Screening for Latent Tuberculosis Infection in People Living with HIV: TUBHIVIT Project, a Multicenter Italian Study.

BACKGROUND: The coexistence of HIV infection and latent tuberculosis infection (LTBI) presents a significant public health concern due to the increased risk of tuberculosis (TB) reactivation and progression to active disease. The multicenter observational cohort study, TUBHIVIT, conducted in Italy from 2017 to 2023, aimed to assess the prevalence of LTBI among people living with HIV (PLHIV) and their outcomes following LTBI screening and therapy initiation. METHODS: We performed a prospective study in five referral centers for HIV care in Italy. PLHIV who consented Tto participate underwent QuantiFERON-TB Gold Plus and clinical, microbiological, and radiological assessments to exclude subclinical tuberculosis, as opportune. PLHIV diagnosed with LTBI who started chemoprophylaxis were followed until the end of therapy. RESULTS: A total of 1105 PLHIV were screened for LTBI using the QuantiFERON-TB Gold Plus test, revealing a prevalence of 3.4% of positive results (38/1105). Non-Italy-born individuals exhibited a significantly higher likelihood of testing positive. Thirty-one were diagnosed with LTBI, 1 showed active subclinical TB, and 6 were lost to follow-up before discriminating between latent and active TB. Among the PLHIV diagnosed with LTBI, 83.9% (26/31) started chemoprophylaxis. Most individuals received 6-9 months of isoniazid-based therapy. Of the 26 PLHIV commencing chemoprophylaxis, 18 (69.2%) completed the therapy, while 3 discontinued it and 5 were still on treatment at the time of the analysis. Adverse events were observed in two cases, while in one case the patient refused to continue the treatment.

Incidence and risk factors of active tuberculosis among older individuals with latent tuberculosis infection: a cohort study in two high-epidemic sites in eastern China.

Background: The influencing factors of the process from latent tuberculosis infection (LTBI) to the onset of active tuberculosis (TB) remain unknown among different population groups, especially among older individuals in high-incidence areas. This study aimed to investigate the development of active TB among older adults with LTBI and identify groups in greatest need of improved prevention and control strategies for TB. Methods: In 2021, we implemented an investigation among older individuals (≥ 65 years old) in two towns in Zhejiang Province with the highest incidence of TB. All participants underwent assessment using standardized questionnaires, physical examinations, interferon-gamma release assays, and chest radiography. All the participants with suspected TB based on the clinical symptoms or abnormal chest radiography results, as well as those with LTBI, were referred for diagnostic investigation in accordance with the national guidelines. Those with an initial diagnosis of TB were then excluded, whereas those with LTBI were included in a follow-up at baseline. Incident patients with active TB were identified from the Chinese Tuberculosis Management Information System, and a multivariate Cox regression model was used to estimate the incidence and risk of TB among those with LTBI. Results: In total, 667 participants with LTBI were followed up for 1,315.3 person-years, revealing a disease density of 1,292.5 individuals/100,000 person-years (17/1,315.3). For those with LTBI, chest radiograph abnormalities had adjusted hazard ratios for active TB of 4.9 (1.6-15.3). Conclusions: The presence of abnormal chest radiography findings increased the risk of active TB among older individuals with LTBI in high-epidemic sites in eastern China.

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.

Partial recovery of tuberculosis preventive treatment in Brazil after pandemic drawback.

