitamin D was 4.28 (95% CI 0.85-21.45; p = 0.08). Our Lima cohort study is limited by the short duration of follow-up, and the IPD meta-analysis is limited by the number of possible confounding covariates available across all studies. CONCLUSION: Our findings suggest vitamin D predicts TB disease risk in a dose-dependent manner and that the risk of TB disease is highest among HIV-positive individuals with severe vitamin D deficiency. Randomized control trials are needed to evaluate the possible role of vitamin D supplementation on reducing TB disease risk.

Biological roles of filamin a in prostate cancer cells

ABSTRACT Objective This study aims to investigate the association of filamin A with the function and morphology of prostate cancer (PCa) cells, and explore the role of filamin A in the development of PCa, in order to analyze its significance in the evolvement of PCa. Materials and Methods A stably transfected cell line, in which filamin A expression was suppressed by RNA interference, was first established. Then, the effects of the suppression of filamin A gene expression on the biological characteristics of human PCa LNCaP cells were observed through cell morphology, in vitro cell growth curve, soft agar cloning assay, and scratch test. Results A cell line model with a low expression of filamin A was successfully constructed on the basis of LNCaP cells. The morphology of cells transfected with plasmid pSilencer-filamin A was the following: Cells were loosely arranged, had less connection with each other, had fewer tentacles, and presented a fibrous look. The growth rate of LNCap cells was faster than cells transfected with plasmid pSilencer-filamin A (P <0.05). The clones of LNCap cells in the soft agar cloning assay was significantly fewer than that of cells stably transfected with plasmid pSilencer-filamin A (P <0.05). Cells stably transfected with plasmid pSilencer-filamin A presented with a stronger healing and migration ability compared to LNCap cells (healing rate was 32.2% and 12.1%, respectively; P <0.05). Conclusion The expression of the filamin A gene inhibited the malignant development of LNCap cells. Therefore, the filamin A gene may be a tumor suppressor gene.

Biological roles of filamin a in prostate cancer cells.

OBJECTIVE: This study aims to investigate the association of filamin A with the function and morphology of prostate cancer (PCa) cells, and explore the role of filamin A in the development of PCa, in order to analyze its significance in the evolvement of PCa. MATERIALS AND METHODS: A stably transfected cell line, in which filamin A expression was suppressed by RNA interference, was first established. Then, the effects of the suppression of filamin A gene expression on the biological characteristics of human PCa LNCaP cells were observed through cell morphology, in vitro cell growth curve, soft agar cloning assay, and scratch test. RESULTS: A cell line model with a low expression of filamin A was successfully constructed on the basis of LNCaP cells. The morphology of cells transfected with plasmid pSilencer-filamin A was the following: Cells were loosely arranged, had less connection with each other, had fewer tentacles, and presented a fibrous look. The growth rate of LNCap cells was faster than cells transfected with plasmid pSilencer-filamin A (P<0.05). The clones of LNCap cells in the soft agar cloning assay was significantly fewer than that of cells stably transfected with plasmid pSilencer-filamin A (P<0.05). Cells stably transfected with plasmid pSilencer-filamin A presented with a stronger healing and migration ability compared to LNCap cells (healing rate was 32.2% and 12.1%, respectively; P<0.05). CONCLUSION: The expression of the filamin A gene inhibited the malignant development of LNCap cells. Therefore, the filamin A gene may be a tumor suppressor gene.

Vitamin E Status Is Inversely Associated with Risk of Incident Tuberculosis Disease among Household Contacts.

Background: Few studies have previously assessed how pre-existing vitamin E status is associated with risk of tuberculosis (TB) disease progression. Objective: We evaluated the association between baseline plasma concentrations of 3 vitamin E isomers (α-tocopherol, γ-tocopherol, and δ-tocopherol) and TB disease risk. Methods: We conducted a case-control study nested within a longitudinal cohort of household contacts (HHCs) of pulmonary TB cases in Lima, Peru. We defined cases as HHCs who developed active TB disease ≥15 d after the diagnosis of the index patient, and we matched each case to 4 control cases who did not develop active TB based on age by year and gender. We used univariate and multivariate conditional logistic regression to calculate ORs for incident TB disease by plasma concentrations of α-tocopherol, γ-tocopherol, and δ-tocopherol. Results: Among 6751 HIV-negative HHCs who provided baseline blood samples, 180 developed secondary TB during follow-up. After controlling for possible confounders, we found that baseline α-tocopherol deficiency conferred increased risk of incident TB disease (adjusted OR: 1.59; 95% CI: 1.02, 2.50; P = 0.04). Household contacts in the lowest tertile of δ-tocopherol were also at increased risk of progression to TB disease compared to those in the highest tertile (tertile 1 compared with tertile 3, adjusted OR: 2.29; 95% CI: 1.29, 4.09; P-trend = 0.005). We found no association between baseline concentration of γ-tocopherol and incident TB disease. Conclusions: Vitamin E deficiency was associated with an increased risk of progression to TB disease among HHCs of index TB cases. Assessment of vitamin E status among individuals at high risk for TB disease may play a role in TB control efforts.

