Latent tuberculosis infection: the final frontier of tuberculosis elimination in the USA

Development and validation of prediction algorithm to identify tuberculosis in two large California health systems

California data demonstrate failures in latent tuberculosis screening to prevent progression to tuberculosis disease. Therefore, we developed a clinical risk prediction model for tuberculosis disease using electronic health records. This study included Kaiser Permanente Southern California and Northern California members ≥18 years during 2008-2019. Models used Cox proportional hazards regression, Harrell's C-statistic, and a simulated TB disease outcome accounting for cases prevented by current screening which includes both observed and simulated cases. We compared sensitivity and number-needed-to-screen for model-identified high-risk individuals with current screening. Of 4,032,619 and 4,051,873 Southern and Northern California members, tuberculosis disease incidences were 4.1 and 3.3 cases per 100,000 person-years, respectively. The final model C-statistic was 0.816 (95% simulation interval 0.805-0.824). Model sensitivity screening high-risk individuals was 0.70 (0.68-0.71) and number-needed-to-screen was 662 (646-679) persons-per tuberculosis disease case, compared to a sensitivity of 0.36 (0.34-0.38) and number-needed-to-screen of 1632 (1485-1774) with current screening. Here, we show our predictive model improves tuberculosis screening efficiency in California.

Identification and functional characterization of glycosyltransferase-related biomarkers for tuberculosis diagnosis

Tuberculosis (TB) is an infectious disease that presents a serious risk to public health. Glycosyltransferase-related genes (GTRGs) are instrumental in assessing the risk of latent tuberculosis infection progressing to active TB. This study aims to develop novel, accurate, and effective diagnostic markers to enhance the early diagnosis and precision treatment of TB. We employed Weighted Gene Co-expression Network Analysis (WGCNA) to explore key genes that are notably linked toTB. In addition, we employed single-sample Gene Set Enrichment Analysis (ssGSEA) to examine the differences in immune cell infiltration between normal tissues and those affected by TB. The effectiveness of the potential biomarkers was evaluated through Receiver Operating Characteristic (ROC) curves and their expression patterns. We also conducted single-gene enrichment analysis to explore the biological functions and pathway activities linked to the characteristic genes. Finally, we constructed a competitive endogenous RNA (ceRNA) network to elucidate the potential regulatory mechanisms governing these genes. Through the screening of hub genes and differentially expressed genes from the GTRGs, we identified two potential biomarkers: B4GALT5 and KCNJ2. Evaluation results indicated that these characteristic genes displayed strong diagnostic performance in both the training and validation cohorts. Moreover, single-gene enrichment analysis revealed that these genes were primarily enriched in apoptosis pathways closely associated with TB treatment. Additionally, the construction of the mRNA-miRNA-lncRNA network identified 82 miRNAs and 65 lncRNAs. This study elucidates the roles of GTRGs in TB, identifies biomarkers associated with these groups, and establishes the lncRNA expression profile of characteristic genes. These findings provide a theoretical foundation for the early diagnosis of TB.

Knowledge and Prevalence of Latent Tuberculosis Infection: A Feasibility and Pilot Study in a Primary Healthcare Setting in Rural Eastern Cape, South Africa

Latent tuberculosis infection (LTBI) remains a significant global health concern, particularly in regions with high tuberculosis (TB) prevalence, such as South Africa. This pilot study aimed to evaluate the prevalence of LTBI and assess patient knowledge about the condition in a primary healthcare clinic in rural Eastern Cape, South Africa. A cross-sectional design was used, and convenience sampling recruited outpatients aged 18 years and older with no prior history of TB. Blood samples were analyzed using the QuantiFERON-TB Gold assay to determine LTBI status, and a survey assessed patient knowledge of LTBI. Strong positive correlations were observed between what patients understand by the term LTBI and how LTBI differs from TB (0.70), what patients understand by the term LTBI and the risk factors for developing LTBI (0.70), how LTBI differs from TB and the risk factors for developing LTBI (0.78), and how LTBI differs from TB and the recommended treatments for LTBI (0.79), indicating overlap in understanding. In contrast, there were negative correlations between if patients had ever heard of latent LTBI before and their understanding of the term LTBI (-0.25), the risk factors for developing LTBI (-0.22), LTBI progressing to active TB (-0.27), and the recommended treatments for LTBI (-0.27). This divergence points to different dimensions of patient knowledge and awareness. Age, gender, occupation, comorbidities, and HIV status showed varying LTBI positivity trends. Among younger patients aged 20-29, 15.4% tested positive, while the 30-39 group showed a nearly equal split between positive (48.1%) and negative cases. A higher positivity rate was seen in females (39.1%) compared to males (31.6%). Unemployed individuals had higher positivity rates, suggesting socioeconomic factors' influence. Comorbidities, especially hypertension, diabetes, and asthma, correlated with higher LTBI positivity among females, but this was less evident in males. HIV-positive patients had a higher LTBI-negative rate compared to HIV-negative patients. A logistic regression model (accuracy 70%) identified demographic and health factors predicting LTBI outcomes, with comorbidities, particularly hypertension and diabetes, significantly increasing the likelihood of LTBI positivity. These findings suggest that demographic and health factors, including age, gender, occupation, comorbidities, and HIV status, may predict LTBI positivity.

Process and Outcome Evaluation of the Centers for Disease Control and Prevention's Think. Test. Treat TB Health Communications Campaign, United States, March-September 2022

OBJECTIVES

The Think. Test. Treat TB health communications campaign aims to increase the awareness of latent tuberculosis infection (LTBI) primarily among people born in the Philippines and Vietnam and other non-US-born groups (consumers) and the health care providers (providers) who serve them. We conducted a process evaluation to assess reach and audience engagement and an outcome evaluation to assess awareness, knowledge, perceptions, and behavioral intentions among audiences of the campaign.

METHODS

To evaluate the process, the Centers for Disease Control and Prevention measured exposure to (eg, with impressions [total advertisements]) and engagement with (eg, online clicks) the campaign during its rollout (March-September 2022). After the rollout, to evaluate outcomes, we administered online surveys to consumers and providers who were exposed and not exposed to the campaign.

RESULTS

The Think. Test. Treat TB campaign resulted in >33 million impressions, >2000 materials downloaded from the internet, and >33 000 materials shipped. Of 173 consumers who completed the evaluation survey, 123 (71.1%) were exposed to the campaign, with 108 (87.8%) reporting intention to ask their provider about tuberculosis (TB) during their next visit. Of 44 providers who completed the evaluation survey, 24 (54.5%) did not feel that they were the intended audience of the campaign, yet all felt the campaign materials were relevant to their patients, and 42 (95.5%) felt the materials were relevant to providers who serve patients at risk for TB.

CONCLUSION

The Think. Test. Treat TB campaign was successful in raising awareness of LTBI among the intended audiences. Continuing engagement with key audiences about LTBI to encourage testing and treatment is integral to eliminate TB in the United States.

The problem that residual Mycobacterium bovis infection poses for the eradication of bovine tuberculosis

The dynamics of Mycobacterium bovis infection in cattle can influence the proportion of infected animals that are diagnosed by ante-mortem tests in routine bovine tuberculosis (bTB) surveillance and monitoring programmes. Although the current diagnostic tests based on cell-mediated or serological responses are imperfect, they are effective in diagnosing the majority of infected animals. However, the lack of perfect sensitivity and specificity also leads to failure to diagnose all infected animals leading to persistence of infection in herds. The terms residual, subclinical, latent and anergy have been used interchangeably to denote the presence of continued undiagnosed M. bovis infection within cattle herds, which ultimately hinders the eradication of bTB and imposes substantial financial burdens on farming communities and national economies. Epidemiological data suggests the existence of M. bovis-infected, but often undetected, cattle within herds that contribute to eradication failure. This has similarities with human tuberculosis, caused by Mycobacterium tuberculosis, where latent infection is defined as the persistence of viable but quiescent bacilli for extended periods in patients without clinical symptoms but with a detectable immune response to M. tuberculosis antigens. If a similar infection state exists in cattle infected with M. bovis, the persistence of such animals in disease-managed herds is unlikely to be common given that those found to have positive immune responses to M. bovis antigens are routinely culled to minimise future risk of transmission. Apart from contributing to the burden of herd infection, such residual infection without detection may also 'seed' recipient herds following animal movements, and potentially play an important role in the overall epidemiology of bTB as the prevalence of disease decreases and the attendant altered predictive value of the diagnostic tests result in a greater proportion of infected animals remaining undetected. This review examines how the different stages of M. bovis infection in cattle may contribute to the failure to diagnose infected animals using conventional testing methodologies and the attendant risk this poses in creating prolonged or recurrent herd breakdowns.

Randomized Controlled Trial of Clinical Guidelines Versus Interactive Decision-Support for Improving Medical Trainees' Confidence with Latent Tuberculosis Care

BACKGROUND

In order to eliminate tuberculosis (TB) in the USA, primary care providers must take on an expanded role in the diagnosis and management of latent tuberculosis infection (LTBI). Clinical practice guidelines and recommendations exist for LTBI management, but there is a need for innovative tools to improve medical students' and residents' knowledge of evidence-based practices for LTBI testing and treatment.