Brazil was heavily affected by COVID-19 both with death toll and economically, with absence of a centralized Federal Government response. Tuberculosis (TB) notifications decreased in 2020 but partial recovery was observed in 2021. We have previously shown a sharp (93%) reduction in TB preventive treatment notifications among five Brazilian cities with more than 1,000 notifications in 2021. We hypothesized TB preventive treatment would also recover. We updated the previous analysis by adding other cities that hold more than a 1,000 notifications until 2022. Data aggregated by 2-week periods were extracted from the Information System for Notifying People Undergoing Treatment for LTBI (IL-TB). Biweekly percentage change (BPC) of notifications until October 2022 and outcomes until July 2022 (in the two weeks of TB preventive treatment initiation) were analyzed using Joinpoint software. A total of 39,701 notifications in 11 cities were included, 66% from São Paulo and Rio de Janeiro, Brazil. We found a significant increase of TB preventive treatment notifications in the beginning of 2021 (BPC range 1.4-49.6), with sustained progression in seven out of the 11 cities. Overall, median completion rates were 65%. In most cities, a gradual and steady decrease of treatment completion rates was found, except for Rio de Janeiro and Manaus (Amazonas State, Brazil), where a BPC of 1.5 and 1.2, respectively, was followed by a sustained increase. Notifications and completion proportions of TB preventive treatment were heterogeneous, which partly reflects the heterogeneity in local response to the pandemic. We found that notifications were recovered, and that the sharp 2021 decrease was no longer observed, which suggests delays in notification. In conclusion, the sharp reductions in TB preventive treatment completion rates in most cities might have been caused by delays in reporting; however, the sustained and progressive decrease are a concern.

Latent tuberculosis infection and infection-associated risk factors for miner workers with silicosis in eastern China.

OBJECTIVES: Silicosis people are at high risk of developing pulmonary tuberculosis. Whether silica exposure increases the likelihood of latent tuberculosis infection (LTBI) was not well understood, and potential factors involved in LTBI risk among silicosis people were not evaluated before. Thus, LTBI among silicosis people and potential risk factors for LTBI among silicosis people were evaluated in this study. METHODS: A cross-sectional study was undertaken for 130 miner workers with silicosis. The QFT-GIT was performed for LTBI detection. RESULTS: The LTBI was high to 31.6% (36/114) for silicosis participants, and 13.1% (13/99) had a history of tuberculosis. Drinking was associated with LTBI risk (OR = 6.92, 95%CI, 1.47-32.66, P = 0.015). Meanwhile, tunneling work was associated with an increased risk of LTBI compared with other mining occupations (OR = 3.91,95%CI,1.20-12.70, P = 0.024). CONCLUSIONS: The LTBI rate of silicosis participants was high and more than 10% had a history of tuberculosis. Drinking alcohol and tunneling were independent risk factors for LTBI in silicosis participants.

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.

Latent tuberculosis prevalence, diagnosis and treatment in Multiple Sclerosis as a strategy for reducing infection reactivation during immunosuppressant therapy.

BACKGROUND: Tuberculosis is an infectious disease with a risk of reactivation in Multiple Sclerosis patients on immunosuppressant therapy. Diagnosis and treatment of Latent Tuberculosis Infection (LTBI) prevents the infection. OBJECTIVE: To diagnose and treat LTBI in Multiple Sclerosis (MS). METHODS: Cross-sectional study of the prevalence and treatment of LTBI in MS, between February 2021 and June 2023. LTBI was defined as an absence of symptoms, positive PPD or IGRA and normal chest X-ray. RESULTS: Of the 58 patients with MS, 17 (29.3 %) were diagnosed with LTBI, 15 with PPD > 5 mm and 2 with positive IGRA, 10 (58.8 %) female and 7 (41.1 %) male, mean age of 41.3 (SD ±13.4) years. All patients with LTBI were treated with immunomodulators or immunosuppressants: Fingolimod 5 (29.4 %), Natalizumab 5 (29.4 %), Cladribine 2 (11.8 %), Glatiramer 2 (11.8 %), Ocrelizumab 2 (11.8 %), and Interferon beta 1 (5.9 %). Steroids therapy for relapses, were used in 5/17 (93.8 %) with LTBI and 30/37 (81.1 %) without LTBI. To treat LTBI, 11 (64.7 %) received Isoniazid and 6 (35.3 %) Isoniazid plus Rifapentine. Hepatotoxicity occurred in 3 (17.6 %) with INH. There were no interruptions of ILTB treatment during the study. CONCLUSION: The prevalence of LTBI was found to be high and treatment proved safe.

