Aerosolization of viable Mycobacterium tuberculosis bacilli by tuberculosis clinic attendees independent of sputum-Xpert Ultra status.

Potential Mycobacterium tuberculosis (Mtb) transmission during different pulmonary tuberculosis (TB) disease states is poorly understood. We quantified viable aerosolized Mtb from TB clinic attendees following diagnosis and through six months' follow-up thereafter. Presumptive TB patients (n=102) were classified by laboratory, radiological, and clinical features into Group A: Sputum-Xpert Ultra-positive TB (n=52), Group B: Sputum-Xpert Ultra-negative TB (n=20), or Group C: TB undiagnosed (n=30). All groups were assessed for Mtb bioaerosol release at baseline, and subsequently at 2 wk, 2 mo, and 6 mo. Groups A and B were notified to the national TB program and received standard anti-TB chemotherapy; Mtb was isolated from 92% and 90% at presentation, 87% and 74% at 2 wk, 54% and 44% at 2 mo and 32% and 20% at 6 mo, respectively. Surprisingly, similar numbers were detected in Group C not initiating TB treatment: 93%, 70%, 48% and 22% at the same timepoints. A temporal association was observed between Mtb bioaerosol release and TB symptoms in all three groups. Persistence of Mtb bioaerosol positivity was observed in ~30% of participants irrespective of TB chemotherapy. Captured Mtb bacilli were predominantly acid-fast stain-negative and poorly culturable; however, three bioaerosol samples yielded sufficient biomass following culture for whole-genome sequencing, revealing two different Mtb lineages. Detection of viable aerosolized Mtb in clinic attendees, independent of TB diagnosis, suggests that unidentified Mtb transmitters might contribute a significant attributable proportion of community exposure. Additional longitudinal studies with sputum culture-positive and -negative control participants are required to investigate this possibility.

The plasma kynurenine-to-tryptophan ratio as a biomarker of tuberculosis disease in people living with HIV on antiretroviral therapy: an exploratory nested case-control study.

BACKGROUND: Non-sputum-based tests are needed to predict or diagnose tuberculosis (TB) disease in people living with HIV (PWH). The enzyme indoleamine 2, 3-dioxygenase-1 (IDO1) is expressed in tuberculoid granuloma and catabolizes tryptophan (Trp) to kynurenine (Kyn). IDO1 activity compromises innate and adaptive immune responses, promoting mycobacterial survival. The plasma Kyn-to-Trp (K/T) ratio is a potential TB diagnostic and/or predictive biomarker in PWH on long-term antiretroviral therapy (ART). METHODS: We compared plasma K/T ratios in samples from PWH, who were followed up prospectively and developed TB disease after ART initiation. Controls were matched for age and duration of ART. Kyn and Trp were measured at 3 timepoints; at TB diagnosis, 6 months before TB diagnosis and 6 months after TB diagnosis, using ultra performance liquid chromatography combined with mass spectrometry. RESULTS: The K/T ratios were higher for patients with TB disease at time of diagnosis (median, 0.086; IQR, 0.069-0.123) compared to controls (0.055; IQR 0.045-0.064; p = 0.006), but not before or after TB diagnosis. K/T ratios significantly declined after successful TB treatment, but increased upon treatment failure. The K/T ratios showed a parabolic correlation with CD4 cell counts in participants with TB (p = 0.005), but there was no correlation in controls. CONCLUSIONS: The plasma K/T ratio helped identify TB disease and may serve as an adjunctive biomarker for for monitoring TB treatment in PWH. Validation studies to ascertain these findings and evaluate the optimum cut-off for diagnosis of TB disease in PWH should be undertaken in well-designed prospective cohorts. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00411983.

An Aspiration to Radically Shorten Phase 3 Tuberculosis Vaccine Trials.

A new tuberculosis vaccine is a high priority. However, the classical development pathway is a major deterrent. Most tuberculosis cases arise within 2 years after Mycobacterium tuberculosis exposure, suggesting a 3-year trial period should be possible if sample size is large to maximize the number of early exposures. Increased sample size could be facilitated by working alongside optimized routine services for case ascertainment, with strategies for enhanced case detection and safety monitoring. Shortening enrolment could be achieved by simplifying screening criteria and procedures and strengthening site capacity. Together, these measures could enable radically shortened phase 3 tuberculosis vaccine trials.

Disease Transmission by Patients With Subclinical Tuberculosis.