OBJECTIVE

To assess the impact of LTBI-ASSIST, a free online decision support aid, as a novel educational tool and mechanism of delivering clinical practice guidelines for medical trainees.

DESIGN

A single site, randomized controlled trial of trainees delivered by electronic survey.

INTERVENTIONS

Medical students and Internal Medicine residents at the Johns Hopkins University School of Medicine.

PARTICIPANTS

Participants were randomized in 1:1 ratio to receive the US clinical practice guidelines and recommendations for Latent TB management (control arm) or the guidelines plus an introduction to LTBI-ASSIST (LTBI-ASSIST arm) as they completed a case-based knowledge assessment and reported confidence with domains of LTBI care.

MAIN MEASURES

(1) Proportion of questions answered correctly on a case-based knowledge assessment; (2) change in reported confidence with domains of LTBI care.

KEY RESULTS

One hundred and thirty participants completed the knowledge assessment. Those randomized to receive the LTBI-ASSIST Tool performed better on the case-based knowledge assessment with a mean score of 75.9% (95% CI: 70.6-81.1), compared to 57.4% (52.8-62.0) in the group that received the guidelines only (p <0.001). Similarly, the LTBI-ASSIST group reported a higher change in confidence (measured as post-assessment confidence minus pre-assessment confidence), compared to the control group, in six of the seven domains of LTBI care.

CONCLUSIONS

LTBI-ASSIST can be an effective supplement to existing guidelines in educating medical trainees and helping providers find evidence-based, guideline-supported answers for questions encountered in clinical practice.

TRIAL REGISTRATION

NIH Clinical Trial Registry No. NCT05772065.

Interpreter usage and associations with latent tuberculosis infection treatment acceptance and completion in the USA among non-U.S.-born persons, 2012-2017

BACKGROUND

Latent tuberculosis infection (LTBI) screening and treatment interventions that are tailored to optimize acceptance among the non-U.S.-born population are essential for U.S. tuberculosis elimination. We investigated the impact of medical interpreter use on LTBI treatment acceptance and completion among non-U.S.-born persons in a multisite study.

METHODS

The Tuberculosis Epidemiologic Studies Consortium was a prospective cohort study that enrolled participants at high risk for LTBI at ten U.S. sites with 18 affiliated clinics from 2012 to 2017. Non-U.S.-born participants with at least one positive tuberculosis infection test result were included in analyses. Characteristics associated with LTBI treatment offer, acceptance, and completion were evaluated using multivariable logistic regression with random intercepts to account for clustering by enrollment site. Our primary outcomes were whether use of an interpreter was associated with LTBI treatment acceptance and completion. We also evaluated whether interpreter usage was associated treatment offer and whether interpreter type was associated with treatment offer, acceptance, or completion.

RESULTS

Among 8,761 non-U.S.-born participants, those who used an interpreter during the initial interview had a significantly greater odds of accepting LTBI treatment than those who did not use an interpreter. There was no association between use of an interpreter and a clinician's decision to offer treatment or treatment completion once accepted. Characteristics associated with lower odds of treatment being offered included experiencing homelessness and identifying as Pacific Islander persons. Lower treatment acceptance was observed in Black and Latino persons and lower treatment completion by participants experiencing homelessness. Successful treatment completion was associated with use of shorter rifamycin-based regimens. Interpreter type was not associated with LTBI treatment offer, acceptance, or completion.

CONCLUSIONS

We found greater LTBI treatment acceptance was associated with interpreter use among non-U.S.-born individuals.

Asynchronous Video Directly Observed Therapy to Monitor Short-Course Latent Tuberculosis Infection Treatment: Results of a Randomized Controlled Trial

Background

Observing medication ingestion through self-recorded videos (video directly observed therapy [VDOT]) has been shown to be a cost-effective alternative to in-person directly observed therapy (DOT) for monitoring adherence to treatment for tuberculosis disease. VDOT could be a useful tool to monitor short-course latent tuberculosis infection (LTBI) treatment.

Methods

We conducted a prospective randomized controlled trial comparing VDOT (intervention) and clinic-based DOT (control) among patients newly diagnosed with LTBI who agreed to a once-weekly 3-month treatment regimen of isoniazid and rifapentine. Study outcomes were treatment completion and patient satisfaction. We also assessed costs. Pre- and posttreatment interviews were conducted.

Results

Between March 2016 and December 2019, 130 participants were assigned to VDOT (n = 68) or DOT (n = 62). Treatment completion (73.5% vs 69.4%, P = .70) and satisfaction with treatment monitoring (92.1% vs 86.7%, P = .39) were slightly higher in the intervention group than the control group, but neither was statistically significant. VDOT cost less per patient (median, $230; range, $182-$393) vs DOT (median, $312; range, $246-$592) if participants used their own smartphone.

Conclusions

While both groups reported high treatment satisfaction, VDOT was not associated with higher LTBI treatment completion. However, VDOT cost less than DOT. Volunteer bias might have reduced the observed effect since patients opposed to any treatment monitoring could have opted for alternative unobserved regimens. Given similar outcomes and lower cost, VDOT may be useful for treatment monitoring when in-person observation is prohibited or unavailable (eg, during a respiratory disease outbreak). The trial was registered at the National Institutes of Health (ClinicalTrials.gov NTC02641106).

Clinical Trials Registration

ClinicalTrials.gov NTC02641106; registered 24 October 2016.

Tuberculosis - United States, 2023

After 27 years of declining U.S. tuberculosis (TB) case counts, the number of TB cases declined considerably in 2020, coinciding with the COVID-19 pandemic. For this analysis, TB case counts were obtained from the National TB Surveillance System. U.S. Census Bureau population estimates were used to calculate rates overall, by jurisdiction, birth origin, race and ethnicity, and age group. Since 2020, TB case counts and rates have increased each year. During 2023, a total of 9,615 TB cases were provisionally reported by the 50 U.S. states and the District of Columbia (DC), representing an increase of 1,295 cases (16%) as compared with 2022. The rate in 2023 (2.9 per 100,000 persons) also increased compared with that in 2022 (2.5). Forty states and DC reported increases in 2023 in both case counts and rates. National case counts increased among all age groups and among both U.S.-born and non-U.S.-born persons. Although TB incidence in the United States is among the lowest in the world and most U.S. residents are at minimal risk, TB continues to cause substantial global morbidity and mortality. This postpandemic increase in U.S. cases highlights the importance of continuing to engage communities with higher TB rates and their medical providers in TB elimination efforts and strengthening the capacity in public health programs to carry out critical disease control and prevention strategies.

Treatment of Psoriasis Patients with Latent Tuberculosis Using IL-17 and IL-23 Inhibitors: A Retrospective, Multinational, Multicentre Study

BACKGROUND

Tuberculosis has a major global impact. Immunocompetent hosts usually control this disease, resulting in an asymptomatic latent tuberculosis infection (LTBI). Because TNF inhibitors increase the risk of tuberculosis reactivation, current guidelines recommend tuberculosis screening before starting any biologic drug, and chemoprophylaxis if LTBI is diagnosed. Available evidence from clinical trials and real-world studies suggests that IL-17 and IL-23 inhibitors do not increase the risk of tuberculosis reactivation.

OBJECTIVE

To evaluate psoriasis patients with treated or untreated newly diagnosed LTBI who received IL-17 and IL-23 inhibitors and the tolerability/safety of tuberculosis chemoprophylaxis.

METHODS

This is a retrospective, observational, multinational study from a series of 14 dermatology centres based in Portugal, Spain, Italy, Greece and Brazil, which included adult patients with moderate-to-severe chronic plaque psoriasis and newly diagnosed LTBI who were treated with IL-23 or IL-17 inhibitors between January 2015 and March 2022. LTBI was diagnosed in the case of tuberculin skin test and/or interferon gamma release assay positivity, according to local guideline, prior to initiating IL-23 or IL-17 inhibitor. Patients with prior diagnosis of LTBI (treated or untreated) or treated active infection were excluded.

RESULTS

A total of 405 patients were included; complete/incomplete/no chemoprophylaxis was administered in 62.2, 10.1 and 27.7% of patients, respectively. The main reason for not receiving or interrupting chemoprophylaxis was perceived heightened risk of liver toxicity and hepatotoxicity, respectively. The mean duration of biological treatment was 32.87 ± 20.95 months, and only one case of active tuberculosis infection (ATBI) was observed, after 14 months of treatment with ixekizumab. The proportion of ATBI associated with ixekizumab was 1.64% [95% confidence interval (CI): 0-5.43%] and 0% for all other agents and 0.46% (95% CI 0-1.06%) and 0% for IL-17 and IL-23 inhibitors, respectively (not statistically significant).

CONCLUSIONS

The risk of tuberculosis reactivation in patients with psoriasis and LTBI does not seem to increase with IL-17 or IL-23 inhibitors. IL-17 or IL-23 inhibitors should be preferred over TNF antagonists when concerns regarding tuberculosis reactivation exists. In patients with LTBI considered at high risk for developing complications related to chemoprophylaxis, this preventive strategy may be waived before initiating treatment with IL-17 inhibitors and especially IL-23 inhibitors.

