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 distributional outcomes of rights-based management in fisheries.

Fisheries managers have increasingly adopted rights-based management (i.e., "catch shares" or "individual transferable quotas" [ITQs]) to address economic and biological management challenges under prior governance regimes. Despite their ability to resolve some of the symptoms of the tragedy of the commons and improve economic efficiency, catch shares remain controversial for their potentially disruptive social effects. One criticism is that the benefits of rights-based reforms are unequally distributed across vessels and between fishery participants (e.g., crew and hired captains) and that stakeholders that do not receive an allocation of harvest rights may see their remuneration decrease. Yet, empirically assessing these claims is difficult in almost all ITQs due to poor availability of longitudinal cost, earnings, and employment data. This paper evaluates these claims using vessel-level data to characterize impacts of a long-established ITQ program for Alaskan crab fisheries on the level and distribution of payments to claimant groups. We find that the share of vessel proceeds accruing to captains, crew, and vessel owners declined under the catch-share regime to make room for new payments to quota owners. Average daily payments to captains, crew, and vessel owners declined, albeit slightly, yet retained their pre-ITQ premia relative to compensation in other sectors. However, inequality in payments to workers and vessel owners declined after ITQs, as did the interseasonal volatility in compensation to workers, a measure of financial risk. Finally, we find that consolidation-induced increases in leasing costs have had little effect on workers' remuneration, but have reduced returns to vessel ownership.

Individualistic culture increases economic mobility in the United States.

Where an individual grows up has large implications for their long-term economic outcomes, including earnings and intergenerational mobility. Even within the United States, the "causal effect of place" varies greatly and cannot be fully explained by socioeconomic conditions. Across different nations, variation in growth and mobility have been linked to more individualistic cultures. We assess how variation of historically driven individualism within the United States affects mobility. Areas in the United States that were isolated on the frontier for longer periods of time during the 19th century have a stronger culture of "rugged individualism" [S. Bazzi, M. Fiszbein, M. Gebresilasse, Econometrica 88, 2329-2368 (2020)]. We combine county-level measures of frontier experience with modern measures of the causal effect of place on mobility-the predicted percentage change in an individual's earnings at age 26 y associated with "growing up" in a particular county [R. Chetty, N. Hendren, Q. J. Econ. 133, 1163-1228 (2018)]. Using commuting zone fixed effects and a suite of county-level controls to absorb regional variation in frontier experience and modern economic conditions, we find an additional decade of frontier experience results in 25% greater modern-day income mobility for children of parents in the 25th percentile of income and 14% for those born to parents in the 75th percentile. We use mediation analysis to present suggestive evidence that informal manifestations of "rugged individualism"-those embodied by the individuals themselves-are more strongly associated with upward mobility than formal policy or selective migration.

Capture and visualization of live Mycobacterium tuberculosis bacilli from tuberculosis patient bioaerosols.

Interrupting transmission is an attractive anti-tuberculosis (TB) strategy but it remains underexplored owing to our poor understanding of the events surrounding transfer of Mycobacterium tuberculosis (Mtb) between hosts. Determining when live, infectious Mtb bacilli are released and by whom has proven especially challenging. Consequently, transmission chains are inferred only retrospectively, when new cases are diagnosed. This process, which relies on molecular analyses of Mtb isolates for epidemiological fingerprinting, is confounded by the prolonged infectious period of TB and the potential for transmission from transient exposures. We developed a Respiratory Aerosol Sampling Chamber (RASC) equipped with high-efficiency filtration and sampling technologies for liquid-capture of all particulate matter (including Mtb) released during respiration and non-induced cough. Combining the mycobacterial cell wall probe, DMN-trehalose, with fluorescence microscopy of RASC-captured bioaerosols, we detected and quantified putative live Mtb bacilli in bioaerosol samples arrayed in nanowell devices. The RASC enabled non-invasive capture and isolation of viable Mtb from bioaerosol within 24 hours of collection. A median 14 live Mtb bacilli (range 0-36) were isolated in single-cell format from 90% of confirmed TB patients following 60 minutes bioaerosol sampling. This represented a significant increase over previous estimates of transmission potential, implying that many more organisms might be released daily than commonly assumed. Moreover, variations in DMN-trehalose incorporation profiles suggested metabolic heterogeneity in aerosolized Mtb. Finally, preliminary analyses indicated the capacity for serial image capture and analysis of nanowell-arrayed bacilli for periods extending into weeks. These observations support the application of this technology to longstanding questions in TB transmission including the propensity for asymptomatic transmission, the impact of TB treatment on Mtb bioaerosol release, and the physiological state of aerosolized bacilli.

Aerosolization of Mycobacterium tuberculosis by Tidal Breathing.