BACKGROUND: Subclinical tuberculosis has been increasingly recognized as a separate state in the spectrum of the disease. However, evidence on the transmissibility of subclinical tuberculosis is still inconclusive. METHODS: We re-analyzed the data from the 2007 combined tuberculosis prevalence and tuberculin surveys in Vietnam. Poisson regression with robust standard errors was conducted to assess the effect of clinical presentation of individuals with tuberculosis in the household on tuberculin skin test (TST) positivity among children aged 6-14 years who participated in the tuberculin survey, adjusting for child's age, smear status of the index patient, and other covariates. RESULTS: In the multivariate analysis, we found significantly increased risks for TST positivity in children living with patients with clinical, smear-positive tuberculosis, compared with those living with individuals without tuberculosis (adjusted risk ratio [aRR]: 3.04; 95% confidence interval [CI]: 2.00-4.63) and with those living with patients with subclinical tuberculosis, adjusting for index smear status (aRR: 2.26; 95% CI: 1.03-4.96). Among children aged 6-10 years, those living with patients with clinical, smear-positive tuberculosis and those living with patients with subclinical, smear-positive tuberculosis had similarly increased risks of TST positivity compared with those living with individuals without tuberculosis (aRRs [95% CI] of 3.56 [1.91-6.62] and 3.11 [1.44-6.72], respectively). CONCLUSIONS: Our findings support the hypothesis that smear-positive subclinical tuberculosis contributes to Mycobacterium tuberculosis transmission. To eliminate tuberculosis in 2035, control strategies need to address subclinical presentations of the disease.

Influence of Sex and Sex-Based Disparities on Prevalent Tuberculosis, Vietnam, 2017-2018.

To assess sex disparities in tuberculosis in Vietnam, we conducted a nested, case-control study based on a 2017 tuberculosis prevalence survey. We defined the case group as all survey participants with laboratory-confirmed tuberculosis and the control group as a randomly selected group of participants with no tuberculosis. We used structural equation modeling to describe pathways from sex to tuberculosis according to an a priori conceptual framework. Our analysis included 1,319 participants, of whom 250 were case-patients. We found that sex was directly associated with tuberculosis prevalence (adjusted odds ratio for men compared with women 3.0 [95% CI 1.7-5.0]) and indirectly associated through other domains. The strong sex difference in tuberculosis prevalence is explained by a complex interplay of factors relating to behavioral and environmental risks, access to healthcare, and clinical manifestations. However, after controlling for all those factors, a direct sex effect remains that might be caused by biological factors.

Drivers determining tuberculosis disease screening yield in four European screening programmes: a comparative analysis.

BACKGROUND: The World Health Organization End TB Strategy emphasises screening for early diagnosis of tuberculosis (TB) in high-risk groups, including migrants. We analysed key drivers of TB yield differences in four large migrant TB screening programmes to inform TB control planning and feasibility of a European approach. METHODS: We pooled individual TB screening episode data from Italy, the Netherlands, Sweden and the UK, and analysed predictors and interactions for TB case yield using multivariable logistic regression models. RESULTS: Between 2005 and 2018 in 2 302 260 screening episodes among 2 107 016 migrants to four countries, the programmes identified 1658 TB cases (yield 72.0 (95% CI 68.6-75.6) per 100 000). In logistic regression analysis, we found associations between TB screening yield and age (≥55 years: OR 2.91 (95% CI 2.24-3.78)), being an asylum seeker (OR 3.19 (95% CI 1.03-9.83)) or on a settlement visa (OR 1.78 (95% CI 1.57-2.01)), close TB contact (OR 12.25 (95% CI 11.73-12.79)) and higher TB incidence in the country of origin. We demonstrated interactions between migrant typology and age, as well as country of origin. For asylum seekers, the elevated TB risk remained similar above country of origin incidence thresholds of 100 per 100 000. CONCLUSIONS: Key determinants of TB yield included close contact, increasing age, incidence in country of origin and specific migrant groups, including asylum seekers and refugees. For most migrants such as UK students and workers, TB yield significantly increased with levels of incidence in the country of origin. The high, country of origin-independent TB risk in asylum seekers above a 100 per 100 000 threshold could reflect higher transmission and re-activation risk of migration routes, with implications for selecting populations for TB screening.

Target product profiles: tests for tuberculosis treatment monitoring and optimization.