Test and treat approach for tuberculosis infection amongst household contacts of drug-susceptible pulmonary tuberculosis, Mumbai, India

Background

Mumbai is one of the most densely populated areas in the world and is a major contributor to the tuberculosis (TB) epidemic in India. A test and treat approach for TB infection (TBI) amongst household contacts (HHC) is part of the national policy for TB preventive treatment (TPT). However, in practice, the use of interferon-gamma release assay (IGRA) tests for infection are limited, and prevalence of TBI in Mumbai is not known.

Methods

We conducted a cross-sectional study among HHCs exposed to persons with microbiologically-confirmed, drug-susceptible pulmonary TB that were notified for antituberculosis treatment in Mumbai, India during September-December, 2021. Community-based field workers made home visits and offered IGRA (QuantiFERON-TB® Gold In-Tube Plus) tests to HHC aged 5 years and older. After ruling out active TB disease, HHC with IGRA-positive test results were referred for TPT. All HHC were monitored for at least 24 months for progression to active TB disease.

Results

Among 502 HHCs tested, 273 (54%) had IGRA-positive results. A total of 254 (93%) were classified as TBI and were eligible for TPT, of which 215 (85%) initiated TPT, and 194 (90%) completed TPT successfully. There was substantial variation in rates of TBI per household. In 32% of households, all HHC (100%) were IGRA positive and in 64% of households >50% of HHC were infected. In all, 22 HHCs (4%; 22/558) were diagnosed with TB disease; of these, five HHC were diagnosed during follow up, of which three were IGRA positive and had no evidence of disease at initial screening but chose not to initiate TPT.

Conclusion

A test and treat strategy for HHC resulted in the detection of a substantial proportion of TBI and secondary TB cases. Home-based IGRA testing led to high participation rates, clinical evaluations, TPT initiation, and early diagnoses of additional secondary cases. A community-focused, test and treat approach was feasible in this population and could be considered for broader implementation.

Trends in tuberculosis clinicians' adoption of short-course regimens for latent tuberculosis infection

Objective

Little is known about regimen choice for latent tuberculosis infection in the United States. Since 2011, the Centers for Disease Control and Prevention has recommended shorter regimens-12 weeks of isoniazid and rifapentine or 4 months of rifampin-because they have similar efficacy, better tolerability, and higher treatment completion than 6-9 months of isoniazid. The objective of this analysis is to describe frequencies of latent tuberculosis infection regimens prescribed in the United States and assess changes over time.

Methods

Persons at high risk for latent tuberculosis infection or progression to tuberculosis disease were enrolled into an observational cohort study from September 2012-May 2017, tested for tuberculosis infection, and followed for 24 months. This analysis included those with at least one positive test who started treatment.

Results

Frequencies of latent tuberculosis infection regimens and 95% confidence intervals were calculated overall and by important risk groups. Changes in the frequencies of regimens by quarter were assessed using the Mann-Kendall statistic. Of 20,220 participants, 4,068 had at least one positive test and started treatment: 95% non-U.S.-born, 46% female, 12% <15 years old. Most received 4 months of rifampin (49%), 6-9 months of isoniazid (32%), or 12 weeks of isoniazid and rifapentine (13%). Selection of short-course regimens increased from 55% in 2013 to 81% in late 2016 (p < 0.001).

Conclusions

Our study identified a trend towards adoption of shorter regimens. Future studies should assess the impact of updated treatment guidelines, which have added 3 months of daily isoniazid and rifampin to recommended regimens.

Association of Mycobacterium tuberculosis infection test results with risk factors for tuberculosis transmission

Background

Close contacts infected with Mycobacterium tuberculosis are at high risk of tuberculosis (TB) disease and a priority for preventive treatment. Three tests measure infection: two interferon-gamma release assays (IGRAs) and the tuberculin skin test (TST). The objective of our study was to assess the association of positive test results in contacts with infectiousness of the presumed TB source case.

Methods

Contacts in a cohort study at 10 United States sites received both IGRAs (QuantiFERON-TB Gold In-Tube (QFT-GIT) and T-SPOT.TB (T-SPOT)) and TST. We defined test conversion as negative for all tests at baseline and positive for at least one on retest. Risk ratios (RR) and 95% confidence intervals (CI) assessed association of positive test results with increased infectiousness of the TB case-defined as acid-fast bacilli (AFB) on sputum microscopy or cavities on chest radiographs- and contact demographics.

Results

Adjusted for contacts' age, nativity, sex, and race, IGRAs (QFT-GIT RR = 6.1, 95% CI 1.7-22.2; T-SPOT RR = 9.4, 95% CI 1.1-79.1), but not TST (RR = 1.7, 95% CI 0.8-3.7), were more likely to convert among contacts exposed to persons with cavitary TB disease.

Conclusions

Because IGRA conversions in contacts are associated with infectiousness of the TB case, their use may improve efficiency of health department contact investigations by focusing efforts on those likely to benefit from preventive treatment in the United States.

Scaling Up Latent Tuberculosis Infection Testing and Treatment for Non-US Born Patients in a Federally Qualified Community Health Center

In the United States (US), tuberculosis elimination strategies include scaling up latent tuberculosis infection (LTBI) diagnosis and treatment for persons at risk of progression to tuberculosis disease. The Massachusetts Department of Public Health partnered with Lynn Community Health Center to provide care to patients with LTBI who were born outside the US. The electronic health record was modified to facilitate collection of data elements for public health assessment of the LTBI care cascade. Among health center patients born outside the US, testing for tuberculosis infection increased by over 190%. From October 1, 2016 to March 21, 2019, 8827 patients were screened and 1368 (15.5%) were diagnosed with LTBI. Using the electronic health record, we documented treatment completion for 645/1368 (47.1%) patients. The greatest drop-offs occurred between testing for TB infection and clinical evaluation after a positive test (24.3%) and between the recommendation for LTBI treatment and completion of a treatment course (22.8%). Tuberculosis care delivery was embedded in the primary care medical home, bringing patient-centered care to those at high risk for loss to follow up. The partnership between public health and the community health center promoted quality improvement.

The association of blood metals with latent tuberculosis infection among adults and adolescents

Objective

We aimed to investigate the relationship of metal exposure and latent tuberculosis infection (LTBI) among US adults and adolescents.

Methods

Participants from the National Health and Nutrition Examination Surveys (NHANES 2011 ~ 2012) were included. Multiple logistic regression models were used to explore the associations between metal exposure and LTBI. A total of 5,248 adults and 1,860 adolescents were included in the present analysis.

Results

For adults, we only found a positive association between total mercury and LTBI (OR: 1.411; 95% CI: 1.164 ~ 1.710) when used as a continuous variable. Compared with Q1, Q4 increased the prevalence of LTBI (2.303; 1.455 ~ 3.644) when used as a quartile. The OR of total mercury and LTBI was higher among females (1.517; 1.009 ~ 2.279), individuals aged 45 ~ 64 (1.457; 1.060 ~ 2.002), and non-Hispanic White individuals (1.773; 1.316 ~ 2.388). A relationship was observed among only participants with obesity (1.553; 1.040 ~ 2.319) or underweight (1.380; 1.076 ~ 1.771), with college or above (1.645; 1.184 ~ 2.286), with PIR > 3.0 (1.701; 1.217 ~ 2.376), reported smoking (1.535; 1.235 ~ 1.907) and drinking (1.464; 1.232 ~ 1.739). For adolescents, blood manganese was positively associated with LTBI. The OR and 95% CIs for each one-unit increase in the log-transformed level of blood manganese with LTBI were 9.954 (1.389 ~ 71.344).

Conclusion

Significant associations were observed in girls, aged ≥12 years and in the non-Hispanic white population. In conclusion, total mercury is associated with an increased prevalence of LTBI among adults and positive association between blood manganese and LTBI was observed among adolescents. Further studies should be conducted to verify the results and explore potential biological mechanisms.

Gut microbiota composition and diversity before, during, and two months after rifamycin-based tuberculosis preventive therapy

Tuberculosis (TB) preventive therapy (TPT) is an effective strategy to eliminate TB in low-incidence settings. Shorter TPT regimens incorporating the antimicrobial class of rifamycins are designed to improve adherence and completion rates but carry the risk of modifications to the gut microbiota. We enrolled six subjects diagnosed with latent TB infection (LTBI) who accepted to initiate TPT. We also enrolled six healthy volunteers unexposed to the rifamycins. We profiled the gut microbiota using 16S rRNA amplicon sequencing (V1-V2 region) to document the immediate effect of rifamycin-based TPT on the gut microbiota composition and tracked recovery to baseline two months after TPT. Overall, TPT accounted for 17% of the variance in gut microbial community dissimilarity. This rifamycin-based TPT induced dysbiosis was characterized by a depletion of butyrate-producing taxa (Clostridium-XIVa and Roseburia) and expansion of potentially pathogenic taxa within the Firmicutes and Proteobacteria phyla. Recovery of the gut microbial composition was incomplete two months after TPT. Robust clinical studies are necessary to comprehensively catalogue TPT-induced gut microbiota dysbiosis to inform strategies to mitigate potential long-term sequelae of this important TB control intervention.

