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Havumaki J, Warren JL, Zelner J, Menzies NA, Calderon R, Contreras C, Lecca L, Becerra MC, Murray M, Cohen T. Spatially-targeted tuberculosis screening has limited impact beyond household contact tracing in Lima, Peru: A model-based analysis. PLoS One 2023; 18:e0293519. [PMID: 37903091 PMCID: PMC10615320 DOI: 10.1371/journal.pone.0293519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 10/15/2023] [Indexed: 11/01/2023] Open
Abstract
Mathematical models have suggested that spatially-targeted screening interventions for tuberculosis may efficiently accelerate disease control, but empirical data supporting these findings are limited. Previous models demonstrating substantial impacts of these interventions have typically simulated large-scale screening efforts and have not attempted to capture the spatial distribution of tuberculosis in households and communities at a high resolution. Here, we calibrate an individual-based model to the locations of case notifications in one district of Lima, Peru. We estimate the incremental efficiency and impact of a spatially-targeted interventions used in combination with household contact tracing (HHCT). Our analysis reveals that HHCT is relatively efficient with a median of 40 (Interquartile Range: 31.7 to 49.9) household contacts required to be screened to detect a single case of active tuberculosis. However, HHCT has limited population impact, producing a median incidence reduction of only 3.7% (Interquartile Range: 5.8% to 1.9%) over 5 years. In comparison, spatially targeted screening (which we modeled as active case finding within high tuberculosis prevalence areas 100 m2 grid cell) is far less efficient, requiring evaluation of ≈12 times the number of individuals as HHCT to find a single individual with active tuberculosis. Furthermore, the addition of the spatially targeted screening effort produced only modest additional reductions in tuberculosis incidence over the 5 year period (≈1.3%) in tuberculosis incidence. In summary, we found that HHCT is an efficient approach for tuberculosis case finding, but has limited population impact. Other screening approaches which target areas of high tuberculosis prevalence are less efficient, and may have limited impact unless very large numbers of individuals can be screened.
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Affiliation(s)
- Joshua Havumaki
- Department of Epidemiology of Microbial Diseases, Yale University, New Haven, CT, United States of America
| | - Joshua L. Warren
- Department of Biostatistics, Yale School of Public Health, New Haven, CT, United States of America
| | - Jon Zelner
- Department of Epidemiology, University of Michigan, Ann Arbor, MI, United States of America
- Center for Social Epidemiology and Population Health, University of Michigan School of Public Health, Ann Arbor, MI, United States of America
| | - Nicolas A. Menzies
- Department of Global Health and Population, Harvard T. H. Chan, School of Public Health, Boston, MA, United States of America
| | - Roger Calderon
- Socios en Salud Sucursal Peru, Lima, Peru
- Programa Acadêmico de Tuberculose, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Leonid Lecca
- Department of Global Health and Population, Harvard T. H. Chan, School of Public Health, Boston, MA, United States of America
- Socios en Salud Sucursal Peru, Lima, Peru
| | - Mercedes C. Becerra
- Department of Global Health and Population, Harvard T. H. Chan, School of Public Health, Boston, MA, United States of America
| | - Megan Murray
- Department of Global Health and Population, Harvard T. H. Chan, School of Public Health, Boston, MA, United States of America
| | - Ted Cohen
- Department of Epidemiology of Microbial Diseases, Yale University, New Haven, CT, United States of America
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Horsburgh CR, Jo Y, Nichols B, Jenkins HE, Russell CA, White LF. Contribution of Reinfection to Annual Rate of Tuberculosis Infection (ARI) and Incidence of Tuberculosis Disease. Clin Infect Dis 2023; 76:e965-e972. [PMID: 35666515 PMCID: PMC10169390 DOI: 10.1093/cid/ciac451] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 05/24/2022] [Accepted: 06/01/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Modeling studies have concluded that 60-80% of tuberculosis (TB) infections result from reinfection of previously infected persons. The annual rate of infection (ARI), a standard measure of the risk of TB infection in a community, may not accurately reflect the true risk of infection among previously infected persons. We constructed a model of infection and reinfection with Mycobacterium tuberculosis to explore the predictive accuracy of ARI and its effect on disease incidence. METHODS We created a deterministic simulation of the progression from TB infection to disease and simulated the prevalence of TB infection at the beginning and end of a theoretical year of infection. We considered 10 disease prevalence scenarios ranging from 100/100 000 to 1000/100 000 in simulations where TB exposure probability was homogeneous across the whole simulated population or heterogeneously stratified into high-risk and low-risk groups. ARI values, rates of progression from infection to disease, and the effect of multiple reinfections were obtained from published studies. RESULTS With homogeneous exposure risk, observed ARI values produced expected numbers of infections. However, when heterogeneous risk was introduced, observed ARI was seen to underestimate true ARI by 25-58%. Of the cases of TB disease that occurred, 36% were among previously infected persons when prevalence was 100/100 000, increasing to 79% of cases when prevalence was 1000/100 000. CONCLUSIONS Measured ARI underestimates true ARI as a result of heterogeneous population mixing. The true force of infection in a community may be greater than previously appreciated. Hyperendemic communities likely contribute disproportionally to the global TB disease burden.
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Affiliation(s)
- C Robert Horsburgh
- Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
- Department of Global Health, Boston University School of Public Health, Boston, Massachusetts, USA
- Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts, USA
| | - Youngji Jo
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Brooke Nichols
- Department of Global Health, Boston University School of Public Health, Boston, Massachusetts, USA
| | - Helen E Jenkins
- Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts, USA
| | - Colin A Russell
- Department of Global Health, Boston University School of Public Health, Boston, Massachusetts, USA
- Department of Medical Microbiology, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Laura F White
- Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts, USA
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3
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Joslyn LR, Flynn JL, Kirschner DE, Linderman JJ. Concomitant immunity to M. tuberculosis infection. Sci Rep 2022; 12:20731. [PMID: 36456599 PMCID: PMC9713124 DOI: 10.1038/s41598-022-24516-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 11/16/2022] [Indexed: 12/02/2022] Open
Abstract
Some persistent infections provide a level of immunity that protects against reinfection with the same pathogen, a process referred to as concomitant immunity. To explore the phenomenon of concomitant immunity during Mycobacterium tuberculosis infection, we utilized HostSim, a previously published virtual host model of the immune response following Mtb infection. By simulating reinfection scenarios and comparing with data from non-human primate studies, we propose a hypothesis that the durability of a concomitant immune response against Mtb is intrinsically tied to levels of tissue resident memory T cells (Trms) during primary infection, with a secondary but important role for circulating Mtb-specific T cells. Further, we compare HostSim reinfection experiments to observational TB studies from the pre-antibiotic era to predict that the upper bound of the lifespan of resident memory T cells in human lung tissue is likely 2-3 years. To the authors' knowledge, this is the first estimate of resident memory T-cell lifespan in humans. Our findings are a first step towards demonstrating the important role of Trms in preventing disease and suggest that the induction of lung Trms is likely critical for vaccine success.
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Affiliation(s)
- Louis R. Joslyn
- grid.214458.e0000000086837370Department of Chemical Engineering, University of Michigan, G045W NCRC B28, 2800 Plymouth Rd, Ann Arbor, MI 48109-2136 USA ,grid.214458.e0000000086837370Department of Microbiology and Immunology, University of Michigan Medical School, 1150W Medical Center Drive, 5641 Medical Science II, Ann Arbor, MI 48109-5620 USA
| | - JoAnne L. Flynn
- grid.21925.3d0000 0004 1936 9000Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261 USA
| | - Denise E. Kirschner
- grid.214458.e0000000086837370Department of Microbiology and Immunology, University of Michigan Medical School, 1150W Medical Center Drive, 5641 Medical Science II, Ann Arbor, MI 48109-5620 USA
| | - Jennifer J. Linderman
- grid.214458.e0000000086837370Department of Chemical Engineering, University of Michigan, G045W NCRC B28, 2800 Plymouth Rd, Ann Arbor, MI 48109-2136 USA
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4
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Leavitt SV, Jenkins HE, Sebastiani P, Lee RS, Horsburgh CR, Tibbs AM, White LF. Estimation of the generation interval using pairwise relative transmission probabilities. Biostatistics 2022; 23:807-824. [PMID: 33527996 PMCID: PMC9291635 DOI: 10.1093/biostatistics/kxaa059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 11/13/2022] Open
Abstract
The generation interval (the time between infection of primary and secondary cases) and its often used proxy, the serial interval (the time between symptom onset of primary and secondary cases) are critical parameters in understanding infectious disease dynamics. Because it is difficult to determine who infected whom, these important outbreak characteristics are not well understood for many diseases. We present a novel method for estimating transmission intervals using surveillance or outbreak investigation data that, unlike existing methods, does not require a contact tracing data or pathogen whole genome sequence data on all cases. We start with an expectation maximization algorithm and incorporate relative transmission probabilities with noise reduction. We use simulations to show that our method can accurately estimate the generation interval distribution for diseases with different reproductive numbers, generation intervals, and mutation rates. We then apply our method to routinely collected surveillance data from Massachusetts (2010-2016) to estimate the serial interval of tuberculosis in this setting.