A Mathematical Model for the Impact of 3HP and Social Programme Implementation on the Incidence and Mortality of Tuberculosis: Study in Brazil.

In this paper, we presented a mathematical model for tuberculosis with treatment for latent tuberculosis cases and incorporated social implementations based on the impact they will have on tuberculosis incidence, cure, and recovery. We incorporated two variables containing the accumulated deaths and active cases into the model in order to study the incidence and mortality rate per year with the data reported by the model. Our objective is to study the impact of social program implementations and therapies on latent tuberculosis in particular the use of once-weekly isoniazid-rifapentine for 12 weeks (3HP). The computational experimentation was performed with data from Brazil and for model calibration, we used the Markov Chain Monte Carlo method (MCMC) with a Bayesian approach. We studied the effect of increasing the coverage of social programs, the Bolsa Familia Programme (BFP) and the Family Health Strategy (FHS) and the implementation of the 3HP as a substitution therapy for two rates of diagnosis and treatment of latent at 1% and 5%. Based of the data obtained by the model in the period 2023-2035, the FHS reported better results than BFP in the case of social implementations and 3HP with a higher rate of diagnosis and treatment of latent in the reduction of incidence and mortality rate and in cases and deaths avoided. With the objective of linking the social and biomedical implementations, we constructed two different scenarios with the rate of diagnosis and treatment. We verified with results reported by the model that with the social implementations studied and the 3HP with the highest rate of diagnosis and treatment of latent, the best results were obtained in comparison with the other independent and joint implementations. A reduction of the incidence by 36.54% with respect to the model with the current strategies and coverage was achieved, and a greater number of cases and deaths from tuberculosis was avoided.

Screening for latent tuberculosis in migrants-status quo and future challenges.

OBJECTIVES: To review the evidence that migrants from tuberculosis (TB) high-incidence countries migrating to TB low-incidence countries significantly contribute to active TB cases in the counties of destination, primarily through reactivation of latent TB. METHODS: This is a narrative review. The different screening programs in the countries of destination are reviewed either based on screening and preventive treatment of latent TB pre or more commonly - post arrival. RESULTS: Screening can be performed using interferon-gamma release assays (IGRA) or tuberculin skin tests (TST). Preventive treatment of latent TB is using either monotherapy with isoniazid, or in combination with rifampicin or rifapentine. We discuss the ethical issues of preventive treatment in asymptomatic individuals and how these are addressed in different screening programs. CONCLUSION: Screening migrants from TB high endemic countries to TB low endemic countries is beneficial. There is a lack of standardization and agreement on screening protocols, follow up and treatment.

Tuberculin skin test and Interferon-gamma release assay agreement, and associated factors with latent tuberculosis infection, in medical and nursing students in Bandung, Indonesia.

BACKGROUND: No gold standard diagnostic test exists for latent tuberculosis infection (LTBI). The intra-dermal tuberculin skin test (TST) has known limitations and Interferon-gamma release assays (IGRA) have been developed as an alternative. We aimed to assess agreement between IGRA and TST, and risk factors for test positivity, in Indonesian healthcare students. METHODS: Medical and nursing students starting their clinical training were screened using IGRA and TST. Agreement between the two tests was measured using Cohen's Kappa coefficient. Logistic regression was used to identify factors associated with test positivity. RESULTS: Of 266 students, 43 (16.2%) were IGRA positive and 85 (31.9%) TST positive. Agreement between the two tests was 74.7% (kappa 0.33, 95% CI 0.21-0.45, P<0.0001). Students who had direct contact with family or friends with TB were less likely to be test positive using IGRA (AOR 0.18, 95% CI 0.05-0.64) and using TST (AOR 0.51, 95% CI 0.26-0.99). CONCLUSION: Test positivity for LTBI was lower when measured by IGRA than by TST, with poor agreement between the two tests. Known close TB contact was unexpectedly negatively associated with positivity by either test. Longitudinal studies may be required to help determine the best test for LTBI in healthcare students in Indonesia.