Identification of the key genes of tuberculosis and construction of a diagnostic model via weighted gene co-expression network analysis

BACKGROUND

Tuberculosis (TB) is an infectious disease with high mortality, and mining key genes for TB diagnosis is vital to raise the survival rate of patients.

METHODS

The whole microarray datasets GSE83456 (training set) and GSE19444 (validation set) of TB patients were downloaded from the Gene Expression Omnibus (GEO) database. Differential expression was conducted on genes between TB and normal samples (unconfirmed TB) in GSE83456 to yield TB-related differentially expressed genes (DEGs). DEGs were subjected to weighted gene co-expression network analysis (WGCNA) and clustered to form distinct gene modules. The immune scores of 25 kinds of immune cells were obtained by single-sample gene set enrichment analysis (ssGSEA) of TB samples, and Pearson correlation analysis was carried out between the 25 immune scores and diverse gene modules. The gene modules significantly associated with immune cells were retained as Target modules. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed on the genes in the modules (p-value <0.05). The protein-protein interaction (PPI) network was established utilizing the STRING database for genes in the Target module, and the selected key genes were intersected with immune-related genes in the ImmPort database. The obtained immune-related module genes were used for subsequent least absolute shrinkage and selection operator (LASSO) regression analysis and diagnostic models were constructed. Finally, the receiver operating characteristic (ROC) curve was utilized to validate the diagnostic model.

RESULTS

The turquoise and yellow modules had a high correlation with macrophages. LASSO regression analysis of immune-related genes in TB was carried on to finally construct a 5-gene diagnostic model composed of C5, GRN, IL1B, IL23A, and TYMP. As demonstrated by the ROC curves, the diagnostic efficiency of this diagnostic model was 0.957 and 0.944 in the training and validation sets, respectively. Therefore, the immune-related 5-gene model had a good diagnostic function for TB.

CONCLUSION

We identified 5 immune-related diagnostic markers that may play an important role in TB, and verified that this immune-related key gene model had a good diagnostic performance.

Prior Screening for Latent Tuberculosis Among Patients Diagnosed With Tuberculosis Disease: Missed Opportunities?

Background

California has the largest number of tuberculosis (TB) disease cases in the United States. This study in a large California health system assessed missed opportunities for latent tuberculosis (LTBI) screening among patients with TB disease.

Methods

Kaiser Permanente Southern California patients who were ≥18 years old with membership for ≥24 months during the study period from 1 January 2008 to 31 December 2019 were included. Prior LTBI test (tuberculin skin test or interferon-γ release assay) or diagnosis code prior to TB disease diagnosis was assessed among patients with observed TB disease (confirmed by polymerase chain reaction and/or culture). In the absence of current treatment practices, more patients screened for LTBI may have developed TB disease. We estimated hypothetical TB disease cases prevented by multiplying LTBI progression rates by the number of LTBI-positive patients prescribed treatment.

Results

A total of 1289 patients with observed TB disease were identified; 148 patients were LTBI positive and 84 were LTBI negative. Patients not prescreened for LTBI made up 82.0% of observed TB disease cases (1057/1289). Adding the hypothetical maximum estimate for prevented cases decreased the percentage of patients who were not prescreened for LTBI to 61.7% [1057/(1289 + 424)].

Conclusions

One-fifth of patients were screened for LTBI prior to their active TB diagnosis. Assuming the upper bound of cases prevented through current screening, almost 62% of TB disease patients were never screened for LTBI. Future work to elucidate gaps in LTBI screening practices and to identify opportunities to improve screening guidelines is needed.

Latent tuberculosis infection in the outpatient general medicine clinic: Efficacy of a nurse-run electronic directly observed treatment program

Tuberculosis (TB) is a leading cause of infectious death worldwide, with nearly 2 billion currently infected globally. While the largest burden of active TB resides in low to middle-income countries, the US contributes to the global epidemic and can play a significant role in interrupting the spread of TB by recognizing and treating latent TB infection (LTBI). The vast majority of active TB in the US originates from the reactivation of LTBI. This cross-sectional study examines the prevalence of LTBI in a general medicine practice and explores the efficacy of a primary care nurse-run electronic directly observed therapy (eDOT) treatment program. 1221 patients were screened for the presence of historical risk factors for LTBI. Of those screened, 192 were offered QuantiFERON-TB Gold Plus (QFT-Plus) testing and a CXR if indicated, resulting in 35 being offered treatment for LTBI. After an initial provider visit to decide on the treatment regimen, patients received weekly nurse calls to verify adherence, assess for side effects and answer additional patient questions. Provider follow-up appointments occurred at the midpoint and completion of treatment. 33 (94%) of patients with LTBI completed treatment. Patients found the nurse calls very helpful to reassure them about their treatment and to address treatment concerns. Primary care providers are particularly well-positioned to identify and treat LTBI. Screening is simple and treatment is generally well tolerated. Utilization of a nurse-run eDOT) program can be quite helpful in facilitating adherence and treatment completion.

Diagnostic Value of CD25, CD69, and CD134 on Tuberculosis-Specific Antigen-Stimulated CD4+ T Cells for Tuberculous Pleurisy

Rapid and accurate methods for the diagnosis of tuberculous pleurisy (TP) are urgently needed. Activation markers of tuberculosis (TB)-reactive T cells are considered promising for the diagnosis of active TB (ATB). Different activation indexes may play different roles in the progression of TB, but there are few reports on T cell activation indicators, except for HLA-DR. Hence, we evaluated the expression of early (CD25 and CD69) and late (CD134) activation markers on TB antigen-stimulated CD4+ T cells in populations with different TB infection status and investigated their diagnostic value for ATB, particularly, for TP. Moreover, we compared the differences in the diagnostic efficacy among the indexes from peripheral blood (PB) and pleural fluid (PF) for TP. The expression of each activation marker was significantly increased in TB-infected populations (patients with ATB and latent TB infection vs. healthy individuals; patients with TP vs. non-TP) and was significantly higher in the PF than in the PB of patients with TP. The diagnostic performance of the coexpressed activation markers was superior to that of single expression markers in the differential diagnosis of ATB and non-TB, with CD25+CD134+ showing the best diagnostic efficiency (AUC: 0.93, 95% CI, 0.87-0.99; sensitivity: 86.7%, 95% CI, 72.5%-94.5%; and specificity: 94.0%, 95% CI, 82.5%-98.4%). Except for TB-IGRA, the activation indexes were more accurate than conventional laboratory methods for ATB diagnosis. In addition, the expression of CD25+CD134+ in PB and PF was the best values for differential diagnosis of TP and NTP, with AUCs of 0.87 (95% CI, 0.77-0.96) and 0.95 (95% CI, 0.90-1.00), respectively. Our study provides information on the diagnostic value of different activation markers for TB and shows that the expression of CD25+CD134+ on CD4+ T cells in PF can serve as a potential marker for TP diagnosis.

Cutaneous tuberculosis in the pediatric population: A review

Importance

Tuberculosis (TB) is a significant health concern, affecting over 1.5 million people annually worldwide, with the incidence increasing in the United States from 2020 to 2021. The pediatric population is particularly vulnerable to TB. Extrapulmonary manifestations of TB include cutaneous tuberculosis (CTB).

Observations

There are 8 forms of CTB. Lupus vulgaris (LV) is the second most common form of pediatric CTB which presents nontender plaques or nodules with ulceration that progress to well-defined, scaly plaques. Tuberculous chancre results from exogenous inoculation and lesions contain large amounts of acid-fast bacilli (AFB). Clinically, tuberculous chancre presents as erythematous papules which form firm nontender ulcers. Tuberculosis verrucose cutis (TVC) presents as small papules surrounded by inflammation that develops into a wart-like lesion. Periorificial lesions are rare and present as painful ulcers in the oral or perineal regions. Scrofuloderma is the most common form of pediatric CTB and presents as nodules that ulcerate, forming purulent sinus tracts. Tuberculosis miliaris cutis disseminate presents as widespread papules and crusted vesicles. Metastatic abscesses present as multiple nodules that may ulcerate or form draining sinus tracts. Lastly, tuberculid forms include lichen scrofulosorum (LS), which presents as lichenoid papules which may form plaques and scale, and papulonecrotic tuberculid, which presents as necrotic papules. All forms of cutaneous tuberculosis can be treated with the standard 6-month, four-drug anti-tuberculosis treatment (ATT). Some cases of CTB may require debriding and surgical management in addition to ATT.

Conclusions and Relevance

Determining the type of CTB can be challenging clinically. Histopathology is needed to make the diagnosis. Chest x-ray and a review of systems should be obtained for CTB patients to determine if there are other extrapulmonary manifestations of TB. All types are treated with 6 months of ATT.

Delay analysis of pulmonary tuberculosis in the eastern coastal county of China from 2010 to 2021: evidence from two surveillance systems

Background

Tuberculosis (TB) remains a major public health challenge. However, indicators of delays in assessing effective TB prevention and control and its influencing factors have not been investigated in the eastern coastal county of China.