Impact of Vitamin A and Carotenoids on the Risk of Tuberculosis Progression.

BACKGROUND: Low and deficient levels of vitamin A are common in low- and middle-income countries where tuberculosis burden is high. We assessed the impact of baseline levels of vitamin A and carotenoids on tuberculosis disease risk. METHODS: We conducted a case-control study nested within a longitudinal cohort of household contacts (HHCs) of pulmonary tuberculosis case patients in Lima, Peru. We defined case patients as human immunodeficiency virus (HIV)-negative HHCs with blood samples in whom tuberculosis disease developed ≥15 days after enrollment of the index patient. For each case patient, we randomly selected 4 controls from among contacts in whom tuberculosis disease did not develop, matching for sex and year of age. We used conditional logistic regression to estimate odds ratios for incident tuberculosis disease by vitamin A and carotenoids levels, controlling for other nutritional and socioeconomic factors. RESULTS: Among 6751 HIV-negative HHCs with baseline blood samples, 192 had secondary tuberculosis disease during follow-up. We analyzed 180 case patients with viable samples and 709 matched controls. After controlling for possible confounders, we found that baseline vitamin A deficiency was associated with a 10-fold increase in risk of tuberculosis disease among HHCs (adjusted odds ratio, 10.53; 95% confidence interval, 3.73-29.70; P < .001). This association was dose dependent, with stepwise increases in tuberculosis disease risk with each decreasing quartile of vitamin A level. CONCLUSIONS: Vitamin A deficiency strongly predicted the risk of incident tuberculosis disease among HHCs of patients with tuberculosis. Vitamin A supplementation among individuals at high risk of tuberculosis may provide an effective means of preventing tuberculosis disease.

Nutritional Status and Tuberculosis Risk in Adult and Pediatric Household Contacts.

BACKGROUND: Studies show obesity decreases risk of tuberculosis (TB) disease. There is limited evidence on whether high body mass index also protects against TB infection; how very high body mass indices influence TB risk; or whether nutritional status predicts this risk in children. We assessed the impact of body mass index on incident TB infection and disease among adults and children. METHODS AND FINDINGS: We conducted a prospective cohort study among household contacts of pulmonary TB cases in Lima, Peru. We determined body mass index at baseline and followed participants for one year for TB infection and disease. We used Cox proportional regression analyses to estimate hazard ratios for incident TB infection and disease. We enrolled 14,044 household contacts, and among 6853 negative for TB infection and disease at baseline, 1787 (26.1%) became infected. A total of 406 contacts developed secondary TB disease during follow-up. Body mass index did not predict risk of TB infection but overweight household contacts had significantly decreased risk of TB disease (HR 0.48; 95% CI 0.37-0.64; p <0.001) compared to those with normal weight. Among adults, body mass index ≥ 35 kg/m2 continued to predict a lower risk of TB disease (HR 0.30; 95% CI 0.12-0.74; p 0.009). We found no association between high body mass index and TB infection or disease among children under 12 years of age. CONCLUSIONS: High body mass index protects adults against TB disease even at levels ≥ 35 kg/m2. This protective effect does not extend to TB infection and is not seen in children.

The effect of HIV-related immunosuppression on the risk of tuberculosis transmission to household contacts.

BACKGROUND: Coinfection with human immunodeficiency virus (HIV) may modify the risk of transmitting tuberculosis. Some previous investigations suggest that patients coinfected with HIV and tuberculosis are less likely to transmit infection, whereas others do not support this conclusion. Here, we estimated the relative risk of tuberculosis transmission from coinfected patients compared to HIV-negative patients with tuberculosis. METHODS: Between September 2009 and August 2012, we identified and enrolled 4841 household contacts of 1608 patients with drug-sensitive tuberculosis in Lima, Peru. We assessed the HIV status and CD4 counts of index patients, as well as other risk factors for infection specific to the index patient, the household, and the exposed individuals. Contacts underwent tuberculin skin testing to determine tuberculosis infection status. RESULTS: After adjusting for covariates, we found that household contacts of HIV-infected tuberculosis patients with a CD4 count ≤250 cells/µL were less likely to be infected with tuberculosis (risk ratio = 0.49 [95% confidence interval, .24-.96]) than the contacts of HIV-negative tuberculosis patients. No children younger than 15 years who were exposed to HIV-positive patients with a CD4 count ≤250 cells/µL were infected with tuberculosis, compared to 22% of those exposed to non-HIV-infected patients. There was no significant difference in the risk of infection between contacts of HIV-infected index patients with CD4 counts >250 cells/µL and contacts of index patients who were not HIV-infected. CONCLUSIONS: We found a reduced risk of tuberculosis infection among the household contacts of patients with active tuberculosis who had advanced HIV-related immunosuppression, suggesting reduced transmission from these index patients.