The World Health Organization has developed target product profiles containing minimum and optimum targets for key characteristics for tests for tuberculosis treatment monitoring and optimization. Tuberculosis treatment optimization refers to initiating or switching to an effective tuberculosis treatment regimen that results in a high likelihood of a good treatment outcome. The target product profiles also cover tests of cure conducted at the end of treatment. The development of the target product profiles was informed by a stakeholder survey, a cost-effectiveness analysis and a patient-care pathway analysis. Additional feedback from stakeholders was obtained by means of a Delphi-like process, a technical consultation and a call for public comment on a draft document. A scientific development group agreed on the final targets in a consensus meeting. For characteristics rated of highest importance, the document lists: (i) high diagnostic accuracy (sensitivity and specificity); (ii) time to result of optimally ≤ 2 hours and no more than 1 day; (iii) required sample type to be minimally invasive, easily obtainable, such as urine, breath, or capillary blood, or a respiratory sample that goes beyond sputum; (iv) ideally the test could be placed at a peripheral-level health facility without a laboratory; and (v) the test should be affordable to low- and middle-income countries, and allow wide and equitable access and scale-up. Use of these target product profiles should facilitate the development of new tuberculosis treatment monitoring and optimization tests that are accurate and accessible for all people being treated for tuberculosis.

L'Organisation mondiale de la santé a élaboré des profils de produits cibles contenant des cibles minimales et optimales pour les caractéristiques principales des essais destinés au suivi et à l'optimisation du traitement de la tuberculose. L'optimisation du traitement de la tuberculose fait référence à l'instauration d'un régime de traitement efficace de la tuberculose ou à l'adoption d'un tel régime, avec une probabilité élevée d'obtenir de bons résultats thérapeutiques. Les profils de produits cibles couvrent également les essais de guérison effectués à l'issue du traitement. Les profils de produits cibles ont été élaborés sur la base d'un sondage auprès des parties prenantes, d'une analyse coût-efficacité et d'une analyse du parcours de soins du patient. Des retours supplémentaires des parties prenantes ont été obtenus au moyen d'un processus créé selon la méthode Delphi, d'une consultation technique et d'un appel à commentaires publics sur un projet de document. Un groupe d'élaboration scientifique s'est mis d'accord sur les objectifs finaux lors d'une réunion de concertation. En ce qui concerne les caractéristiques jugées les plus importantes, le document énumère ce qui suit: (i) une grande précision diagnostique (sensibilité et spécificité); (ii) un délai idéal d'obtention des résultats ≤ 2 heures et au maximum de 1 jour; (iii) le type d'échantillon requis doit être peu invasif et facile à obtenir, comme l'urine, l'haleine ou le sang capillaire, ou bien un échantillon respiratoire au-delà des expectorations; (iv) idéalement, l'essai pourrait avoir lieu dans un établissement de santé périphérique sans laboratoire ; et (v) l'essai devrait être abordable pour les pays à revenu faible et intermédiaire et permettre un accès large et équitable ainsi qu'une mise à l'échelle. L'utilisation de ces profils de produits cibles devrait faciliter la mise au point de nouveaux essais de surveillance et d'optimisation du traitement de la tuberculose qui soient précis et accessibles à toutes les personnes suivant un traitement pour la tuberculose.

La Organización Mundial de la Salud ha elaborado perfiles de productos objetivo que contienen objetivos mínimos y óptimos para las características principales de las pruebas de seguimiento y optimización del tratamiento de la tuberculosis. La optimización del tratamiento de la tuberculosis consiste en iniciar o cambiar a un régimen eficaz de tratamiento de la tuberculosis que ofrezca una alta probabilidad de un buen resultado terapéutico. Los perfiles de productos objetivo también abarcan las pruebas de curación realizadas al final del tratamiento. La elaboración de los perfiles de los productos objetivo se basó en una encuesta a las partes interesadas, un análisis de rentabilidad y un análisis de la vía de atención al paciente. Se obtuvo información adicional de las partes interesadas mediante un proceso tipo Delphi, una consulta técnica y una convocatoria de comentarios públicos sobre un borrador del documento. Un grupo de desarrollo científico acordó los objetivos finales en una reunión de consenso. Para las características clasificadas de mayor importancia, el documento enumera: (i) alta precisión diagnóstica (sensibilidad y especificidad); (ii) tiempo hasta el resultado de óptimamente ≤ 2 horas y no más de 1 día; (iii) el tipo de muestra requerida debe ser mínimamente invasiva, fácil de obtener, como orina, aliento o sangre capilar, o una muestra respiratoria que vaya más allá del esputo; (iv) idealmente la prueba podría realizarse en un centro sanitario periférico sin laboratorio; y (v) la prueba debe ser asequible para los países de ingresos bajos y medios y permitir un acceso amplio y equitativo y su expansión. El uso de estos perfiles de producto objetivo debería facilitar el desarrollo de pruebas nuevas de seguimiento y optimización del tratamiento de la tuberculosis que sean precisas y accesibles para todas las personas que reciben tratamiento antituberculoso.

How "Subclinical" is Subclinical Tuberculosis? An Analysis of National Prevalence Survey Data from Zambia.