Methods

All notified pulmonary tuberculosis (PTB) cases in the Fenghua District, China were collected between 2010 and 2021 from the available TB information management system. Comparison of delays involving patient, health system, and total delays among local and migrant cases. Additionally, in correlation with available Basic Public Health Service Project system, we performed univariate and multivariate logistic regression analyses identified the influencing factors associated with patient and total delays in patients aged >60 years.

Results

In total, 3,442 PTB cases were notified, including 1,725 local and 1,717 migrant patients, with a male-to-female ratio of 2.13:1. Median patient and total delays of local TB patients were longer than those for migrant patients; the median health system delay did not show any significant difference. For patient delay among the older adult, female (cOR: 1.93, 95% CI: 1.07-3.48), educational level of elementary school and middle school (cOR: 0.23, 95% CI: 0.06-0.84) had a statistical difference from univariable analysis; however, patients without diabetes showed a higher delay for multiple-factor analysis (aOR: 2.12, 95% CI: 1.02-4.41). Furthermore, only the education level of elementary school and middle school presented a low total delay for both univariate (cOR: 0.22, 95% CI: 0.06-0.82) and multivariate analysis (aOR: 0.21, 95% CI: 0.05-0.83) in the older patients.

Conclusion

The delay of TB cases among migrants was lower than the local population in the Fenghua District, which may be related to the "healthy migrant effect". It highlights that women, illiterate people, and people without diabetes are key groups for reducing delays among older adults. Health awareness should focus on these target populations, providing accessible health services, and reducing the time from symptom onset to diagnosis.

Variation in Treatment of Pediatric Tuberculosis Infection in Different Provider Settings

OBJECTIVES

To evaluate implementation of rifamycin-based regimens (RBR) for pediatric tuberculosis infection (TBI) treatment among 3 provider settings in a high-incidence county.

STUDY DESIGN

A multicenter, retrospective observational study was performed across 3 sites in Los Angeles County: an academic center (AC), a general pediatrics federally qualified health center (FQHC), and department of public health (DPH) tuberculosis clinics. Patients initiated on TBI treatment age 1 months to 17 years between 2018 and 2020 were included. RBRs were defined as regimens: 3 months of weekly rifapentine and isoniazid, 4 months of daily rifampin, and 3 months of daily isoniazid and rifampin.

RESULTS

We included 424 patients: 51 from AC, 327 from DPH, and 46 from FQHC. RBR use nearly doubled during the study period (from 43% in 2018 to 82% in 2020; P < .001). FQHC had the shortest time to chest radiograph and treatment initiation; however, AC and DPH were 4 times as likely to prescribe an RBR compared to FQHC (95% CI, 2.1-7.8). AC and DPH had similar completion rates (74%) and were 2.6 times as likely to complete treatment compared to FQHC (95% CI, 1.4-4.9).

CONCLUSIONS

The use of RBRs for pediatric TBI varies significantly by clinical setting but is improving over time. Strategies are needed to improve RBR uptake, standardize care, and increase treatment completion, particularly among general pediatricians.

Latent Tuberculosis Infection Treatment Practices in Two Large Integrated Health Systems in California, 2009-2018

Background

Treatment of latent tuberculosis infection (LTBI) is highly effective at preventing active tuberculosis (TB) disease. Understanding LTBI treatment practices in US health system settings is critical to identify opportunities to improve treatment prescription, initiation, and completion, and thus to prevent TB disease.

Methods

We assessed LTBI treatment practices among a cohort of adults after their first positive LTBI test (tuberculin skin test [TST] or interferon gamma release assay [IGRA]) between 2009 and 2018 at 2 large integrated health systems in California. We described the prescription, initiation, and completion of LTBI treatment (isoniazid [INH], rifampin, and rifamycin-INH short-course combinations) by demographic and clinical characteristics. We used multivariable robust Poisson regression to examine factors that were independently associated with treatment prescription and completion.

Results

Among 79 302 individuals with a positive LTBI test, 33.0% were prescribed LTBI treatment, 28.3% initiated treatment, and 18.5% completed treatment. Most individuals were prescribed INH (82.0%), but treatment completion was higher among those prescribed rifamycin-INH short-course combinations (69.6% for INH + rifapentine and 70.3% for INH + rifampin) compared with those prescribed INH (56.3%) or rifampin (56.6%). In adjusted analyses, treatment prescription and completion were associated with older age, female sex, more comorbidities, immunosuppression, not being born in a high-TB incidence country, and testing positive with IGRA vs TST.

Conclusions

LTBI treatment is underutilized, requiring tailored interventions to support treatment prescription and completion for patients with LTBI.

The Latent Tuberculosis Infection Cascade of Care During The COVID-19 Pandemic Response in a Mid-Sized US City

Background

The COVID-19 pandemic response may unintentionally disrupt multiple public health services, including tuberculosis control programs. We aimed to assess differences in the cascade of care for latent tuberculosis infection (LTBI) in a Midwest U.S. city during the COVID-19 pandemic response.

Methods

We conducted a retrospective cohort study of adult patients who presented for LTBI evaluation at the Hamilton County Public Health Tuberculosis Clinic in Ohio between 2019 and 2020. The pre-COVID-19 response period was defined as 01/2019 to 02/2020, and the COVID-19 pandemic response period (first wave) was defined as 04/2020 to 12/2020. We reviewed electronic medical records to extract sociodemographic information, medical history, follow-up and treatment data to define steps within the LTBI cascade of care. Logistic regressions were used to assess factors associated with LTBI treatment acceptance and completion, adjusted by potential confounders and COVID-19 period.

Results

Data from 312 patients were included. There was a significant decrease in the number of monthly LTBI referrals (median, 18 vs. 8, p = 0.02) and LTBI evaluations (median, 17.5 vs. 7, p < 0.01) during the first wave of COVID-19. The proportion for whom immigration was listed as the indication for LTBI testing also declined (30% vs. 9%; p < 0.01) during COVID-19. More LTBI diagnoses were based on interferon-gamma release assay (IGRA; 30% vs. 49%; p < 0.01) during the COVID-19 response period. The proportion of people in the clinic for whom treatment for LTBI was recommended was similar before and during COVID-19 (76% vs. 81%, p = 0.41), as was LTBI treatment acceptance rates (56% vs. 64%, p = 0.28), and completion rates (65% vs. 63%, p = 0.85). In multivariate analysis, LTBI treatment acceptance was associated with Hispanic ethnicity, younger age, male sex, IGRA being used for diagnosis, and non-healthcare occupation, independent of COVID-19 period. LTBI treatment completion was associated with taking a rifamycin-containing regimen, independent of COVID-19 period.

Conclusion

We observed a significant decline in the number of monthly LTBI referrals and evaluations during the first wave of COVID-19, revealing an unintended negative impact of the COVID-19 response in our region. However, LTBI treatment acceptance and completion rates were not affected during COVID-19.

Advances in TB testing

Globally, tuberculosis (TB) was the leading cause of death from a single infectious agent until the coronavirus (COVID-19) pandemic. In 2020, an estimated 10 million people fell ill with TB and a total of 1.5 million people died from the disease. About one-quarter of the global population, almost two billion people, is estimated to be latently infected with Mycobacterium tuberculosis (MTB). Although latent TB infection (LTBI) is asymptomatic and noncontagious, about 5-10% of LTBI patients have a lifetime risk of progression to active TB. The diagnosis and treatment of active cases are extremely vital for TB control programs. However, achieving the End TB goal of 2035 without the ability to identify and treat the pool of latently infected individuals will be a big challenge. To do so, improved technology to provide more accurate diagnostic tools and accessibility are crucial. Therefore, this chapter covers the current WHO-endorsed tests and advances in diagnostic and screening tests for active and latent TB.

Latent Tuberculosis Treatment among Hard-to-Reach Ethiopian Immigrants: Nurse-Managed Directly Observed versus Self-Administered Isoniazid Therapy

BACKGROUND

The treatment of latent tuberculosis infection (LTBI) among high-risk populations is an essential component of Tuberculosis (TB) elimination. However, non-compliance with LTBI treatment remains a major obstacle hindering TB elimination efforts. We have previously reported high treatment compliance with nurse-managed, twice-weekly, directly observed Isoniazid treatment (DOT) for LTBI among hard-to-reach Ethiopian immigrants (EI's).

OBJECTIVES

to compare rate of completion of treatment, cost, and major adverse drug events with daily self-administered Isoniazid treatment (SAT) to nurse-managed Isoniazid DOT among hard-to-reach EIs.

MATERIALS AND METHODS

We conducted a retrospective study and compared self-administered LTBI treatment outcomes among EIs housed in reception centers during 2008-2012 to EIs treated with DOT.

RESULTS

Overall, 455 EIs were included (231 DOT, 224 SAT) in the study. We found no significant difference in treatment completion rates between the two groups (93.0% DOT vs. 87.9% SAT, p = 0.08). However, cases of grade III, drug-induced hepatitis were significantly fewer and treatment costs were significantly lower with the nurse-managed DOT compared with SAT (0% vs. 2.2%, p = 0.028, 363 vs. 521 United States Dollars, p < 0.001, respectively).

CONCLUSIONS

Nurse-managed, twice-weekly DOT among hard-to-reach EIs housed in reception centers had less severe drug-related adverse events and reduced treatment cost compared with daily isoniazid SAT, yet we found no significant difference in treatment completion between the two strategies in this population.