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Affiliation(s)
- Sarah V Leavitt
- Department of Biostatistics, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; Epidemiology Division, University of Toronto Dalla Lana School of Public Health, 155 College St Room 500, Toronto, ON M5T 3M7, Canada; Department of Epidemiology, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; and Massachusetts Department of Public Health, 250 Washington St, Boston, MA 02108
| | - Helen E Jenkins
- Department of Biostatistics, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; Epidemiology Division, University of Toronto Dalla Lana School of Public Health, 155 College St Room 500, Toronto, ON M5T 3M7, Canada; Department of Epidemiology, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; and Massachusetts Department of Public Health, 250 Washington St, Boston, MA 02108
| | - Paola Sebastiani
- Department of Biostatistics, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; Epidemiology Division, University of Toronto Dalla Lana School of Public Health, 155 College St Room 500, Toronto, ON M5T 3M7, Canada; Department of Epidemiology, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; and Massachusetts Department of Public Health, 250 Washington St, Boston, MA 02108
| | - Robyn S Lee
- Department of Biostatistics, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; Epidemiology Division, University of Toronto Dalla Lana School of Public Health, 155 College St Room 500, Toronto, ON M5T 3M7, Canada; Department of Epidemiology, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; and Massachusetts Department of Public Health, 250 Washington St, Boston, MA 02108
| | - C Robert Horsburgh
- Department of Biostatistics, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; Epidemiology Division, University of Toronto Dalla Lana School of Public Health, 155 College St Room 500, Toronto, ON M5T 3M7, Canada; Department of Epidemiology, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; and Massachusetts Department of Public Health, 250 Washington St, Boston, MA 02108
| | - Andrew M Tibbs
- Department of Biostatistics, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; Epidemiology Division, University of Toronto Dalla Lana School of Public Health, 155 College St Room 500, Toronto, ON M5T 3M7, Canada; Department of Epidemiology, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; and Massachusetts Department of Public Health, 250 Washington St, Boston, MA 02108
| | - Laura F White
- Department of Biostatistics, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; Epidemiology Division, University of Toronto Dalla Lana School of Public Health, 155 College St Room 500, Toronto, ON M5T 3M7, Canada; Department of Epidemiology, Boston University School of Public Health, 801 Massachusetts Ave, Boston, MA 02118; and Massachusetts Department of Public Health, 250 Washington St, Boston, MA 02108
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Diaz MM, Zacarías MG, Sotolongo P, Sanes MF, Franklin DJ, Marquine MJ, Cherner M, Cárcamo C, Ellis RJ, Lanata S, García PJ. Characterization of HIV-Associated Neurocognitive Impairment in Middle-Aged and Older Persons With HIV in Lima, Peru. Front Neurol 2021; 12:629257. [PMID: 34220665 PMCID: PMC8248346 DOI: 10.3389/fneur.2021.629257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 04/21/2021] [Indexed: 12/12/2022] Open
Abstract
Background: With widespread use of antiretroviral medications, people living with HIV (PWH) are living longer worldwide, increasing their risk of developing neurocognitive impairment (NCI). The proportion of Peruvians over age 60 is expected to increase to 25% of the population by 2050, including PWH. Therefore, the problem of aging and NCI, especially in the setting of HIV infection, is uniquely pressing. We sought to study the rates of and risk factors associated with NCI among middle-aged and older PWH in Lima, Peru. Materials and Methods: Sociodemographic, medical (infectious and non-infectious), and psychiatric comorbidity and laboratory data were collected. We administered a brief neuropsychological battery evaluating seven cognitive domains affected in HIV-associated NCI and a depression screening. Cognitive test raw scores were converted to T-scores that were demographically adjusted. Descriptive statistics were performed together with regression (unadjusted and adjusted) analyses to determine potential risk factors for NCI among PWH. Results: This was a cross-sectional study in which 144 PWH aged ≥40 years attending a large HIV clinic in Lima, Peru, were recruited from September 2019 to March 2020. Mean age was 51.6 ± 7.7 years, and mean years of education were 14.0 ± 3.1 with 15% females. Median [interquartile range (IQR)] current CD4 and nadir CD4 were 554 (371, 723) and 179 (83, 291), respectively, and 10% currently had AIDS. The prevalence of NCI was 28.5%, and many demonstrated difficulty with attention and working memory (70%). One-quarter of PWH had mild depression or worse on Patient Health Questionnaire 9 (PHQ-9 ≥ 5). In bivariate analyses, neither a depression history nor a higher PHQ-9 score correlated with NCI. No other non-communicable medical or psychiatric comorbidity nor HIV characteristic was predictive of NCI. Having a positive lifetime history of hepatitis B infection, pulmonary tuberculosis, or syphilis increased risk of NCI (PR 1.72; 95% CI 1.04-2.86) in unadjusted analyses, but not in adjusted analyses. Conclusions: NCI among older Peruvians with HIV was found to be highly prevalent with levels consistent with prior reports of HIV-associated NCI worldwide. Common latent HIV-associated co-infections, including latent syphilis, hepatitis B infection, or pulmonary tuberculosis, may increase the risk of NCI among middle-aged and older PWH in Peru.
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Affiliation(s)
- Monica M. Diaz
- Department of Medicine, University of California, San Diego, San Diego, CA, United States
- University of California Global Health Institute, San Diego, CA, United States
- Facultad de Salud Pública, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Marcela Gil Zacarías
- Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Patricia Sotolongo
- Department of Psychology, Jackson Memorial Hospital, Miami, FL, United States
| | - María F. Sanes
- Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Donald J. Franklin
- Human Immunodeficiency Virus (HIV) Neurobehavioral Research Center, University of California, San Diego, San Diego, CA, United States
- Department of Psychiatry, University of California, San Diego, San Diego, CA, United States
| | - María J. Marquine
- Human Immunodeficiency Virus (HIV) Neurobehavioral Research Center, University of California, San Diego, San Diego, CA, United States
- Department of Psychiatry, University of California, San Diego, San Diego, CA, United States
| | - Mariana Cherner
- Human Immunodeficiency Virus (HIV) Neurobehavioral Research Center, University of California, San Diego, San Diego, CA, United States
- Department of Psychiatry, University of California, San Diego, San Diego, CA, United States
| | - Cesar Cárcamo
- Facultad de Salud Pública, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Ronald J. Ellis
- Human Immunodeficiency Virus (HIV) Neurobehavioral Research Center, University of California, San Diego, San Diego, CA, United States
- Department of Neurosciences, University of California, San Diego, San Diego, CA, United States
| | - Serggio Lanata
- Weill Institute for Neurosciences, Memory and Aging Center, University of California, San Francisco, San Francisco, CA, United States
- Global Brain Health Institute, University of California, San Francisco, San Francisco, CA, United States
| | - Patricia J. García
- Facultad de Salud Pública, Universidad Peruana Cayetano Heredia, Lima, Peru
- School of Public Health, University of Washington, Seattle, WA, United States
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6
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McQuaid CF, Vassall A, Cohen T, Fiekert K, White RG. The impact of COVID-19 on TB: a review of the data. Int J Tuberc Lung Dis 2021; 25:436-446. [PMID: 34049605 PMCID: PMC8171247 DOI: 10.5588/ijtld.21.0148] [Citation(s) in RCA: 136] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 03/23/2021] [Indexed: 12/12/2022] Open
Abstract
Early in the COVID-19 pandemic, models predicted hundreds of thousands of additional TB deaths as a result of health service disruption. To date, empirical evidence on the effects of COVID-19 on TB outcomes has been limited. Here we summarise the evidence available at a country level, identifying broad mechanisms by which COVID-19 may modify TB burden and mitigation efforts. From the data, it is clear that there have been substantial disruptions to TB health services and an increase in vulnerability to TB. Evidence for changes in Mycobacterium tuberculosis transmission is limited, and it remains unclear how the resources required and available for the TB response have changed. To advocate for additional funding to mitigate the impact of COVID-19 on the global TB burden, and to efficiently allocate resources for the TB response, requires a significant improvement in the TB data available.