BACKGROUND: Pulmonary tuberculosis infection can manifest in different states, including subclinical tuberculosis. It is commonly defined as confirmed tuberculosis without the classic symptoms (commonly, persistent cough for ≥2 weeks). This narrow definition likely poses limitations for surveillance and control measures. The aims of the current study were to characterize the clinical presentation of tuberculosis; estimate the prevalence of subclinical tuberculosis among individuals with bacteriologically confirmed tuberculosis, using various definitions; and investigate risk factors for subclinical as opposed to clinical tuberculosis in a population-based survey. METHODS: We conducted a secondary analysis of data from a nationally representative tuberculosis prevalence survey from Zambia in 2013-2014, in which participants were screened for tuberculosis based on chest radiographic findings and symptoms. Tuberculosis was defined as culture-positive or GeneXpert MTB/RIF test-positive sputum. Risk factors for subclinical tuberculosis were assessed by means of multivariable logistic regression. RESULTS: Of 257 participants with confirmed tuberculosis, 104 (40.5%) were without cough persisting ≥2 weeks. Only 23 (22.1%) of these did not present with any other common symptoms. Those without cough persisting ≥2 weeks frequently reported other symptoms, particularly chest pain (46.2%) and weight loss (38.5%); 36 (34.6%) reported experiencing other symptoms persisting ≥4 weeks. Female subjects were more likely to report no cough persisting ≥2 weeks, as were relatively wealthier individuals. CONCLUSIONS: The commonly used definition of subclinical tuberculosis includes a large proportion of individuals who have other tuberculosis-suggestive symptoms. Requiring cough ≥2 weeks for tuberculosis diagnosis likely misses many active tuberculosis infections and allows a large reservoir of likely transmissible tuberculosis to remain undetected.

Social determinants of the changing tuberculosis prevalence in Viet Nam: Analysis of population-level cross-sectional studies.

BACKGROUND: An ecological relationship between economic development and reduction in tuberculosis prevalence has been observed. Between 2007 and 2017, Viet Nam experienced rapid economic development with equitable distribution of resources and a 37% reduction in tuberculosis prevalence. Analysing consecutive prevalence surveys, we examined how the reduction in tuberculosis (and subclinical tuberculosis) prevalence was concentrated between socioeconomic groups. METHODS AND FINDINGS: We combined data from 2 nationally representative Viet Nam tuberculosis prevalence surveys with provincial-level measures of poverty. Data from 94,156 (2007) and 61,763 (2017) individuals were included. Of people with microbiologically confirmed tuberculosis, 21.6% (47/218) in 2007 and 29.0% (36/124) in 2017 had subclinical disease. We constructed an asset index using principal component analysis of consumption data. An illness concentration index was estimated to measure socioeconomic position inequality in tuberculosis prevalence. The illness concentration index changed from -0.10 (95% CI -0.08, -0.16; p = 0.003) in 2007 to 0.07 (95% CI 0.06, 0.18; p = 0.158) in 2017, indicating that tuberculosis was concentrated among the poorest households in 2007, with a shift towards more equal distribution between rich and poor households in 2017. This finding was similar for subclinical tuberculosis. We fitted multilevel models to investigate relationships between change in tuberculosis prevalence, individual risks, household socioeconomic position, and neighbourhood poverty. Controlling for provincial poverty level reduced the difference in prevalence, suggesting that changes in neighbourhood poverty contribute to the explanation of change in tuberculosis prevalence. A limitation of our study is that while tuberculosis prevalence surveys are valuable for understanding socioeconomic differences in tuberculosis prevalence in countries, given that tuberculosis is a relatively rare disease in the population studied, there is limited power to explore socioeconomic drivers. However, combining repeated cross-sectional surveys with provincial deprivation estimates during a period of remarkable economic growth provides valuable insights into the dynamics of the relationship between tuberculosis and economic development in Viet Nam. CONCLUSIONS: We found that with equitable economic growth and a reduction in tuberculosis burden, tuberculosis became less concentrated among the poor in Viet Nam.

Framing the detection of incipient tuberculosis infection: A qualitative study of political prioritisation.