Demographic Control Measure Implications of Tuberculosis Infection for Migrant Workers across Taiwan Regions

A sharp increase in migrant workers has raised concerns for TB epidemics, yet optimal TB control strategies remain unclear in Taiwan regions. This study assessed intervention efforts on reducing tuberculosis (TB) infection among migrant workers. We performed large-scale data analyses and used them to develop a control-based migrant worker-associated susceptible-latently infected-infectious-recovered (SLTR) model. We used the SLTR model to assess potential intervention strategies such as social distancing, early screening, and directly observed treatment, short-course (DOTS) for TB transmission among migrant workers and locals in three major hotspot cities from 2018 to 2023. We showed that social distancing was the best single strategy, while the best dual measure was social distancing coupled with early screening. However, the effectiveness of the triple strategy was marginally (1-3%) better than that of the dual measure. Our study provides a mechanistic framework to facilitate understanding of TB transmission dynamics between locals and migrant workers and to recommend better prevention strategies in anticipation of achieving WHO's milestones by the next decade. Our work has implications for migrant worker-associated TB infection prevention on a global scale and provides a knowledge base for exploring how outcomes can be best implemented by alternative control measure approaches.

US Postarrival Evaluation of Immigrant and Refugee Children with Latent Tuberculosis Infection Diagnosed Overseas, 2007-2019

OBJECTIVE

To assess outcomes from the US postarrival evaluation of newly arrived immigrant and refugee children aged 2-14 years who were diagnosed with latent tuberculosis infection (LTBI) during a required overseas medical examination.

STUDY DESIGN

We compared overseas and US interferon-γ release assay (IGRA)/tuberculin skin test (TST) results and LTBI diagnosis; assessed postarrival LTBI treatment initiation and completion; and evaluated the impact of switching from TST to IGRA to detect Mycobacterium tuberculosis infection overseas.

RESULTS

In total, 73 014 children were diagnosed with LTBI overseas and arrived in the US during 2007-2019. In the US, 45 939 (62.9%) completed, and 1985 (2.7%) initiated but did not complete a postarrival evaluation. Among these 47 924 children, 30 360 (63.4%) were retested for M tuberculosis infection. For 17 996 children with a positive overseas TST, 73.8% were negative when retested by IGRA. For 1051 children with a positive overseas IGRA, 58.0% were negative when retested by IGRA. Overall, among children who completed a postarrival evaluation, 18 544 (40.4%) were evaluated as having no evidence of TB infection, and 25 919 (56.4%) had their overseas LTBI diagnosis confirmed. Among the latter, 17 229 (66.5%) initiated and 9185 (35.4%) completed LTBI treatment.

CONCLUSIONS

Requiring IGRA testing overseas could more effectively identify children who will benefit from LTBI treatment. However, IGRA reversions may occur, highlighting the need for individualized assessment for risk of infection, progression, and poor outcome when making diagnostic and treatment decisions. Strategies are needed to increase the proportions receiving a postarrival evaluation and completing LTBI treatment.

Prevalence trends of latent tuberculosis infection at the global, regional, and country levels from 1990-2019

OBJECTIVES

To track the prevalence trends of latent tuberculosis infection (LTBI) at the global, regional, and national levels.

METHODS

Data on the prevalence of LTBI were extracted from the Global Burden of Disease database. The average annual percent change (AAPC) was estimated by joinpoint regression and was used to evaluate the epidemic of the disease.

RESULTS

Globally, the prevalence rate of LTBI decreased from 30.66% in 1990 to 23.67% in 2019, with an AAPC of -0.9%. The prevalence rate of LTBI varied from 5.02% (Jordan) to 48.35% (Uganda) in 1990 and from 2.51% (Jordan) to 43.75% (Vietnam) in 2019 at the country level. The prevalence decreased in all the six World Health Organization (WHO) regions and in most countries, with the AAPC ranging from -0.5% in the Western Pacific Region to -2.1% in the European Region and from -4.3% (Bhutan) to -0.1% (Malaysia, Myanmar, South Africa, Tokelau, and Vietnam), respectively. Disparities were also observed among different sex and age groups.

CONCLUSION

The prevalence of LTBI decreased slightly worldwide in the last three decades, but the decrease is slow and not sufficient to meet the targets of WHO tuberculosis elimination. Much more effort and progress should be made in order to decrease the prevalence of LTBI.

Optimal Detection of Latent Mycobacterium tuberculosis Infection by Combined Heparin-Binding Hemagglutinin (HBHA) and Early Secreted Antigenic Target 6 (ESAT-6) Whole-Blood Interferon Gamma Release Assays

Optimal detection of latent tuberculosis (TB) infection (LTBI) remains a challenge, although it is essential to reach the goal of TB elimination. Our objective was to develop and clinically evaluate a user-friendly, 24-h, whole-blood (WB) interferon gamma (IFN-γ) release assay (IGRA) improving the detection of LTBI, compared to available tests. One milliliter of blood was divided into four aliquots and in vitro stimulated for 24 h with two different stage-specific mycobacterial antigens, i.e., heparin-binding hemagglutinin (HBHA) and early secreted antigenic target 6 (ESAT-6), a latency-associated antigen and a bacterial replication-related antigen, respectively, in addition to positive and negative controls. Clinical evaluation was performed on two independent cohorts of carefully selected subjects, i.e., a training cohort of 83 individuals and a validation cohort of 69 individuals. Both cohorts comprised LTBI subjects (asymptomatic people with a positive tuberculin skin test result and potential exposure to TB index cases), patients with active TB (aTB), and noninfected controls. The sensitivity and specificity of the WB-HBHA-IGRA to identify LTBI subjects among asymptomatic individuals were 93%. Combining the results in response to HBHA and ESAT-6 allowed us to identify LTBI subgroups. One group, with IFN-γ responses to HBHA only, was easily differentiated from patients with aTB. The other group, responding to both antigens like the aTB group, is likely at risk to reactivate the infection and should be prioritized for prophylactic anti-TB treatment. The combined WB-IGRA may be offered to clinicians for the selection of LTBI subjects to benefit from prophylactic treatment.

Reporting of Latent TB Infection Among Non-US-Born Persons Adjusting Their Immigration Status to Permanent Residents: An Opportunity to Enhance TB Prevention

From October 15, 2019, to June 12, 2020, Public Health-Seattle & King County conducted phone outreach to individuals referred to the public health department by civil surgeons. The objective was to explore common barriers and facilitators to treatment of latent tuberculosis infection (LTBI) among this population. Civil surgeons are mandated to report cases of LTBI to the state or local health department. Outreach revealed a wide variation in patient understanding of LTBI and provider practices around discussing LTBI and recommending LTBI treatment. The results of this small-scale study can inform public health strategies to engage with civil surgeons and their patients to both improve reporting practices and increase rates of LTBI treatment completion in patients born in high TB burden countries. In addition, these findings provide insight into what challenges and opportunities may emerge when health jurisdictions mandate LTBI reporting at a state or county level.

LncRNA CCAT1 is overexpressed in tuberculosis patients and predicts their survival

INTRODUCTION

LncRNA CCAT1 promotes inflammatory responses, which contribute to tuberculosis. Therefore, CCAT1 may participate in tuberculosis. Therefore, we analyzed the involvement of CCAT1 in tuberculosis.

METHODS

Plasma samples were donated by a total of 200 patients with newly developed tuberculosis (N-TB), 102 patients with recurrent tuberculosis (R-TB), and 102 healthy controls on the day of admission. Plasma samples were also collected from N-TB and R-TB patients every month after the initiation of treatment for a total of 6 months. CCAT1 expression in these samples was detected by quantitative reverse transcription polymerase chain reaction. Levels of IFN-γ, IL-1β, iNOS, TNF-α, and IL-10 in plasma were determined by enzyme-linked immunosorbent assay. N-TB and R-TB patients were monitored for 2 months to analyze their survival.

RESULTS

On the day of admission, the highest levels of CCAT1, IFN-γ, IL-1β, iNOS, and TNF-α were detected in N-TB patients, followed by R-TB patients and controls, while the lowest levels of plasma IL-10 were detected in N-TB patients, followed by R-TB patients and controls. Across R-TB and N-TB patients, CCAT1 was inversely correlated with IL-10 but not closely correlated with other inflammatory factors. During the treatment, plasma CCAT1 levels decreased in both N-TB and R-TB patients. High CCAT1 levels were closely correlated with high mortality rates of both N-TB and R-TB patients.

CONCLUSION

CCAT1 is overexpressed in tuberculosis patients and predicts their survival. Its function in tuberculosis may be related to IL-10.