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Affiliation(s)
- C F McQuaid
- TB Modelling Group, TB Centre and Centre for Mathematical Modelling of Infectious Diseases, Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine (LSHTM), London, UK
| | - A Vassall
- Department of Global Health Development, Faculty of Public Health and Policy, LSHTM, London, UK
| | - T Cohen
- Yale School of Public Health, Laboratory of Epidemiology and Public Health, New Haven, CT, USA
| | - K Fiekert
- KNCV Tuberculosefonds, The Hague, the Netherlands
| | - R G White
- TB Modelling Group, TB Centre and Centre for Mathematical Modelling of Infectious Diseases, Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine (LSHTM), London, UK
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7
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Leavitt SV, Lee RS, Sebastiani P, Horsburgh CR, Jenkins HE, White LF. Estimating the relative probability of direct transmission between infectious disease patients. Int J Epidemiol 2021; 49:764-775. [PMID: 32211747 DOI: 10.1093/ije/dyaa031] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 02/07/2020] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Estimating infectious disease parameters such as the serial interval (time between symptom onset in primary and secondary cases) and reproductive number (average number of secondary cases produced by a primary case) are important in understanding infectious disease dynamics. Many estimation methods require linking cases by direct transmission, a difficult task for most diseases. METHODS Using a subset of cases with detailed genetic and/or contact investigation data to develop a training set of probable transmission events, we build a model to estimate the relative transmission probability for all case-pairs from demographic, spatial and clinical data. Our method is based on naive Bayes, a machine learning classification algorithm which uses the observed frequencies in the training dataset to estimate the probability that a pair is linked given a set of covariates. RESULTS In simulations, we find that the probabilities estimated using genetic distance between cases to define training transmission events are able to distinguish between truly linked and unlinked pairs with high accuracy (area under the receiver operating curve value of 95%). Additionally, only a subset of the cases, 10-50% depending on sample size, need to have detailed genetic data for our method to perform well. We show how these probabilities can be used to estimate the average effective reproductive number and apply our method to a tuberculosis outbreak in Hamburg, Germany. CONCLUSIONS Our method is a novel way to infer transmission dynamics in any dataset when only a subset of cases has rich contact investigation and/or genetic data.
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Affiliation(s)
- Sarah V Leavitt
- School of Public Health, Department of Biostatistics, Boston University, Boston, MA, USA
| | - Robyn S Lee
- Harvard T.H. Chan School of Public Health, Boston, MA, USA.,University of Toronto Dalla Lana School of Public Health Epidemiology Division, Toronto, ON, Canada
| | - Paola Sebastiani
- School of Public Health, Department of Biostatistics, Boston University, Boston, MA, USA
| | - C Robert Horsburgh
- School of Public Health, Department of Epidemiology, Boston University, Boston, MA, USA
| | - Helen E Jenkins
- School of Public Health, Department of Biostatistics, Boston University, Boston, MA, USA
| | - Laura F White
- School of Public Health, Department of Biostatistics, Boston University, Boston, MA, USA
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8
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Transmission Modeling with Regression Adjustment for Analyzing Household-based Studies of Infectious Disease: Application to Tuberculosis. Epidemiology 2021; 31:238-247. [PMID: 31764276 DOI: 10.1097/ede.0000000000001143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Household contacts of people infected with a transmissible disease may be at risk due to this proximate exposure, or from other unobserved sources. Understanding variation in infection risk is essential for targeting interventions. METHODS We develop an analytical approach to estimate household and exogenous forces of infection, while accounting for individual-level characteristics that affect susceptibility to disease and transmissibility. We apply this approach to a cohort study conducted in Lima, Peru, of 18,544 subjects in 4,500 households with at least one active tuberculosis (TB) case and compare the results to those obtained by Poisson and logistic regression. RESULTS HIV-coinfected (susceptibility hazard ratio [SHR] = 3.80, 1.56-9.29), child (SHR = 1.72, 1.32-2.23), and teenage (SHR = 2.00, 1.49-2.68) household contacts of TB cases experience a higher hazard of TB than do adult contacts. Isoniazid preventive therapy (SHR = 0.30, 0.21-0.42) and Bacillus Calmette-Guérin (BCG) vaccination (SHR = 0.66, 0.51-0.86) reduce the risk of disease among household contacts. TB cases without microbiological confirmation exert a smaller hazard of TB among their close contacts compared with smear- or culture-positive cases (excess hazard ratio = 0.88, 0.82-0.93 for HIV- cases and 0.82, 0.57-0.94 for HIV+ cases). The extra household force of infection results in 0.01 (95% confidence interval [CI] = 0.004, 0.028) TB cases per susceptible household contact per year and the rate of transmission between a microbiologically confirmed TB case and susceptible household contact at 0.08 (95% CI = 0.045, 0.129) TB cases per pair per year. CONCLUSIONS Accounting for exposure to infected household contacts permits estimation of risk factors for disease susceptibility and transmissibility and comparison of within-household and exogenous forces of infection.
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9
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Ma Y, Jenkins HE, Sebastiani P, Ellner JJ, Jones-López EC, Dietze R, Horsburgh, Jr. CR, White LF. Using Cure Models to Estimate the Serial Interval of Tuberculosis With Limited Follow-up. Am J Epidemiol 2020; 189:1421-1426. [PMID: 32458995 PMCID: PMC7731991 DOI: 10.1093/aje/kwaa090] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/14/2020] [Accepted: 05/15/2020] [Indexed: 12/26/2022] Open
Abstract
Serial interval (SI), defined as the time between symptom onset in an infector and infectee pair, is commonly used to understand infectious diseases transmission. Slow progression to active disease, as well as the small percentage of individuals who will eventually develop active disease, complicate the estimation of the SI for tuberculosis (TB). In this paper, we showed via simulation studies that when there is credible information on the percentage of those who will develop TB disease following infection, a cure model, first introduced by Boag in 1949, should be used to estimate the SI for TB. This model includes a parameter in the likelihood function to account for the study population being composed of those who will have the event of interest and those who will never have the event. We estimated the SI for TB to be approximately 0.5 years for the United States and Canada (January 2002 to December 2006) and approximately 2.0 years for Brazil (March 2008 to June 2012), which might imply a higher occurrence of reinfection TB in a developing country like Brazil.
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Affiliation(s)
- Yicheng Ma
- Correspondence to Dr. Yicheng Ma, Department of Biostatistics, 801 Massachusetts Avenue, Boston, MA 02118 (e-mail: )
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10
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Bueno de Mesquita PJ, Noakes CJ, Milton DK. Quantitative aerobiologic analysis of an influenza human challenge-transmission trial. INDOOR AIR 2020; 30:1189-1198. [PMID: 32542890 PMCID: PMC7687273 DOI: 10.1111/ina.12701] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/20/2020] [Accepted: 05/26/2020] [Indexed: 05/05/2023]
Abstract
Despite evidence that airborne transmission contributes to influenza epidemics, limited knowledge of the infectiousness of human influenza cases hinders pandemic preparedness. We used airborne viral source strength and indoor CO2 monitoring from the largest human influenza challenge-transmission trial (EMIT: Evaluating Modes of Influenza Transmission, ClinicalTrials.gov number NCT01710111) to compute an airborne infectious dose generation rate q = 0.11 (95% CI 0.088, 0.12)/h and calculate the quantity of airborne virus per infectious dose σ = 1.4E + 5 RNA copies/quantum (95% CI 9.9E + 4, 1.8E + 5). We then compared these calculated values to available data on influenza airborne infectious dose from several previous studies, and applied the values to dormitory room environments to predict probability of transmission between roommates. Transmission risk from typical, moderately to severely symptomatic influenza cases is dramatically decreased by exposure reduction via increasing indoor air ventilation. The minority of cases who shed the most virus (ie, supershedders) may pose great risk even in well-ventilated spaces. Our modeling method and estimated infectiousness provide a ground work for (a) epidemiologic studies of transmission in non-experimental settings and (b) evaluation of the extent to which airborne exposure control strategies could limit transmission risk.