OBJECTIVE: Incipient Tuberculosis (ITB) refers to Mycobacterium tuberculosis infection that is likely to progress to active disease in the absence of treatment, but without clinical signs, symptoms, radiographic or microbiological evidence of disease. Biomarker-based tests to diagnose incipient TB hold promise for better prediction and, through TB preventive therapy, prevention of disease. This study explored current and future framing and prioritisation of ITB. METHODS: Twenty-two interviews across eight countries were conducted. A modified Shiffman & Smith Framework, containing four categories-Ideas, Issue Characteristics, Actor Power, and Political Contexts-was used to analyse the current landscape and potential for prioritisation of diagnosis and treatment of ITB. RESULTS: Latent TB policy implementation has been slow due to technical, logistical and financial challenges, and because it has been framed in a manner non-conducive to gaining political priority. Framing ITB testing as 'early detection' rather than 'prediction', and its management as 'treatment' rather than 'preventive therapy', may help raise its importance in policies, and its acceptance among actors. CONCLUSION: Consensus surrounding the framing of ITB will be crucial for the successful adoption of ITB diagnostics and treatment. When designing ITB tools and policies, it will be important to address challenges that pertain to latent TB policies.

Incidence and factors associated with active tuberculosis among people living with HIV after long-term antiretroviral therapy in Thailand: a competing risk model.

BACKGROUND: Antiretroviral therapy (ART) is known to reduce tuberculosis (TB) incidence among people living with HIV (PLWH). However, studies describing the impact of long-term ART and CD4 count recovery on TB incidence remain scarce due to limited follow up in previous studies. We evaluated TB incidence in a long-term cohort of PLWH on ART in Thailand. METHODS: We conducted an analysis of PLWH aged ≥ 18 years who started ART between 1996 and December 2020. Participants were followed up every 6 months for routine HIV care. TB risk factors, body mass index (BMI), physical examination and full differential blood counts were evaluated at each clinic visit, and CD4 cell counts and HIV RNA every 12 months. Participants diagnosed with TB > 3 months after starting ART were classified as incident cases. Time to event models with death as a competing risk, were used to derive the TB cumulative incidence function (CIF) after ART initiation, and assess time-updated factors associated with incident TB using a six month lag. RESULTS: A total of 2,636 PLWH contributing 24,229 person years (PY) of follow-up on ART were analysed. Median age was 32.0 (IQR 27.4-37.6) years; 67.5% were male. Median CD4 cell count at ART initiation was 264 (IQR 167-379) cells/mm3 and median follow-up duration was 7.6 (IQR 1.9-15.7) years. During follow-up, 113 PLWH developed TB. The probability of incident TB was 0.7%, 1.7%, 3.3% and 4.3%, at 1, 2, 5 and 7 years after ART initiation, respectively. TB CIF was highest among participants with CD4 < 50 cells/mm3. The overall crude incidence of TB was 4.66 (95% CI 3.87-5.60) per 1000 PY. Low CD4 count, BMI < 18 kg/m2, and substance use in the previous six months were significantly associated with incident TB. Incidence declined with time on suppressive ART, but remained higher than the Thai general population 7 years after ART initiation (2.2 vs 1.5/1000 PY, respectively). CONCLUSION: Despite a marked reduction in TB incidence following ART, ongoing TB risk remains high among PLWH, despite long-term suppressive ART. Those with low CD4 cell counts, who are underweight, or currently having substance abuse should be carefully monitored.

Discordant results of Xpert MTB/Rif assay and BACTEC MGIT 960 liquid culture to detect Mycobacterium tuberculosis in community screening in Vietnam.

BACKGROUND: Xpert MTB/Rif, a molecular test to detect tuberculosis (TB), has been proven to have high sensitivity and specificity when compared with liquid culture in clinical settings. However, little is known about its performance in community TB screening. METHODS: In Vietnam, a national TB prevalence survey was conducted in 2017. Survey participants who screened positive by chest X-ray, cough symptoms and/or recent history of tuberculosis were requested to provide at least two sputum samples that were tested for Mycobacterium tuberculosis by Xpert MTB/Rif G4 (Xpert) and BACTEC MGIT960 culture (MGIT). RESULTS: There were 4,649 eligible participants provided both samples for testing. Among them, 236 (5.1%) participants tested positive for TB by Xpert, 244 (5.3%) tested positive by MGIT and 317 tested positive by at least one test; 163 (51.4%) had discordant test results. Of the positive Xpert, 162 (68.6%) showed a low or very low bacterial load. In multivariate logistic regression comparing discordant with Xpert-MGIT concordant positive results, discordant Xpert-positive results occurred more often among participants who had low sputum bacterial load, male sex, a history of TB treatment, or night sweats. The associated factors were male sex, abnormal chest X-ray and having night sweats when the logistic model was against those with both Xpert and MGIT negative. CONCLUSIONS: We found high rates of discordance in the performance of Xpert and MGIT for community-based TB case finding. In situations where the majority of TB cases are expected to have a low bacterial load, multiple diagnostic tests and/or multiple samples are required to reach sufficient sensitivity.

Annual Tuberculosis Preventive Therapy for Persons With HIV Infection : A Randomized Trial.