Mycobacterium tuberculosis latent infection in healthcare students: systematic review of prevalence.

OBJECTIVE: The aim of this study was to synthesize the evidence on the prevalence of latent Mycobacterium tuberculosis infection (LTBI) among undergraduate health care students. METHODS: A systematic review of prevalence with meta-analysis was conducted. Prospective and retrospective cohorts and cross-sectional studies involving probable exposure to M. tuberculosis during undergraduate education, along with the tuberculin skin test (TST) or interferon-γ release assay (IGRA) for investigation of latent tuberculosis were searched. Searches were conducted in MEDLINE, CINAHL, EMBASE, LILACS, Scopus, and Web of Science databases. Independent reviewers were responsible for the selection and inclusion of studies. Data were extracted, critically appraised, and synthesized using the JBI approach. PRISMA was used to report the study. RESULTS: Twenty-two studies were analyzed. The overall prevalence in healthcare undergraduate students was 12.53%. CONCLUSION: The prevalence of LTBI in undergraduate health students was high for such a highly educated population. Screening with TST and/or IGRA and chemoprophylaxis, when necessary, should be provided to undergraduate health students when in contact with respiratory symptomatic patients.

Characteristics, management, and outcome of tuberculosis after liver transplant: A case series and literature review.

BACKGROUND: Liver transplant recipients are at risk of tuberculosis, which is particularly difficult-to diagnose and to treat in this population. METHODS: Retrospective study of all cases of tuberculosis diagnosed from 2007 to 2022 in the French network of liver transplant sites. RESULTS: Twenty-three liver transplant recipients were diagnosed with tuberculosis (six females, median age 59 years [interquartile range, 54-62]), with a median time lapse of 10 months [5-40.5] after transplant, and 38 days [26-60] after symptoms onset. Primary modes of pathogenesis were latent tuberculosis reactivation (n = 15) and transplant-related transmission (n = 3). Even though most patients with pre-transplant data had risk factors for tuberculosis (11/20), IFN-gamma release assay was performed in only three. Most cases involved extra-pulmonary tuberculosis (20/23, 87 %). With median follow-up of 63 months [24-108], five patients died (22 %), including four tuberculosis-related deaths. CONCLUSIONS: Extrapulmonary tuberculosis is a severe disease in liver transplant recipients. Systematic pre-transplant screening of latent tuberculosis may prevent most of them.

Adverse events of biological agents in pediatric rheumatologic diseases.

OBJECTIVES: To evaluate adverse events (AEs) in pediatric patients with rheumatologic diseases being treated with approved or off-label biologic agents (BAs). METHODS: This observational, retrospective, multicenter study was conducted from 2010 to 2022 in patients under 18 years of age with rheumatic diseases who were receiving interleukin-1 antibodies (Anti-IL1), interleukin-6 antibodies (Anti-IL6), and tumor necrosis factor alpha inhibitors (anti-TNF). Efficacy, AEs, and timing of AEs were collected from electronic medical records. RESULTS: Three hundred and fifteen BAs were prescribed to 237 patients. Fifty AEs occurred in 44 patients (18.6%). Anti-TNF exposure was present in 8 (72.2%) of 11 patients with latent tuberculosis (TB) and in all 7 patients with herpes infections. Four of 6 patients (66.7%) with recurrent upper respiratory tract infections and 7 of 8 patients (87.5%) with local skin reactions were on Anti-IL1. The cutoff value for latent TB development was determined as 23.5 months by ROC analysis (AUC: 0.684 ± 0.072, p = 0.038, 95% CI: 0.54-0.82). In patients who used BA for 23.5 months or more, the risk of latent TB was 5.94-fold (p = 0.024, 95% CI: 1.26-27.97). Drug rash with eosinophilia and systemic symptoms (DRESS) occurred in 2 patients on anakinra, and anaphylaxis occurred in 1 patient on anti-IL6. There were no cases of malignancy or death in any patient. CONCLUSION: The physician should be vigilant for latent TB in patients exposed to BA for more than 2 years. While local skin reactions are more prevalent in patients receiving anti-IL1, severe skin reactions such as DRESS may also occur.