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Affiliation(s)
| | | | - Donald K. Milton
- Maryland Institute for Applied Environmental HealthUniversity of MarylandCollege ParkMarylandUSA
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11
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Coit J, Mendoza M, Pinedo C, Marin H, Chiang SS, Lecca L, Franke M. Performance of a household tuberculosis exposure survey among children in a Latin American setting. Int J Tuberc Lung Dis 2020; 23:1223-1227. [PMID: 31718760 DOI: 10.5588/ijtld.18.0841] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE: To evaluate the performance of a survey that quantifies the intensity of household tuberculosis (TB) exposure among children.METHODS: Children aged 0-14 years in Lima, Peru, with ≥1 signs and/or symptoms of TB and a history of contact with an adult TB patient were included. The 10-question survey was administered to caregivers and addressed sleep proximity, frequency of exposure, and infectiousness of the contact. Infection status was determined using tuberculin skin tests (TSTs). The exposure scale was evaluated for association with TST positivity using mixed-effects regression analyses.RESULTS: The exposure score was significantly associated with TST positivity (age-adjusted odds ratio [aOR] 1.14, 95%CI 1.02-1.28). We observed a stronger association with TST positivity in children aged ≤5 years; (aOR 1.23, 95%CI 1.07-1.41) and no association in children 6-14 years of age (aOR 0.99, 95%CI 0.82-1.20).CONCLUSION: This survey was easy to use and modestly successful in predicting TST positivity in children aged ≤5 years. It may be a useful resource for clinicians for diagnosing TB in children, and for national TB programs aiming to scale up preventive therapy initiatives.
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Affiliation(s)
- J Coit
- Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA, USA
| | - M Mendoza
- Socios En Salud, Sucursal Perú, Lima, Peru
| | - C Pinedo
- Socios En Salud, Sucursal Perú, Lima, Peru
| | - H Marin
- Socios En Salud, Sucursal Perú, Lima, Peru
| | - S S Chiang
- Department of Pediatrics, Alpert Medical School of Brown University, Providence, RI, Center for International Health Research, Rhode Island Hospital, Providence, RI, USA
| | - L Lecca
- Socios En Salud, Sucursal Perú, Lima, Peru
| | - M Franke
- Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA, USA
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12
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Brooks-Pollock E, Danon L, Korthals Altes H, Davidson JA, Pollock AMT, van Soolingen D, Campbell C, Lalor MK. A model of tuberculosis clustering in low incidence countries reveals more transmission in the United Kingdom than the Netherlands between 2010 and 2015. PLoS Comput Biol 2020; 16:e1007687. [PMID: 32218567 PMCID: PMC7141699 DOI: 10.1371/journal.pcbi.1007687] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 04/08/2020] [Accepted: 01/16/2020] [Indexed: 11/18/2022] Open
Abstract
Tuberculosis (TB) remains a public health threat in low TB incidence countries, through a combination of reactivated disease and onward transmission. Using surveillance data from the United Kingdom (UK) and the Netherlands (NL), we demonstrate a simple and predictable relationship between the probability of observing a cluster and its size (the number of cases with a single genotype). We demonstrate that the full range of observed cluster sizes can be described using a modified branching process model with the individual reproduction number following a Poisson lognormal distribution. We estimate that, on average, between 2010 and 2015, a TB case generated 0.41 (95% CrI 0.30,0.60) secondary cases in the UK, and 0.24 (0.14,0.48) secondary cases in the NL. A majority of cases did not generate any secondary cases. Recent transmission accounted for 39% (26%,60%) of UK cases and 23%(13%,37%) of NL cases. We predict that reducing UK transmission rates to those observed in the NL would result in 538(266,818) fewer cases annually in the UK. In conclusion, while TB in low incidence countries is strongly associated with reactivated infections, we demonstrate that recent transmission remains sufficient to warrant policies aimed at limiting local TB spread.
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Affiliation(s)
- Ellen Brooks-Pollock
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- Bristol Veterinary School, University of Bristol, Bristol, United Kingdom
- * E-mail:
| | - Leon Danon
- College of Engineering and Mathematical Sciences, University of Exeter, Exeter, United Kingdom
- The Alan Turing Institute, London, United Kingdom
| | - Hester Korthals Altes
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands
| | | | | | - Dick van Soolingen
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands
- Departments of Clinical Microbiology and Pulmonary Diseases, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
| | - Colin Campbell
- TB Section, Public Health England, London, United Kingdom
| | - Maeve K. Lalor
- TB Section, Public Health England, London, United Kingdom
- Institute for Global Health, University College London, London, United Kingdom
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13
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Abstract
Tuberculosis (TB) is the leading killer among all infectious diseases worldwide despite extensive use of the Mycobacterium bovis bacille Calmette-Guérin (BCG) vaccine. A safer and more effective vaccine than BCG is urgently required. More than a dozen TB vaccine candidates are under active evaluation in clinical trials aimed to prevent infection, disease, and recurrence. After decades of extensive research, renewed promise of an effective vaccine against this ancient airborne disease has recently emerged. In two innovative phase 2b vaccine clinical trials, one for the prevention of Mycobacterium tuberculosis infection in healthy adolescents and another for the prevention of TB disease in M. tuberculosis-infected adults, efficacy signals were observed. These breakthroughs, based on the greatly expanded knowledge of the M. tuberculosis infection spectrum, immunology of TB, and vaccine platforms, have reinvigorated the TB vaccine field. Here, we review our current understanding of natural immunity to TB, limitations in BCG immunity that are guiding vaccinologists to design novel TB vaccine candidates and concepts, and the desired attributes of a modern TB vaccine. We provide an overview of the progress of TB vaccine candidates in clinical evaluation, perspectives on the challenges faced by current vaccine concepts, and potential avenues to build on recent successes and accelerate the TB vaccine research-and-development trajectory.
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14
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Ackley SF, Lee RS, Worden L, Zwick E, Porco TC, Behr MA, Pepperell CS. Multiple exposures, reinfection and risk of progression to active tuberculosis. ROYAL SOCIETY OPEN SCIENCE 2019; 6:180999. [PMID: 31031990 PMCID: PMC6458392 DOI: 10.1098/rsos.180999] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 02/20/2019] [Indexed: 05/24/2023]
Abstract
A recent study reported on a tuberculosis (TB) outbreak in a largely Inuit village. Among newly infected individuals, exposure to additional active cases was associated with an increasing probability of developing active disease within a year. Using binomial risk models, we evaluated two potential mechanisms by which multiple infections during the first year following initial infection could account for increasing disease risk with increasing exposures. In the reinfection model, each infectious contact confers an independent risk of an infection, and infections contribute independently to active disease. In the threshold model, disease risk follows a sigmoidal function with small numbers of infectious contacts conferring a low risk of active disease and large numbers of contacts conferring a high risk. To determine the dynamic impact of reinfection during the early phase of infection, we performed simulations from a modified Reed-Frost model of TB dynamics following spread from an initial number of cases. We parametrized this model with the maximum-likelihood estimates from the reinfection and threshold models in addition to the observed distribution of exposures among new infections. We find that both models can plausibly account for the observed increase in disease risk with increasing infectious contacts, but the threshold model confers a better fit than a nested model without a threshold (p = 0.04). Our simulations indicate that multiple exposures to infectious individuals during this critical time period can lead to dramatic increases in outbreak size. In order to decrease TB burden in high-prevalence settings, it may be necessary to implement measures aimed at preventing repeated exposures, in addition to preventing primary infection.