BACKGROUND: Tuberculosis preventive therapy for persons with HIV infection is effective, but its durability is uncertain. OBJECTIVE: To compare treatment completion rates of weekly isoniazid-rifapentine for 3 months versus daily isoniazid for 6 months as well as the effectiveness of the 3-month rifapentine-isoniazid regimen given annually for 2 years versus once. DESIGN: Randomized trial. (ClinicalTrials.gov: NCT02980016). SETTING: South Africa, Ethiopia, and Mozambique. PARTICIPANTS: Persons with HIV infection who were receiving antiretroviral therapy, were aged 2 years or older, and did not have active tuberculosis. INTERVENTION: Participants were randomly assigned to receive weekly rifapentine-isoniazid for 3 months, given either annually for 2 years or once, or daily isoniazid for 6 months. Participants were screened for tuberculosis symptoms at months 0 to 3 and 12 of each study year and at months 12 and 24 using chest radiography and sputum culture. MEASUREMENTS: Treatment completion was assessed using pill counts. Tuberculosis incidence was measured over 24 months. RESULTS: Between November 2016 and November 2017, 4027 participants were enrolled; 4014 were included in the analyses (median age, 41 years; 69.5% women; all using antiretroviral therapy). Treatment completion in the first year for the combined rifapentine-isoniazid groups (n = 3610) was 90.4% versus 50.5% for the isoniazid group (n = 404) (risk ratio, 1.78 [95% CI, 1.61 to 1.95]). Tuberculosis incidence among participants receiving the rifapentine-isoniazid regimen twice (n = 1808) or once (n = 1802) was similar (hazard ratio, 0.96 [CI, 0.61 to 1.50]). LIMITATION: If rifapentine-isoniazid is effective in curing subclinical tuberculosis, then the intensive tuberculosis screening at month 12 may have reduced its effectiveness. CONCLUSION: Treatment completion was higher with rifapentine-isoniazid for 3 months compared with isoniazid for 6 months. In settings with high tuberculosis transmission, a second round of preventive therapy did not provide additional benefit to persons receiving antiretroviral therapy. PRIMARY FUNDING SOURCE: The U.S. Agency for International Development through the CHALLENGE TB grant to the KNCV Tuberculosis Foundation.

High Rates of Recurrent Tuberculosis Disease: A Population-level Cohort Study.

BACKGROUND: Retreatment tuberculosis (TB) disease is common in high-prevalence settings. The risk of repeated episodes of recurrent TB is unknown. We calculated the rate of recurrent TB per subsequent episode by matching individual treatment episodes over a period of 13 years. METHODS: All recorded TB episodes in Cape Town between 2003 and 2016 were matched by probabilistic linkage of personal identifiers. Among individuals with a first episode notified in Cape Town and who completed their prior treatment successfully we estimated the recurrence rate stratified by subsequent episode and HIV status. We adjusted person-time to background mortality by age, sex, and HIV status. RESULTS: A total of 292 915 TB episodes among 263 848 individuals were included. The rate of recurrent TB was 16.4 per 1000 person-years (95% CI, 16.2-16.6), and increased per subsequent episode (8.4-fold increase, from 14.6 to 122.7 per 1000 from episode 2 to 6, respectively). These increases were similar stratified by HIV status. Rates among HIV positives were higher than among HIV negatives for episodes 2 and 3 (2- and 1.5-fold higher, respectively), and the same thereafter. CONCLUSIONS: TB recurrence rates were high and increased per subsequent episode, independent of HIV status. This suggests that HIV infection is insufficient to explain the high burden of recurrence; it is more likely due to a high annual risk of infection combined with an increased risk of infection or progression to disease associated with a previous TB episode. The very high recurrence rates would justify increased TB surveillance of patients with >1 episode.

Decline of Tuberculosis Burden in Vietnam Measured by Consecutive National Surveys, 2007-2017.

Vietnam, a high tuberculosis (TB) burden country, conducted national TB prevalence surveys in 2007 and 2017. In both surveys participants were screened by using a questionnaire and chest radiograph; sputum samples were then collected to test for Mycobacterium tuberculosis by smear microscopy and Löwenstein-Jensen culture. Culture-positive, smear-positive, and smear-negative TB cases were defined by laboratory results, and the prevalence of tuberculosis was compared between the 2 surveys. The results showed prevalence of culture-positive TB decreased by 37% (95% CI 11.5%-55.4%), from 199 (95% CI 160-248) cases/100,000 adults in 2007 to 125 (95% CI 98-159) cases/100,000 adults in 2017. Prevalence of smear-positive TB dropped by 53% (95% CI 27.0%-69.7%), from 99 (95% CI 78-125) cases/100,000 adults to 46 (95% CI 32-68) cases/100,000 adults; smear-negative TB showed no substantial decrease. Replacing microscopy with molecular methods for primary diagnostics might enhance diagnosis of pulmonary TB cases and further lower TB burden.