Structural identifiability analysis of age-structured PDE epidemic models

Computational and mathematical models rely heavily on estimated parameter values for model development. Identifiability analysis determines how well the parameters of a model can be estimated from experimental data. Identifiability analysis is crucial for interpreting and determining confidence in model parameter values and to provide biologically relevant predictions. Structural identifiability analysis, in which one assumes data to be noiseless and arbitrarily fine-grained, has been extensively studied in the context of ordinary differential equation (ODE) models, but has not yet been widely explored for age-structured partial differential equation (PDE) models. These models present additional difficulties due to increased number of variables and partial derivatives as well as the presence of boundary conditions. In this work, we establish a pipeline for structural identifiability analysis of age-structured PDE models using a differential algebra framework and derive identifiability results for specific age-structured models. We use epidemic models to demonstrate this framework because of their wide-spread use in many different diseases and for the corresponding parallel work previously done for ODEs. In our application of the identifiability analysis pipeline, we focus on a Susceptible-Exposed-Infected model for which we compare identifiability results for a PDE and corresponding ODE system and explore effects of age-dependent parameters on identifiability. We also show how practical identifiability analysis can be applied in this example.

The Health and Economic Benefits of Tests That Predict Future Progression to Tuberculosis Disease

BACKGROUND

Effective targeting of latent tuberculosis infection (LTBI) treatment requires identifying those most likely to progress to tuberculosis (TB). We estimated the potential health and economic benefits of diagnostics with improved discrimination for LTBI that will progress to TB.

METHODS

A base case scenario represented current LTBI testing and treatment services in the United States in 2020, with diagnosis via. interferon-gamma release assay (IGRA). Alternative scenarios represented tests with higher positive predictive value (PPV) for future TB but similar price to IGRA, and scenarios that additionally assumed higher treatment initiation and completion. We predicted outcomes using multiple transmission-dynamic models calibrated to different geographic areas and estimated costs from a societal perspective.

RESULTS

In 2020, 2.1% (range across model results: 1.1%-3.4%) of individuals with LTBI were predicted to develop TB in their remaining lifetime. For IGRA, we estimated the PPV for future TB as 1.3% (0.6%-1.8%). Relative to IGRA, we estimated a test with 10% PPV would reduce treatment volume by 87% (82%-94%), reduce incremental costs by 30% (15%-52%), and increase quality-adjusted life years by 3% (2%-6%). Cost reductions and health improvements were substantially larger for scenarios in which higher PPV for future TB was associated with greater initiation and completion of treatment.

CONCLUSIONS

We estimated that tests with better predictive performance would substantially reduce the number of individuals treated to prevent TB but would have a modest impact on incremental costs and health impact of TB prevention services, unless accompanied by greater treatment acceptance and completion.

Latent Tuberculosis Infection Treatment Outcomes in an At-Risk Underserved Population in Rhode Island

OBJECTIVES

Within the United States (US), significant racial and ethnic disparities exist in the rates of latent TB infection (LTBI) and active TB disease. A disproportionate number of TB disease cases result from untreated LTBI among individuals born outside the US. This study evaluates LTBI treatment outcomes among an underserved, at-risk population in Rhode Island.

METHODS

A quantitative retrospective chart review of adult patients with a positive screening test assessed LTBI care cascade outcomes including referral, treatment initiation, and completion.

RESULTS

Seventy-four percent of patients found to have positive screening TB tests were born outside of the US; 80% identified as Hispanic or Black and 45% spoke a preferred language other than English. Twenty-one percent of potential candidates for LTBI treatment initiated treatment.

CONCLUSIONS

Major gaps were identified in referral success and treatment initiation. Expanding LTBI treatment access into primary care settings could be a solution to improve outcomes and decrease health inequities among at-risk communities.

Emergency department screening for latent tuberculosis infection

OBJECTIVE

Approximately 12.4 million people in the U.S. have latent tuberculosis infection (LTBI), 73% of whom are non-U.S. born. Identification and treatment of LTBI are essential for tuberculosis eradication. We evaluated an emergency department (ED) - based LTBI screening and linkage to care program.

METHODS

We queried electronic records of a clinical prevention program located in a Midwestern, urban, academic ED that serves as the region's safety-net hospital. Program staff approached non-U.S. born ED patients from TB endemic areas. Patients received QuantiFERON-TB Gold Plus (QFT) blood testing and, if positive, were referred to treatment. The primary outcome was the proportion of tested patients newly diagnosed with LTBI. We secondarily report the number of patients linked to care who initiated LTBI treatment.

RESULTS

The program approached 33 patients, of whom 24 (72.7%) were eligible, and 23 (95.8%) were tested. The majority were male (13, 56.5%), median age was 33 years (IQR 27-45), and 13 (56.5%) were from Latin America. Three patients (13.0%, 95% CI 0.03-0.35) were newly diagnosed with LTBI and linked to care; two (66.7%) started LTBI treatment.

CONCLUSIONS

In this first report of an ED-based LTBI screening program implemented in a region with low TB prevalence, over 10% of high-risk ED patients tested positive for LTBI and were linked to treatment. Screening populations at risk for LTBI in EDs and linking them to public health treatment services should be prioritized in order to achieve TB elimination in the U.S.

Challenges in LTBI care in the United States identified using a nationwide TB medical consultation database

BACKGROUND

Identifying and treating individuals with latent TB infection (LTBI) represents a critical and challenging component of national TB elimination. Medical consultations by the Centers for Disease Control and Prevention (CDC) funded TB Centers of Excellence (COEs) are an important resource for healthcare professionals (HCPs) caring for individuals with LTBI. This study aimed to identify the most common clinical concerns regarding LTBI care and to describe epidemiologic and clinical features of patients discussed in these consultations.

METHODS

This mixed-methods study randomly sampled 125 consultation inquiries related to LTBI from the COEs' medical consultation database in 2018. Text from consultation records were reviewed and coded to identify reasons for the inquiries and common epidemiologic and clinical patient characteristics.

RESULTS

The most common topics of inquiry for consultation included accurate LTBI diagnosis (36%), management of LTBI treatment-related issues (22%), and choice of appropriate LTBI treatment regimen (17%). Patients for whom consultations were requested commonly had another medical condition (34%), were non-U.S. born (31%), were children (25%), and had a history of travel to TB-endemic areas (18%).

CONCLUSION

Our findings emphasize the challenge of managing patients with either suspected or confirmed LTBI, highlighting the need for ongoing medical consultation support for nuanced clinical and epidemiologic scenarios.

Prevalence of Latent TB and Effectiveness of BCG Vaccination Against Latent Tuberculosis: An Observational Study

OBJECTIVES

This study aimed to determine the prevalence of latent tuberculosis infection (LTBI) in immigrant children and adolescents (aged 0-17 years) living or recently arriving in Sweden. It also aimed to estimate the effectiveness of Bacillus Calmette-Guérin (BCG) against LTBI in immigrant children coming to Sweden from high-incidence countries, most of them being asylum seekers. LTBI was defined as a positive Quantiferon or a tuberculin skin test (TST) of ≥ 10 mm in small children from whom it was difficult to obtain 3 mL of blood.

DESIGN

A typical BCG scar was used as a substitute for written documentation of BCG vaccination. The study comprised 1,404 immigrants aged 0-17 years. The arms and legs of all of them were inspected for a BCG scar, and Quantiferon or TST was performed. The study was a retrospective, observational, comparative cohort study.

RESULTS

LTBI was found in 123 of 1,011 (12%) children with a BCG scar and in 116 of 393 (29.5%) without a BCG scar, giving an estimated vaccine effectiveness of 59%.

CONCLUSIONS

LTBI was common among the immigrant children (17%). LTBI can progress to active TB and then spread in the immigrant population and to the general population if all immigrant arrivals are not tested and given prophylactic treatment if they have LTBI. The BCG vaccine was found to have a significant effect on LTBI (59%).

Inhalable solid lipid nanoparticles for intracellular tuberculosis infection therapy: macrophage-targeting and pH-sensitive properties

Mycobacterium tuberculosis (MTB) is one of the most threatening pathogens for its latent infection in macrophages. The intracellular MTB isolated itself from drugs and could spread via macrophages. Therefore, a mannose-modified macrophage-targeting solid lipid nanoparticle, MAN-IC-SLN, loading the pH-sensitive prodrug of isoniazid (INH), was designed to treat the latent tuberculosis infection. The surface of SLNs was modified by a synthesized 6-octadecylimino-hexane-1,2,3,4,5-pentanol (MAN-SA) to target macrophages, and the modified SLNs showed a higher cell uptake in macrophages (97.2%) than unmodified SLNs (42.4%). The prodrug, isonicotinic acid octylidene-hydrazide (INH-CHO), was synthesized to achieve the pH-sensitive release of INH in macrophages. The INH-CHO-loaded SLNs exhibited a pH-sensitive release profile and accomplished a higher accumulated release in pH 5.5 media (82.63 ± 2.12%) compared with the release in pH 7.4 media (58.83 ± 3.84%). Mycobacterium smegmatis was used as a substitute for MTB, and the MAN-IC-SLNs showed a fourfold increase of intracellular antibiotic efficacy and enhanced macrophage uptake because of the pH-sensitive degradation of INH-CHO and MAN-SA in SLNs, respectively. For the in vivo antibiotic efficacy test, the SLNs group displayed an 83% decrease of the colony-forming unit while the free INH group only showed a 60% decrease. The study demonstrates that macrophage targeting and pH-sensitive SLNs can be used as a promising platform for the latent tuberculosis infection. Graphical Abstract Table of contents: Macrophage-targeting and pH-sensitive solid lipid nanoparticles (SLN) were administrated to the lung via nebulization. Macrophage targeting was achieved by appropriate particle size and surface mannose modification with synthesized MAN-SA. After being swallowed by macrophages, the prodrug, Isonicotinic acid octylidene-hydrazide (INH-CHO), quickly released isoniazid, which was triggered by the intracellular acid environment. The SLNs exhibited higher intracellular antibiotic efficacy due to their macrophage-targeting and pH-sensitive properties.