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Affiliation(s)
- Sarah F. Ackley
- Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA
- Proctor Foundation, University of California, San Francisco, CA, USA
| | - Robyn S. Lee
- Department of Epidemiology, Harvard University, School of Public Health, Boston, MA, USA
| | - Lee Worden
- Proctor Foundation, University of California, San Francisco, CA, USA
| | - Erin Zwick
- Department of Population Health Sciences, University of Wisconsin – Madison, School of Medicine and Public Health, Madison, WI, USA
| | - Travis C. Porco
- Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA
- Proctor Foundation, University of California, San Francisco, CA, USA
- Department of Ophthalmology, University of California, San Francisco, CA, USA
| | - Marcel A. Behr
- Department of Medicine, McGill University, Montreal, Quebec, Canada
- McGill International TB Centre, Montreal, Quebec, Canada
| | - Caitlin S. Pepperell
- Medicine and Medical Microbiology and Immunology, University of Wisconsin – Madison, Madison, WI, USA
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15
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Wangari IM, Trauer J, Stone L. Modelling heterogeneity in host susceptibility to tuberculosis and its effect on public health interventions. PLoS One 2018; 13:e0206603. [PMID: 30427891 PMCID: PMC6235601 DOI: 10.1371/journal.pone.0206603] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 10/16/2018] [Indexed: 11/25/2022] Open
Abstract
A tuberculosis (TB) model that accounts for heterogeneity in host susceptibility to tuberculosis is proposed, with the aim of investigating the implications this may have for the effectiveness of public health interventions. The model examines the possibility that recovered individuals treated from active TB and individuals treated with preventive therapy acquire different levels of immunity. This contrasts with recent studies that assume the two cohorts acquire the same level of immunity, and therefore both groups are reinfected at the same rate. The analysis presented here examines the impact of this assumption when designing intervention strategies. Comparison of reinfection rates between cohorts treated with preventive therapy and recovered individuals who were previously treated for active TB provides important epidemiological insights. It is found that the reinfection rate of the cohort treated with preventive therapy is the one that plays the key role in qualitative changes in TB dynamics. By contrast, the reinfection rate of recovered individuals (previously treated from active TB) plays a minor role. Moreover, the study shows that preventive treatment of individuals during early latency is always beneficial regardless of the level of susceptibility to reinfection. Further, if patients have greater immunity following treatment for late latent infection, then treatment is again beneficial. However, if susceptibility increases following treatment for late latent infection, the effect of treatment depends on the epidemiological setting. That is: (i) in (very) low burden settings, the effect on reactivation predominates and the burden declines with treatment; (ii) in moderate to high burden settings the effect of reinfection predominates and burden increases with treatment. The effect is most dominant between the two reinfection thresholds, RT2 and RT1, respectively associated with individuals being treated with preventive therapy and individuals with untreated late latent TB infection.
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Affiliation(s)
- Isaac Mwangi Wangari
- Mathematical Sciences, School of Science, Royal Melbourne Institute of Technology, Melbourne, Victoria, Australia
- * E-mail:
| | - James Trauer
- School of Public Health and Preventive Medicine, Monash University, Melbourne 3004, Australia
| | - Lewi Stone
- Mathematical Sciences, School of Science, Royal Melbourne Institute of Technology, Melbourne, Victoria, Australia
- Biomathematics Unit, Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Israel
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16
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Quantifying TB transmission: a systematic review of reproduction number and serial interval estimates for tuberculosis. Epidemiol Infect 2018; 146:1478-1494. [PMID: 29970199 PMCID: PMC6092233 DOI: 10.1017/s0950268818001760] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tuberculosis (TB) is the leading global infectious cause of death. Understanding TB transmission is critical to creating policies and monitoring the disease with the end goal of TB elimination. To our knowledge, there has been no systematic review of key transmission parameters for TB. We carried out a systematic review of the published literature to identify studies estimating either of the two key TB transmission parameters: the serial interval (SI) and the reproductive number. We identified five publications that estimated the SI and 56 publications that estimated the reproductive number. The SI estimates from four studies were: 0.57, 1.42, 1.44 and 1.65 years; the fifth paper presented age-specific estimates ranging from 20 to 30 years (for infants <1 year old) to <5 years (for adults). The reproductive number estimates ranged from 0.24 in the Netherlands (during 1933-2007) to 4.3 in China in 2012. We found a limited number of publications and many high TB burden settings were not represented. Certain features of TB dynamics, such as slow transmission, complicated parameter estimation, require novel methods. Additional efforts to estimate these parameters for TB are needed so that we can monitor and evaluate interventions designed to achieve TB elimination.
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17
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Auld SC, Shah NS, Cohen T, Martinson NA, Gandhi NR. Where is tuberculosis transmission happening? Insights from the literature, new tools to study transmission and implications for the elimination of tuberculosis. Respirology 2018; 23:10.1111/resp.13333. [PMID: 29869818 PMCID: PMC6281783 DOI: 10.1111/resp.13333] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 05/14/2018] [Accepted: 05/20/2018] [Indexed: 12/12/2022]
Abstract
More than 10 million new cases of tuberculosis (TB) are diagnosed worldwide each year. The majority of these cases occur in low- and middle-income countries where the TB epidemic is predominantly driven by transmission. Efforts to 'end TB' will depend upon our ability to halt ongoing transmission. However, recent studies of new approaches to interrupt transmission have demonstrated inconsistent effects on reducing population-level TB incidence. TB transmission occurs across a wide range of settings, that include households and hospitals, but also community-based settings. While home-based contact investigations and infection control programmes in hospitals and clinics have a successful track record as TB control activities, there is a gap in our knowledge of where, and between whom, community-based transmission of TB occurs. Novel tools, including molecular epidemiology, geospatial analyses and ventilation studies, provide hope for improving our understanding of transmission in countries where the burden of TB is greatest. By integrating these diverse and innovative tools, we can enhance our ability to identify transmission events by documenting the opportunity for transmission-through either an epidemiologic or geospatial connection-alongside genomic evidence for transmission, based upon genetically similar TB strains. A greater understanding of locations and patterns of transmission will translate into meaningful improvements in our current TB control activities by informing targeted, evidence-based public health interventions.
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Affiliation(s)
- Sara C Auld
- Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
- Department of Epidemiology, Emory University Rollins School of Public Health, Atlanta, GA, USA
| | - N Sarita Shah
- Department of Epidemiology, Emory University Rollins School of Public Health, Atlanta, GA, USA
- Division of Global HIV and TB, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Ted Cohen
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Neil A Martinson
- Perinatal HIV Research Unit, University of the Witwatersrand, Johannesburg, South Africa
- Center for TB Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Neel R Gandhi
- Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA
- Department of Epidemiology, Emory University Rollins School of Public Health, Atlanta, GA, USA
- Department of Global Health, Emory University Rollins School of Public Health, Atlanta, GA, USA
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18
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Saunders MJ, Datta S. Contact Investigation: A Priority for Tuberculosis Control Programs. Am J Respir Crit Care Med 2017; 194:1049-1051. [PMID: 27797611 DOI: 10.1164/rccm.201605-1007ed] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Matthew J Saunders
- 1 Innovación Por la Salud y Desarrollo Asociación Benéfica PRISMA Lima, Perú.,2 Laboratory of Research and Development Universidad Peruana Cayetano Heredia Lima, Perú.,3 Section of Infectious Diseases and Immunity Imperial College London London, United Kingdom and.,4 Wellcome Trust Imperial College Centre for Global Health Research London, United Kingdom
| | - Sumona Datta
- 1 Innovación Por la Salud y Desarrollo Asociación Benéfica PRISMA Lima, Perú.,2 Laboratory of Research and Development Universidad Peruana Cayetano Heredia Lima, Perú.,3 Section of Infectious Diseases and Immunity Imperial College London London, United Kingdom and.,4 Wellcome Trust Imperial College Centre for Global Health Research London, United Kingdom
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19
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Mathema B, Andrews JR, Cohen T, Borgdorff MW, Behr M, Glynn JR, Rustomjee R, Silk BJ, Wood R. Drivers of Tuberculosis Transmission. J Infect Dis 2017; 216:S644-S653. [PMID: 29112745 PMCID: PMC5853844 DOI: 10.1093/infdis/jix354] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Measuring tuberculosis transmission is exceedingly difficult, given the remarkable variability in the timing of clinical disease after Mycobacterium tuberculosis infection; incident disease can result from either a recent (ie, weeks to months) or a remote (ie, several years to decades) infection event. Although we cannot identify with certainty the timing and location of tuberculosis transmission for individuals, approaches for estimating the individual probability of recent transmission and for estimating the fraction of tuberculosis cases due to recent transmission in populations have been developed. Data used to estimate the probable burden of recent transmission include tuberculosis case notifications in young children and trends in tuberculin skin test and interferon γ-release assays. More recently, M. tuberculosis whole-genome sequencing has been used to estimate population levels of recent transmission, identify the distribution of specific strains within communities, and decipher chains of transmission among culture-positive tuberculosis cases. The factors that drive the transmission of tuberculosis in communities depend on the burden of prevalent tuberculosis; the ways in which individuals live, work, and interact (eg, congregate settings); and the capacity of healthcare and public health systems to identify and effectively treat individuals with infectious forms of tuberculosis. Here we provide an overview of these factors, describe tools for measurement of ongoing transmission, and highlight knowledge gaps that must be addressed.