Baseline assessment of pharmacovigilance activities in four sub-Saharan African countries: a perspective on tuberculosis.

BACKGROUND: New medicines have become available for the treatment of drug-resistant tuberculosis (DR-TB) and are introduced in sub-Saharan Africa (SSA) by the national TB programs (NTPs) through special access schemes. Pharmacovigilance is typically the task of national medicines regulatory agencies (NMRAs), but the active drug safety monitoring and management (aDSM) recommended for the new TB medicines and regimens was introduced through the NTPs. We assessed the strengths and challenges of pharmacovigilance systems in Eswatini, Ethiopia, Nigeria and Tanzania, focusing on their capacity to monitor safety of medicines registered and not registered by the NMRAs for the treatment of DR-TB. METHODS: Assessment visits were conducted to all four countries by a multidisciplinary team. We used a pharmacovigilance indicator tool derived from existing tools, interviewed key stakeholders, and visited health facilities where DR-TB patients were treated with new medicines. Assessment results were verified with the local NMRAs and NTPs. RESULTS: Most countries have enabling laws, regulations and guidelines for the conduct of pharmacovigilance by the NMRAs. The relative success of NTP-NMRA collaboration is much influenced by interpersonal relationships between staff. Division of roles and responsibilities is not always clear and leads to duplication and unfulfilled tasks (e.g. causality assessment). The introduction of aDSM has increased awareness among DR-TB healthcare providers. CONCLUSION: aDSM has created awareness about the importance of pharmacovigilance among NTPs. In the future, a push for conducting pharmacovigilance through public health programs seems useful, but this needs to coincide with increased collaboration with between public health programs and NMRAs with clear formulation of roles and responsibilities.

Correction to: The use of ultrasensitive quantitative-PCR to assess the impact of primaquine on asymptomatic relapse of Plasmodium vivax infections: a randomized, controlled trial in Lao PDR.

Following publication of the original article [1], it was brought to the authors' attention that one of the names in the author list had been provided with the incorrect spelling.

The use of ultrasensitive quantitative-PCR to assess the impact of primaquine on asymptomatic relapse of Plasmodium vivax infections: a randomized, controlled trial in Lao PDR.

BACKGROUND: Trials to assess the efficacy of the radical cure of Plasmodium vivax malaria with 8-aminoquinolines require that most post-treatment relapses are identified, but there is no consensus on the optimal duration of follow-up in either symptomatic or asymptomatic vivax malaria. The efficacy of a 14-day course of primaquine on the cumulative incidence of recurrent asymptomatic P. vivax infections detected by ultrasensitive quantitative PCR (uPCR) as a primary endpoint was assessed. METHODS: A randomized, placebo-controlled, single-blind trial was conducted in four villages of the Lao PDR during 2016-2018 nested in a larger project evaluating mass drug administrations (MDA) with dihydroartemisinin-piperaquine (DP) and a single low-dose primaquine to clear Plasmodium falciparum infections. In the nested sub-study, eligible participants with mono- or mixed P. vivax infections detected by uPCR were randomized to receive either 14 days of primaquine (0.5 mg/kg/day) or placebo during the last round of MDA (round 3) through directly observed therapy. Participants were checked monthly for 12 months for parasitaemia using uPCR. The primary outcome was cumulative incidence of participants with at least one recurrent episode of P. vivax infection. RESULTS: 20 G6PD-normal participants were randomized in each arm. 5 (29%) of 20 participants in the placebo arm experienced asymptomatic, recurrent P. vivax infections, resulting in a cumulative incidence at month 12 of 29%. None of the 20 participants in the intervention arm had recurrent infections (p = 0.047 Fisher's exact test). Participants with recurrent P. vivax infections were found to be parasitaemic for between one and five sequential monthly tests. The median time to recurrence of P. vivax parasitaemia was 178 days (range 62-243 days). CONCLUSIONS: A 14-day course of primaquine in addition to a DP-MDA was safe, well-tolerated, and prevented recurrent asymptomatic P. vivax infections. Long follow-up for up to 12 months is required to capture all recurrences following the treatment of asymptomatic vivax infection. To eliminate all malarias in settings where P. vivax is endemic, a full-course of an 8-aminoquinolines should be added to MDA to eliminate all malarias. Trial registration This study was registered with ClinicalTrials.gov under NCT02802813 on 16th June 2016. https://clinicaltrials.gov/ct2/show/NCT02802813.