Rationale: Interrupting tuberculosis (TB) transmission requires an improved understanding of how and when the causative organism, Mycobacterium tuberculosis (Mtb), is aerosolized. Although cough is commonly assumed to be the dominant source of Mtb aerosols, recent evidence of cough-independent Mtb release implies the contribution of alternative mechanisms. Objectives: To compare the aerosolization of Mtb bacilli and total particulate matter from patients with TB during three separate respiratory maneuvers: tidal breathing (TiBr), FVC, and cough. Methods: Bioaerosol sampling and Mtb enumeration by live-cell, fluorescence microscopy were combined with real-time measurement of CO2 concentration and total particle counts from 38 patients with GeneXpert-positive TB before treatment initiation. Measurements and Main Results: For all maneuvers, the proportions of particles detected across five size categories were similar, with most particles falling between 0.5-5 µm. Although total particle counts were 4.8-fold greater in cough samples than either TiBr or FVC, all three maneuvers returned similar rates of positivity for Mtb. No correlation was observed between total particle production and Mtb count. Instead, for total Mtb counts, the variability between individuals was greater than the variability between sampling maneuvers. Finally, when modelled using 24-hour breath and cough frequencies, our data indicate that TiBr might contribute more than 90% of the daily aerosolized Mtb among symptomatic patients with TB. Conclusions: Assuming the number of viable Mtb organisms released offers a reliable proxy of patient infectiousness, our observations imply that TiBr and interindividual variability in Mtb release might be significant contributors to TB transmission among active cases.

Targeted Gene Expression Profiling of Human Myeloid Cells From Blood and Lung Compartments of Patients With Tuberculosis and Other Lung Diseases.

Myeloid-derived suppressor cells (MDSC) have been identified in the peripheral blood and granulomas of patients with active TB disease, but their phenotype-, function-, and immunosuppressive mechanism- spectrum remains unclear. Importantly, the frequency and signaling pathways of MDSC at the site of disease is unknown with no indication how this compares to MDSC identified in peripheral blood or to those of related myeloid counterparts such as alveolar macrophages and monocytes. Most phenotypic and functional markers have been described in oncological studies but have not yet been validated in TB. Using a panel of 43 genes selected from pathways previously shown to contribute to tumor-derived MDSC, we set out to evaluate if the expression of these additional functional markers and properties may also be relevant to TB-derived MDSC. Differential expression was investigated between MDSC, alveolar macrophages and monocytes enriched from bronchoalveolar lavage fluid and peripheral blood of patients with active TB, patients with other lung diseases (OLD). Results demonstrated that anatomical compartments may drive compartment-specific immunological responses and subsequent MDSC immunosuppressive functions, demonstrated by the observation that MDSC and/or monocytes from PB alone can discriminate, via hierarchical clustering, between patients with active TB disease and OLD. Our data show that the gene expression patterns of MDSC in peripheral blood and bronchoalveolar lavage fluid do not cluster according to disease states (TB vs OLD). This suggests that MDSC from TB patients may display similar gene expression profiles to those found for MDSC in cancer, but this needs to be validated in a larger cohort. These are important observations for TB research and may provide direction for future studies aimed at repurposing and validating cancer immunotherapies for use in TB.

Cough-independent production of viable Mycobacterium tuberculosis in bioaerosol.

BACKGROUND: Symptoms of infectious respiratory illnesses are often assumed to drive transmission. However, production and release of Mycobacterium tuberculosis (Mtb) bioaerosols is poorly understood. We report quantitation of Mtb exhaled during specific respiratory manoeuvres. METHODS: Direct capture of nascent bioaerosol particles and indirect collection of aged particles was performed in 10 healthy subjects. Indirect and direct capture of exhaled viable Mtb bacilli was compared in 38 PTB patients and directly captured viable Mtb during cough and bronchiole-burst manoeuvres in 27 of the PTB patients. RESULTS: Direct sampling of healthy subjects captured larger bioaerosol volumes with higher proportions of 2-5 µm particles than indirect sampling. Indirect sampling identified viable Mtb in 92.1% (35 of 38) of PTB patients during 60-min relaxed breathing, median bacillary count 7.5 (IQR: 3.25-19). Direct sampling for 10-min identified Mtb in 97.4% (37 of 38) of PTB patients with higher bacilli counts (p < 0.001), median 24.5 (IQR:11.25-37.5). A short 5-min sampling regimen of 10 coughs or 10 bronchiole-burst manoeuvres yielded a median of 11 (IQR: 4-17) and 11 (IQR: 7-17.5) Mtb bacilli, respectively (p = 0.53). CONCLUSIONS: Peripheral lung bioaerosol released through deep exhalations alone contained viable Mtb suggesting non-cough transmission is possible in PTB.