Distribution of molecular strains of Mycobacterium tuberculosis in an intermediate burden Asia Pacific city

Hong Kong is an intermediate tuberculosis (TB) burden city in Asia Pacific with slow decline of case notification in the last decade. By 24-loci mycobacterial interspersed repetitive units – variable number of tandem repeats genotyping, we examined 534 Mycobacterium tuberculosis isolates collected from culture-positive hospitalised TB patients in a 1.7 million population geographic region in the city. Overall, 286 (75%) were classified as Beijing genotype, of which 216 (76%) and 59 (21%) belonged to modern and ancient sub-lineage, respectively. Only two cases were genetically clustered while spatial clustering was absent. Male gender, permanent residency in Hong Kong and born in Hong Kong or Mainland China were associated with Beijing genotype. The high prevalence of Beijing modern lineage was similar to that in East Asia, which reflected the pattern resulting from population migration. The paucity of clustering suggested that reactivation accounted for most of the TB disease cases, which was and echoed by observation that half were 60 years old or above, and the presence of co-morbid medical conditions. The predominance of reactivation TB cases in intermediate burden localities implies that the detection and control of latent TB infection would be the major challenge in achieving TB elimination.

Evaluation of the treatment efficacy of systemic care combined with thymopentin and 2HRZE/4HR for primary tuberculosis

OBJECTIVE

To investigate the efficacy of systemic care combined with thymopentin and 2HRZE/4HR in the treatment of primary tuberculosis.

METHODS

The clinical data of 93 patients with primary tuberculosis were retrospectively collected and divided into two groups based on the intervention method. Group A (n=46) was treated only with 2HRZE/4HR, and group B (n=47) was treated with the 2HRZE/4HR combined with thymopentin. Meanwhile, both groups received systematic care. The lesion absorption rate, sputum conversion rate (SCR), T lymphocyte subpopulation count, immunoglobulin level, lung function index, changes in sputum supernatant levels of cytokines before and after treatment, and the occurrence of adverse reactions were compared.

RESULTS

Group B exhibited higher complete absorption rate of foci and lower basic absorption rate than group A (P < 0.05). The SCRs of group B after 2, 4 and 6 months of intervention were higher than those of group A (P < 0.05). Compared with group A, group B had lower CD8⁺ level and higher CD4⁺ and CD3⁺ levels (P < 0.05). Group B also had higher levels of IgA, IgG, and IgM than group A after intervention (P < 0.05). Group B had higher levels of FEV1, PEF, and FVC than group A after intervention (P < 0.05). In contrast to group A, group B had lower IL-4 levels and higher TNF-γ levels (P < 0.05). The incidence rate of adverse events in group B was not significantly different from that in group A (P > 0.05).

CONCLUSION

Systemic care combined with 2HRZE/4HR was effective for treatment of primary tuberculosis, which is beneficial for improving the immunity, SCR, and the inflammatory status, with low incidence of adverse events and a high safety level.

Performance of an Advanced Interferon-Gamma Release Assay for Mycobacterium tuberculosis Detection

BACKGROUND

The LIAISON® QuantiFERON®-TB Gold Plus (QFT-Plus) assay, a fully automated chemiluminescence immunoassay (CLIA) system, has recently received FDA approval for the detection of interferon-γ (IFN-γ) on the LIAISON XL analyzer. Here, we evaluated the diagnostic performance of the LIAISON's CLIA method in comparison to the widely used ELISA method using the Qiagen QuantiFERON-TB Gold Plus Blood Collection Tubes.

METHODS

Heparinized blood samples from 329 participants were categorized into 3 cohorts, including 15 with confirmed tuberculosis (TB) (active TB cohort), 129 non-TB (low-risk cohort), and 185 potential TB (mixed risk cohort). Samples were analyzed with both assays and results were interpreted according to the manufacturers' criteria.

RESULTS

The LIAISON CLIA assay showed an overall agreement with the Qiagen ELISA assay in 13/14 (92.8%) samples among the active cohort, 93/95 (97.9%) among the low-risk cohort, with a Cohen's kappa value of 0.76 and 0.74, respectively. Test results for 185 mixed risk cohort participants showed 97.8% agreement between the LIAISON and the Qiagen, with 17 positive, 163 negative, and 1 indeterminate. Four samples were discrepant; 3 of these were negative on the ELISA but positive on the CLIA assay.

CONCLUSION

Overall, the results were comparable (>92% agreement) in our study cohorts. In addition, our mixed risk cohort results showed an excellent agreement of 0.88 (Cohen's kappa value) between the 2 assays. These findings suggest that the automated LIAISON QFT-Plus assay has a comparable diagnostic performance to the Qiagen assay and can be used for latent TB infection (LTBI) diagnosis.

Global burden of tuberculosis attributable to cancer in 2019: Global, regional, and national estimates

BACKGROUND

Cancer is an independent risk factor for tuberculosis (TB). The global burden of incident TB attributable to cancer has never been explored. We aimed to evaluate the cancer-attributable burden of TB.

METHODS

We estimated the population attributable fraction (PAF) by Levin's formula. The cancer prevalence rates were derived from the Institute for Health Metrics and Evaluation. The relative risk of TB in cancer patients was estimated by using the National Health Insurance Research Database in Taiwan. The global burden of incidence TB attributable to cancer was the weighted sum of PAFs multiplied by the incidence of TB retrieved from the World Health Organization.

RESULTS

Worldwide, the total of incident TB cases attributable to cancer was 115,478 cases with a 95% confidence interval (CI), 110,482-123,007, in 2019. The global PAF of TB due to cancer was 1.85% (95% CI, 1.77-1.97%). The three countries with the highest PAFs were Greenland (7.77%), Canada (7.75%), and the United States of America (6.79%), while the three countries with the highest attributable TB cases due to cancer were China (25,240), India (21,629), and Indonesia (13,917). Cancer of respiratory system contributed to 60,257 of TB cases.

CONCLUSIONS

This study comprehensively explored the impact of cancer on the global burden of TB. Efforts to reduce cancer risk, delay the occurrence of cancer, or treat latent TB infection in the cancer population could potentially reduce the burden of TB and rely on formulating integrated strategies.

Self-Reported Engagement in Care among U.S. Residents with Latent Tuberculosis Infection - 2011-2012

RATIONALE

A central strategy of tuberculosis (TB) control in the United States is reducing the burden of latent TB infection (LTBI) through targeted testing and treatment of persons with untreated LTBI.

OBJECTIVES

The objective of the study was to provide estimates of and risk factors for engagement in LTBI care in the overall U.S. population and among specific risk groups.

METHODS

We used nationally representative data from 7,080 participants in the 2011-2012 National Health and Nutrition Examination Survey. Engagement in LTBI care was assessed by estimating the proportion with a history of testing, diagnosis, treatment initiation and treatment completion. Weighted methods were used to account for the complex survey design and to derive national estimates.

RESULTS

Only 1.4 million (10%) of an estimated 14.0 million individuals with LTBI had previously completed treatment. Of the 12.6 million who did not complete LTBI treatment, 3.7 million (29%) had never been tested and 7.2 million (57%) received testing but had no history of diagnosis. High-risk groups showed low levels of engagement, including TB contacts and persons born outside the United States.

CONCLUSIONS

There is a reservoir of more than 12 million individuals in the U.S. who may be at risk for progression to TB disease and potential transmission. TB control programs and community providers should consider focused efforts to increase testing, diagnosis, and treatment for LTBI.

Guidelines on controlling latent tuberculosis infection to support tuberculosis elimination

Objectives

Latent TB infection (LTBI) affects 25% of the world’s population. As long as this reservoir exists, the elimination of TB will not be feasible. The Assembly of the World Health Organization adopted the “Global End TB” strategy for the elimination of TB in 2014. The objective of this review is to present strategies for risk groups that are candidates for the detection and treatment of LTBI.

Material and method

There is sufficient evidence of screening in: immunocompromised people (HIV-infected, biological therapies, alternative renal therapy, organ transplantation), recent immigrants, inmates in prison, people injecting drugs and homeless people, and workers from at-risk settings. Tests to diagnose LTBI include tuberculin skin test (TST) and gamma release assay interferon (IGRA). There is no reference test and the choice of one or the other will depend on logistical considerations, such as avoiding injection (TST) or not needing a second visit (IGRA). Treatment of LTBI is based on the use of isoniazide and rifampicin in short period of 3 or 4 months, using associations of rifampicin and isoniazide or rifampicin alone.

Discussion

Given the estimated high prevalence of LTBI, renewed efforts are required to reduce the number of people with LTBI that includes a registration and monitoring system to observer progress, increased testing, and the use of short treatment guidelines.