Value of pyrazinamide for composition of new treatment regimens for multidrug-resistant Mycobacterium tuberculosis in China.

BACKGROUND: Pyrazinamide still may be a useful drug for treatment of rifampin-resistant (RR-TB) or multidrug-resistant tuberculosis (MDR-TB) in China while awaiting scale up of new drugs and regimens including bedaquiline and linezolid. The level of pyrazinamide resistance among MDR-TB patients in China is not well established. Therefore, we assessed pyrazinamide resistance in a representative sample and explored determinants and patterns of pncA mutations. METHODS: MDR-TB isolates from the 2007 national drug resistance survey of China were sub-cultured and examined for pyrazinamide susceptibility by BACTEC MGIT 960 method. pncA mutations were identified by sequencing. Characteristics associated with pyrazinamide resistance were analyzed using univariable and multivariable log-binominal regression. RESULTS: Of 401 MDR-TB isolates, 324 were successfully sub-cultured and underwent drug susceptibility testing. Pyrazinamide resistance was prevalent in 40.7% of samples, similarly among new and previously treated MDR-TB patients. Pyrazinamide resistance in MDR-TB patients was associated with lower age (adjusted OR 0.54; 95% CI, 0.34-0.87 for those aged ≧60 years compared to < 40 years). Pyrazinamide resistance was not associated with gender, residential area, previous treatment history and Beijing genotype. Of 132 patients with pyrazinamide resistant MDR-TB, 97 (73.5%) had a mutation in the pncA gene; with 61 different point mutations causing amino acid change, and 11 frameshifts in the pncA gene. The mutations were scattered throughout the whole pncA gene and no hot spot region was identified. CONCLUSIONS: Pyrazinamide resistance among MDR-TB patients in China is common, although less so in elderly patients. Therefore, pyrazinamide should only be used for treatment of RR/MDR-TB in China if susceptibility is confirmed. Molecular testing for detection of pyrazinamide resistance only based on pncA mutations has certain value for the rapid detection of pyrazinamide resistance in MDR-TB strains but other gene mutations conferring to pyrazinamide resistance still need to be explored to increase its predictive ability .

Bioaerosol sampling of patients with suspected pulmonary tuberculosis: a study protocol.

BACKGROUND: Tuberculosis (TB) is transmitted in bioaerosols containing Mycobacterium tuberculosis (Mtb). Despite being central to ongoing TB transmission, no routine diagnostic assay exists to measure Mtb in bioaerosols. Furthermore, published studies of Mtb in bioaerosol samples have been limited to individuals with sputum-positive pulmonary TB. Notably, TB diagnosis is based on clinical symptoms and sputum laboratory findings. This is despite the fact that approximately half of all patients commencing TB treatment are sputum-negative, resulting in a high proportion of presumptive treatments. Here, we propose to use a sensitive air sampling protocol to investigate the prevalence of Mtb-containing bioaerosols in both sputum-positive and sputum-negative TB suspects, at the same time evaluating the potential to identify unrecognized transmitters of TB. METHODS: Our parallel-group design will identify viable Mtb in bioaerosols produced by individuals attending a TB clinic in South Africa. Sampling will be performed on eligible individuals presenting with symptoms indicative of TB and repeated at 14 days if initially positive. Participants will be prospectively classified into three distinct groups based on National TB Control Program (NTBCP) criteria: Group A, TB notification with sputum-based laboratory confirmation; Group B, TB notification with empiric diagnosis; and Group C, individuals not notified. Group C individuals with detectable Mtb bioaerosol will be monitored until resolution of clinical and laboratory status. Collection of bioaerosol specimens will be via two consecutive sampling modalities: (1) direct sampling following a specific respiratory manoeuvre; and (2) indirect sampling during passive respiratory activity. Bioaerosol specimens will be analyzed for viable Mtb using DMN-trehalose staining and live-cell fluorescence microscopy. Mtb genomes and mycobacterial and host lipids will be detected using droplet digital PCR and mass spectrometry analyses, respectively. The primary objective is to determine the prevalence of Mtb bioaerosols in all TB clinic attendees and in each of the groups. Secondary objectives are to investigate differences in prevalence of Mtb bioaerosol by HIV status and current isoniazid preventive therapy (IPT) use; we will also determine the impact of anti-TB chemotherapy on Mtb-containing bioaerosol production. DISCUSSION: Respiratory bioaerosol has a potential role in non-invasive TB diagnosis, infectivity measurement and treatment monitoring. TRIAL REGISTRATION: ClinicalTrials.gov: NCT04241809 . Date of Registration: 27/1/2020.