The association of dietary patterns with latent tuberculosis infection among young adults: A case-control study in Shanghai.

INTRODUCTION: In developing and underdeveloped countries, undernutrition plays a major role in subverting the immune system, leading to an increase in TB infections; this study investigated the associations between dietary patterns and latent tuberculosis infection risk among young adults in Shanghai. METHODOLOGY: In a case-control study, 96 cases of latent tuberculosis infection and 192 healthy controls were studied among contacts of students in clusters of tuberculosis epidemics in colleges from January 2021 to March 2023. A standardized questionnaire assessing sociodemographic, lifestyle, and dietary characteristics was applied. Food intake was estimated using a 95-item semiquantitative Food Frequency Questionnaire. Using the principal component analysis to extract dietary patterns from food groups intake. Logistic regression models were applied. RESULTS: Four dietary patterns were identified: "traditional balanced" pattern, "unsaturated fatty acid" pattern, "snack" pattern, and "protein and fruit" pattern. Four components explaining 64.52% of the total variation in consumption were derived. In a conditional logistic regression analysis, three models were created. After adjusting for various confounders, compared to "snack" pattern, the risk of latent TB infection was 91% lower in the "traditional balanced" pattern (OR 0.05, 95% CI 0.01, 0.38, p = 0.004). CONCLUSIONS: To prevent TB infection among young adults living in high TB burden areas, a balanced dietary pattern rather than a "snack" pattern should be promoted in school settings. Future research should explore the risk of developing active tuberculosis in Mtb-infected people with different dietary patterns and the prevention of this risk by healthy dietary patterns.

Relationship between biologic modifying agents and development of latent tuberculosis in pediatrics.

INTRODUCTION: Biologic modifying agents are associated with an increased risk for infection with mycobacteria. The aim of this study is to document patients who received different biologic modifying therapies in our pediatric rheumatology department and the possibility of development of tuberculosis (TB). METHODOLOGY: This retrospective study was conducted in Ankara City Hospital. Pediatric patients who were treated with biologic modifying agents between 2010-2020 were documented. Development of TB and the risk factors were assessed in this patient group. RESULTS: There were 72 patients who were treated with different biologic modifying agents. Tuberculin skin test (TST) was positive in 7 (9.7%) patients during follow up. Three patients whose TST was positive had received canakinumab, 2 received etanercept, 1 received adalimumab and 1 received anakinra. Median duration of therapy was 43.5 (16.5-168) months for these patients and the duration was longer than patients who did not develop latent tuberculosis (p = 0.04). Patients who developed latent TB under treatment were significantly older than the patients who did not (p = 0.01). CONCLUSIONS: According to our findings, 9.7% of pediatric patients who received biologic modifying agent therapy developed latent TB. Patients who developed latent TB were older, and the duration of treatment was longer than patients who did not develop latent TB. Although not statistically significant, canakinumab, which is known as an agent less likely to cause TST conversion, was in fact the most common agent that caused TST conversion.

Cost-effectiveness of latent tuberculosis infection testing and treatment with 6-week regimen among key population in rural communities in China: a decision analysis study.