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Affiliation(s)
- Barun Mathema
- Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York
| | - Jason R Andrews
- Division of Infectious Diseases and Geographic Medicine, Stanford University, California
| | - Ted Cohen
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut
| | - Martien W Borgdorff
- Centers for Disease Control and Prevention, Kisumu, Kenya
- Department of Clinical Epidemiology, Biostatistics, and Bioinformatics, Academic Medical Center, University of Amsterdam, the Netherlands
| | - Marcel Behr
- McGill International TB Centre, Research Institute of the McGill University Health Centre, Montreal,Canada
| | - Judith R Glynn
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Roxana Rustomjee
- Tuberculosis Clinical Research Branch, Therapeutics Research Program, Division of AIDS, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland
| | - Benjamin J Silk
- Division of Tuberculosis Elimination, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Robin Wood
- Desmond Tutu HIV Centre, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, South Africa
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20
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Abstract
BACKGROUND Tuberculosis (TB) contact investigation has been observed as a useful programmatic tool in active case finding. We collected data of contact cases to evaluate the effectiveness of TB contact investigation programme in Shanghai, China. METHODS Since 2009, we screened and followed up the close contacts of bacteria-positive TB cases in Songjiang, Shanghai and calculated the incidence of TB in close contacts and confirmed the transmission by genotyping and sequencing. RESULTS A total of 4584 close contacts of 1765 contagious TB index cases were followed up for an average of 4 years. About 62 contacts (333/100 000, 95% CI: 256-428) developed TB excluding 6 co-prevalent cases. The contact cases consisted 1.50% (39/2592) of all the bacteria-positive cases in population. Transmission links were confirmed in 60% (9/15) familial contacts and 22% (2/9) in non-familial contacts. Source cases come from more than close contacts and both index and contact cases created other secondary cases in community. CONCLUSIONS Familial contacts are more likely to acquire TB from the index, indicating the priority of family members in TB contact investigation in China. However, most non-familial contacts were infected from sources in the community and contact cases attributed little to case finding in the TB-prevalent setting. Thus, active case finding should be strengthened in general population.
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21
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Datta S, Sherman JM, Tovar MA, Bravard MA, Valencia T, Montoya R, Quino W, D'Arcy N, Ramos ES, Gilman RH, Evans CA. Sputum Microscopy With Fluorescein Diacetate Predicts Tuberculosis Infectiousness. J Infect Dis 2017; 216:514-524. [PMID: 28510693 PMCID: PMC5853787 DOI: 10.1093/infdis/jix229] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 05/11/2017] [Indexed: 01/03/2023] Open
Abstract
Background Sputum from patients with tuberculosis contains subpopulations of metabolically active and inactive Mycobacterium tuberculosis with unknown implications for infectiousness. Methods We assessed sputum microscopy with fluorescein diacetate (FDA, evaluating M. tuberculosis metabolic activity) for predicting infectiousness. Mycobacterium tuberculosis was quantified in pretreatment sputum of patients with pulmonary tuberculosis using FDA microscopy, culture, and acid-fast microscopy. These 35 patients’ 209 household contacts were followed with prevalence surveys for tuberculosis disease for 6 years. Results FDA microscopy was positive for a median of 119 (interquartile range [IQR], 47–386) bacteria/µL sputum, which was 5.1% (IQR, 2.4%–11%) the concentration of acid-fast microscopy–positive bacteria (2069 [IQR, 1358–3734] bacteria/μL). Tuberculosis was diagnosed during follow-up in 6.4% (13/209) of contacts. For patients with lower than median concentration of FDA microscopy–positive M. tuberculosis, 10% of their contacts developed tuberculosis. This was significantly more than 2.7% of the contacts of patients with higher than median FDA microscopy results (crude hazard ratio [HR], 3.8; P = .03). This association maintained statistical significance after adjusting for disease severity, chemoprophylaxis, drug resistance, and social determinants (adjusted HR, 3.9; P = .02). Conclusions Mycobacterium tuberculosis that was FDA microscopy negative was paradoxically associated with greater infectiousness. FDA microscopy–negative bacteria in these pretreatment samples may be a nonstaining, slowly metabolizing phenotype better adapted to airborne transmission.
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Affiliation(s)
- Sumona Datta
- Innovation for Health and Development (IFHAD), Laboratory of Research and Development, Universidad Peruana Cayetano Heredia, Lima, Peru.,Infectious Diseases and Immunity and Wellcome Trust Centre for Global Health Research, Imperial College London, United Kingdom.,Innovacion por la Salud y el Desarollo (IPSYD), Asociación Benéfica Prisma, Lima, Peru
| | - Jonathan M Sherman
- Innovation for Health and Development (IFHAD), Laboratory of Research and Development, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Marco A Tovar
- Innovation for Health and Development (IFHAD), Laboratory of Research and Development, Universidad Peruana Cayetano Heredia, Lima, Peru.,Innovacion por la Salud y el Desarollo (IPSYD), Asociación Benéfica Prisma, Lima, Peru
| | - Marjory A Bravard
- Innovation for Health and Development (IFHAD), Laboratory of Research and Development, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Teresa Valencia
- Innovation for Health and Development (IFHAD), Laboratory of Research and Development, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Rosario Montoya
- Innovacion por la Salud y el Desarollo (IPSYD), Asociación Benéfica Prisma, Lima, Peru
| | - Willi Quino
- Innovation for Health and Development (IFHAD), Laboratory of Research and Development, Universidad Peruana Cayetano Heredia, Lima, Peru.,Innovacion por la Salud y el Desarollo (IPSYD), Asociación Benéfica Prisma, Lima, Peru
| | - Nikki D'Arcy
- Innovation for Health and Development (IFHAD), Laboratory of Research and Development, Universidad Peruana Cayetano Heredia, Lima, Peru.,Innovacion por la Salud y el Desarollo (IPSYD), Asociación Benéfica Prisma, Lima, Peru
| | - Eric S Ramos
- Innovation for Health and Development (IFHAD), Laboratory of Research and Development, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Robert H Gilman
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Carlton A Evans
- Innovation for Health and Development (IFHAD), Laboratory of Research and Development, Universidad Peruana Cayetano Heredia, Lima, Peru.,Infectious Diseases and Immunity and Wellcome Trust Centre for Global Health Research, Imperial College London, United Kingdom.,Innovacion por la Salud y el Desarollo (IPSYD), Asociación Benéfica Prisma, Lima, Peru
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22
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Jones-López EC, Acuña-Villaorduña C, Fregona G, Marques-Rodrigues P, White LF, Hadad DJ, Dutra-Molina LP, Vinhas S, McIntosh AI, Gaeddert M, Ribeiro-Rodrigues R, Salgame P, Palaci M, Alland D, Ellner JJ, Dietze R. Incident Mycobacterium tuberculosis infection in household contacts of infectious tuberculosis patients in Brazil. BMC Infect Dis 2017; 17:576. [PMID: 28821234 PMCID: PMC5563014 DOI: 10.1186/s12879-017-2675-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 08/08/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In household contact investigations of tuberculosis (TB), a second tuberculin skin test (TST) obtained several weeks after a first negative result consistently identifies individuals that undergo TST conversion. It remains unclear whether this delay in M. tuberculosis infection is related to differences in the infectious exposure, TST boosting, partial host resistance, or some other factor. METHODS We conducted a household contact study Vitória, Brazil. Between 2008 and 2013, we identified culture-positive pulmonary TB patients and evaluated their household contacts with both a TST and interferon gamma release assay (IGRA), and identified TST converters at 8-12 weeks post study enrollment. Contacts were classified as TST-positive (≥10 mm) at baseline, TST converters, or persistently TST-negative. We compared TST converters to TST-positive and to TST-negative contacts separately, using generalized estimating equations. RESULTS We enrolled 160 index patients and 838 contacts; 523 (62.4%) were TST+, 62 (7.4%) TST converters, and 253 (30.2%) TST-. TST converters were frequently IGRA- at 8-12 weeks. In adjusted analyses, characteristics distinguishing TST converters from TST+ contacts (no contact with another TB patient and residence ownership) were different than those differentiating them from TST- contacts (stronger cough in index patient and contact BCG scar). CONCLUSIONS The individual risk and timing of M. tuberculosis infection within households is variable and dependent on index patient, contact and environmental factors within the household, and the surrounding community. Our findings suggest a threshold effect in the risk of infection in humans.