PURPOSE: Several model studies suggested the implementation of latent tuberculosis infection (LTBI) testing and treatment could greatly reduce the incidence of tuberculosis (TB) and achieve the 2035 target of the "End TB" Strategy in China. The present study aimed to evaluate the cost-effectiveness of LTBI testing and TB preventive treatment among key population (≥ 50 years old) susceptible to TB at community level in China. METHODS: A Markov model was developed to investigate the cost-effectiveness of LTBI testing using interferon gamma release assay (IGRA) and subsequent treatment with 6-month daily isoniazid regimen (6H) (as a standard regimen for comparison) or 6-week twice-weekly rifapentine and isoniazid regimen (6-week H2P2) in a cohort of 10,000 adults with an average initial age of 50 years. RESULTS: In the base-case analysis, LTBI testing and treatment with 6H was dominated (i.e., more expensive with a lower quality-adjusted life year (QALY)) by LTBI testing and treatment with 6-week H2P2. LTBI testing and treatment with 6-week H2P2 was more effective than no intervention at a cost of $20,943.81 per QALY gained, which was below the willingness-to-pay (WTP) threshold of $24,211.84 per QALY gained in China. The one-way sensitivity analysis showed the change of LTBI prevalence was the parameter that most influenced the results of the incremental cost-effectiveness ratios (ICERs). CONCLUSION: As estimated by a Markov model, LTBI testing and treatment with 6-week H2P2 was cost-saving compared with LTBI testing and treatment with 6H, and it was considered to be a cost-effective option for TB control in rural China.

Safety and outcome of treatment of latent tuberculosis infection in liver transplant recipients.

PURPOSE: Liver transplant (LT) recipients have an increased risk of tuberculosis (TB), which is associated with higher mortality rates. This retrospective cohort study assessed the outcome and tolerability of screening and treatment of latent tuberculosis infection (LTBI) in LT recipients. METHODS: Between March 2020 and February 2022, all adult LT candidates at our institution were screened for LTBI. The candidates who tested positive for interferon-γ-releasing assay or met epidemiological or clinical-radiological criteria for LTBI were treated and monitored. RESULTS: Among the 857 LT recipients, 199 (23.2%) were diagnosed with LTBI, of which 171 (85.9%) initiated LTBI treatment. The median duration of follow-up was 677 days. Adequate LTBI treatment occurred in 141/171 (82.5%) patients and was discontinued prematurely in 30/171 (17.5%) patients. The most common reason for discontinuation was liver enzyme elevation (11/30, 36.7%), although only five discontinued treatment due to suspicion of isoniazid-associated hepatotoxicity. None of the LTBI-treated patients developed active TB during the follow-up period, while 3.6% (1/28) of untreated LTBI patients and 0.6% (4/658) of patients without LTBI developed TB. CONCLUSION: These findings demonstrate that LTBI screening and treatment is a safe and effective strategy to prevent TB in LT recipients. However, monitoring for adverse events and liver enzyme elevation is recommended.

Interferon-gamma release assay conversion after Mycobacterium tuberculosis exposure specifically associates with greater risk of progression to tuberculosis: A prospective cohort study in Leicester, UK.

OBJECTIVES: We investigated whether quantifying the serial QuantiFERON-TB Gold (QFT) response improves tuberculosis (TB) risk stratification in pulmonary TB (PTB) contacts. METHODS: A total of 297 untreated adult household PTB contacts, QFT tested at baseline and 3 months after index notification, were prospectively observed (median 1460 days). Normal variance of serial QFT responses was established in 46 extrapulmonary TB contacts. This informed categorisation of the response in QFT-positive PTB contacts as converters, persistently QFT-positive with significant increase (PPincrease), and without significant increase (PPno-increase). RESULTS: In total, eight co-prevalent TB (disease ≤3 months after index notification) and 12 incident TB (>3 months after index notification) cases were diagnosed. Genetic linkage to the index strain was confirmed in all culture-positive progressors. The cumulative 2-year incident TB risk in QFT-positive contacts was 8.4% (95% confidence interval, 3.0-13.6%); stratifying by serial QFT response, significantly higher risk was observed in QFT converters (28%), compared with PPno-increase (4.8%) and PPincrease (3.7%). Converters were characterised by exposure to index cases with a shorter interval from symptom onset to diagnosis (median reduction 50.0 days, P = 0.013). CONCLUSIONS: QFT conversion, rather than quantitative changes of a persistently positive serial QFT response, is associated with greater TB risk and exposure to rapidly progressive TB.