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Affiliation(s)
- Edward C Jones-López
- Section of Infectious Diseases, Department of Medicine, Boston Medical Center and Boston University School of Medicine, 650 Albany Street, Room 605, Boston, MA, 02118, USA.
| | - Carlos Acuña-Villaorduña
- Section of Infectious Diseases, Department of Medicine, Boston Medical Center and Boston University School of Medicine, 650 Albany Street, Room 605, Boston, MA, 02118, USA.
| | - Geisa Fregona
- Núcleo de Doenças Infecciosas, Universidade Federal do Espírito Santo (UFES), Vitória, Brazil
| | | | - Laura F White
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - David Jamil Hadad
- Núcleo de Doenças Infecciosas, Universidade Federal do Espírito Santo (UFES), Vitória, Brazil
| | | | - Solange Vinhas
- Mycobacteriology Laboratory, Núcleo de Doenças Infecciosas, UFES, Vitória, Brazil
| | - Avery I McIntosh
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - Mary Gaeddert
- Section of Infectious Diseases, Department of Medicine, Boston Medical Center and Boston University School of Medicine, 650 Albany Street, Room 605, Boston, MA, 02118, USA
| | | | - Padmini Salgame
- Division of Infectious Diseases, Department of Medicine, New Jersey Medical School- Rutgers University, Newark, NJ, USA
| | - Moises Palaci
- Mycobacteriology Laboratory, Núcleo de Doenças Infecciosas, UFES, Vitória, Brazil
| | - David Alland
- Division of Infectious Diseases, Department of Medicine, New Jersey Medical School- Rutgers University, Newark, NJ, USA
| | - Jerrold J Ellner
- Section of Infectious Diseases, Department of Medicine, Boston Medical Center and Boston University School of Medicine, 650 Albany Street, Room 605, Boston, MA, 02118, USA
| | - Reynaldo Dietze
- Núcleo de Doenças Infecciosas, Universidade Federal do Espírito Santo (UFES), Vitória, Brazil
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Lalor MK, Anderson LF, Hamblion EL, Burkitt A, Davidson JA, Maguire H, Abubakar I, Thomas HL. Recent household transmission of tuberculosis in England, 2010-2012: retrospective national cohort study combining epidemiological and molecular strain typing data. BMC Med 2017; 15:105. [PMID: 28606177 PMCID: PMC5469076 DOI: 10.1186/s12916-017-0864-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 04/27/2017] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND We estimate the proportion of tuberculosis (TB) in England due to recent household transmission, identify factors associated with being a household transmitter, and investigate the impact that identification of a case has on time to treatment of subsequent cases. METHODS TB cases notified between 2010 and 2012 in England in the same household as another case were identified; 24 locus MIRU-VNTR strain typing (ST) was used to identify household cases with likely recent transmission. Treatment delay in index and subsequent cases was compared. Risk factors for being a household transmitter were identified in univariable and multivariable analyses. RESULTS Overall, 7.7% (1849/24,060) of TB cases lived in a household with another case. We estimate that 3.9% were due to recent household transmission. ST data was unavailable for 67% (1242) of household pairs. For those with ST data, 64% (386) had confirmed, 11% probable (66) and 25% (155) refuted household transmission. The median treatment delay was 65 days for index cases and 37 days for subsequent asymptomatic cases. Risk factors for being a household transmitter included being under 25 years old, UK-born with Black African, Indian or Pakistani ethnicity, or born in Somalia or Romania. CONCLUSIONS This study has a number of implications for household TB contact tracing in low incidence countries, including the potential to reduce the diagnostic delay for subsequent household cases and the benefit of using ST to identify when to conduct source contact tracing outside the household. As 25% of TB cases in households had discordant strains, households with multiple TB cases do not necessarily represent household transmission. The additional fact that 25% of index cases within households only had extra-pulmonary TB demonstrates that, if household contact tracing is limited to pulmonary TB cases (as recently recommended in UK guidelines), additional cases of active TB in households will be missed. Our finding that no lineage of TB was associated with recent household transmission and with no increased transmissibility in the Beijing lineage compared to others, suggests that the lineage need not impact contact tracing efforts. Improvements in contact tracing have the potential to reduce transmission of TB in low incidence countries.
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Affiliation(s)
- Maeve K Lalor
- TB Section, Centre for Infectious Disease Surveillance, National Infection Service, Public Health England, London, UK. .,Institute for Global Health, University College London, London, UK.
| | - Laura F Anderson
- TB Section, Centre for Infectious Disease Surveillance, National Infection Service, Public Health England, London, UK
| | - Esther L Hamblion
- Field Epidemiology Services, National Infection Service, Public Health England, London, UK
| | - Andy Burkitt
- Field Epidemiology Services, National Infection Service, Public Health England, London, UK.,Field Epidemiology Services, National Infection Service, Public Health England, Newcastle upon Tyne, UK
| | - Jennifer A Davidson
- TB Section, Centre for Infectious Disease Surveillance, National Infection Service, Public Health England, London, UK
| | - Helen Maguire
- Institute for Global Health, University College London, London, UK.,Field Epidemiology Services, National Infection Service, Public Health England, London, UK
| | - Ibrahim Abubakar
- TB Section, Centre for Infectious Disease Surveillance, National Infection Service, Public Health England, London, UK.,Institute for Global Health, University College London, London, UK
| | - H Lucy Thomas
- TB Section, Centre for Infectious Disease Surveillance, National Infection Service, Public Health England, London, UK
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24
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Patterson B, Morrow CD, Kohls D, Deignan C, Ginsburg S, Wood R. Mapping sites of high TB transmission risk: Integrating the shared air and social behaviour of TB cases and adolescents in a South African township. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 583:97-103. [PMID: 28109661 PMCID: PMC5312671 DOI: 10.1016/j.scitotenv.2017.01.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 12/20/2016] [Accepted: 01/04/2017] [Indexed: 05/08/2023]
Abstract
BACKGROUND Tuberculosis remains a major public health problem in poverty-stricken areas of the world. Communal gathering places account for the majority of TB transmission in high burden settings. OBJECTIVE To investigate the social behaviour patterns of individuals who have developed TB disease and adolescents at risk of infection. To develop a cheap and effective method to locate transmission hot spots in high burden communities. DESIGN Portable, combined CO2/GIS monitors and location diaries were given to individuals from a South African township. The three groups: newly diagnosed TB patients, recently treated TB patients and adolescents recorded their activities over a median of two days. Rebreathed air volumes (RAVs) at all GIS locations were calculated from CO2 levels using the Rudnick-Milton variant of the Wells-Riley TB transmission model. Hot spot analysis was performed to determine the communal buildings which correspond to spatially clustered high RAVs. RESULTS Analysis of diaries found that the adolescent group spent greater time in congregate settings compared with the other two groups driven by time spent in school/work (new TB: 1%, recent TB: 8%, and adolescents: 23%). Adolescents also changed their location more frequently (9.0, 6.0, 14.3 changes per day; p<0.001). The RAVs reflected this divergence between the groups (44, 40, 127l; p<0.001). Communal buildings associated with high RAVs were found to be a clinic, two schools and a library. Hot spot analysis revealed the most intense clustering of high RAVs at a community school. CONCLUSION Our study demonstrates a new methodology to uncover TB transmission hot spots using a technique that avoids the need to pre-select locations. Investigation of a South African township highlighted the high risk potential of schools and high risk social behaviour of adolescents. Consequently the targeting of transmission reduction strategies to schools may prove highly efficacious in high burden settings.
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Affiliation(s)
- Benjamin Patterson
- Division of Infectious Diseases, Columbia University, College of Physicians and Surgeons, New York, NY, USA; Desmond Tutu HIV Centre, IDM, University of Cape Town, Cape Town, South Africa.
| | - Carl D Morrow
- Institute of Infectious Disease and Molecular Medicine (IDM), Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa; Desmond Tutu HIV Centre, IDM, University of Cape Town, Cape Town, South Africa
| | - Daniel Kohls
- Desmond Tutu HIV Centre, IDM, University of Cape Town, Cape Town, South Africa
| | - Caroline Deignan
- Desmond Tutu HIV Centre, IDM, University of Cape Town, Cape Town, South Africa
| | - Samuel Ginsburg
- Department of Electrical Engineering, Faculty of Engineering & the Built Environment, University of Cape Town, South Africa
| | - Robin Wood
- Institute of Infectious Disease and Molecular Medicine (IDM), Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa; Desmond Tutu HIV Centre, IDM, University of Cape Town, Cape Town, South Africa
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25
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McIntosh AI, Doros G, Jones-López EC, Gaeddert M, Jenkins HE, Marques-Rodrigues P, Ellner JJ, Dietze R, White LF. Extensions to Bayesian generalized linear mixed effects models for household tuberculosis transmission. Stat Med 2017; 36:2522-2532. [PMID: 28370491 DOI: 10.1002/sim.7303] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 03/15/2017] [Indexed: 02/01/2023]
Abstract
Household contact studies, a mainstay of tuberculosis transmission research, often assume that tuberculosis-infected household contacts of an index case were infected within the household. However, strain genotyping has provided evidence against this assumption. Understanding the household versus community infection dynamic is essential for designing interventions. The misattribution of infection sources can also bias household transmission predictor estimates. We present a household-community transmission model that estimates the probability of community infection, that is, the probability that a household contact of an index case was actually infected from a source outside the home and simultaneously estimates transmission predictors. We show through simulation that our method accurately predicts the probability of community infection in several scenarios and that not accounting for community-acquired infection in household contact studies can bias risk factor estimates. Applying the model to data from Vitória, Brazil, produced household risk factor estimates similar to two other standard methods for age and sex. However, our model gave different estimates for sleeping proximity to index case and disease severity score. These results show that estimating both the probability of community infection and household transmission predictors is feasible and that standard tuberculosis transmission models likely underestimate the risk for two important transmission predictors. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Avery I McIntosh
- Department of Biostatistics, Boston University, Boston, Massachusetts, U.S.A.,Section of Infectious Diseases, Department of Medicine, Boston Medical Center, School of Medicine, Boston University, Boston, Massachusetts, U.S.A
| | - Gheorghe Doros
- Department of Biostatistics, Boston University, Boston, Massachusetts, U.S.A
| | - Edward C Jones-López
- Section of Infectious Diseases, Department of Medicine, Boston Medical Center, School of Medicine, Boston University, Boston, Massachusetts, U.S.A
| | - Mary Gaeddert
- Section of Infectious Diseases, Department of Medicine, Boston Medical Center, School of Medicine, Boston University, Boston, Massachusetts, U.S.A
| | - Helen E Jenkins
- Department of Biostatistics, Boston University, Boston, Massachusetts, U.S.A
| | | | - Jerrold J Ellner
- Section of Infectious Diseases, Department of Medicine, Boston Medical Center, School of Medicine, Boston University, Boston, Massachusetts, U.S.A
| | - Reynaldo Dietze
- Núcleo de Doenças Infecciosas, Universidade Federal do Espírito Santo (UFES), Vitória, Brazil
| | - Laura F White
- Department of Biostatistics, Boston University, Boston, Massachusetts, U.S.A
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26
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Tiemersma EW, Huong NT, Yen PH, Tinh BT, Thuy TTB, Van Hung N, Mai NT, Verver S, Gebhard A, Nhung NV. Infection control and tuberculosis among health care workers in Viet Nam, 2009-2013: a cross-sectional survey. BMC Infect Dis 2016; 16:664. [PMID: 27832744 PMCID: PMC5103393 DOI: 10.1186/s12879-016-1993-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 10/29/2016] [Indexed: 11/10/2022] Open
Abstract
Background Data on tuberculosis (TB) among health care workers (HCW) and TB infection control (TBIC) indicators are rarely available at national level. We assessed multi-year trends in notification data of TB among HCW and explored possible associations with TBIC indicators. Methods Notified TB incidence among HCW and 3 other TBIC indicators were collected annually from all 64 provincial and 3 national TB facilities in Vietnam. Time trends in TB notification between 2009 and 2013 were assessed using linear regression analysis. Multivariate regression models were applied to assess associations between the facility-specific 5-year notification rate and TBIC indicators. Results Forty-seven (70 %) of 67 facilities contributed data annually over five years; 15 reported at least one HCW with TB in 2009 compared to six in 2013. The TB notification rate dropped from 593 to 197 per 100,000 HCW (ptrend = 0.02). Among 104 TB cases reported, 30 were employed at TB wards, 24 at other clinical wards, ten in the microbiology laboratory, six at the MDR-TB ward, and 34 in other positions. The proportion of facilities with a TBIC plan and focal person remained relatively stable between 70 % and 84 %. The proportion of facilities providing personal protective equipment (PPE) to their staff increased over time. Facilities with a TBIC focal person were 7.6 times more likely to report any TB cases than facilities without a focal person. Conclusions The TB notification rates among HCW seemed to decrease over time. Availability of PPE increased over the same period. Appointing a TBIC focal person was associated with reporting of TB cases among HCW. It remains unclear whether TBIC measures helped in reduction of the TB notification rates in HCW.
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Affiliation(s)
- Edine W Tiemersma
- KNCV Tuberculosis Foundation, Benoordenhoutseweg 46, 2596 BC, The Hague, The Netherlands.
| | - Nguyen Thien Huong
- KNCV Tuberculosis Foundation Vietnam Country Office, 130 Mai Anh Tuan Street, Hanoi, Vietnam
| | - Pham Hoang Yen
- National Tuberculosis Control Program of Vietnam, 463 Hoang Hoa Tham, Hanoi, Vietnam
| | - Bui Thi Tinh
- KNCV Tuberculosis Foundation Vietnam Country Office, 130 Mai Anh Tuan Street, Hanoi, Vietnam
| | - Tran Thi Bich Thuy
- National Tuberculosis Control Program of Vietnam, 463 Hoang Hoa Tham, Hanoi, Vietnam
| | - Nguyen Van Hung
- National Tuberculosis Control Program of Vietnam, 463 Hoang Hoa Tham, Hanoi, Vietnam
| | - Nguyen Thanh Mai
- Pham Ngoc Thach Hospital, 120 Hong Bang, Ho Chi Minh City, Vietnam
| | - Suzanne Verver
- KNCV Tuberculosis Foundation, Benoordenhoutseweg 46, 2596 BC, The Hague, The Netherlands
| | - Agnes Gebhard
- KNCV Tuberculosis Foundation, Benoordenhoutseweg 46, 2596 BC, The Hague, The Netherlands
| | - Nguyen Viet Nhung
- National Tuberculosis Control Program of Vietnam, 463 Hoang Hoa Tham, Hanoi, Vietnam
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27
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Lee SH. Tuberculosis Infection and Latent Tuberculosis. Tuberc Respir Dis (Seoul) 2016; 79:201-206. [PMID: 27790271 PMCID: PMC5077723 DOI: 10.4046/trd.2016.79.4.201] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 02/18/2016] [Accepted: 03/09/2016] [Indexed: 11/24/2022] Open
Abstract
Active tuberculosis (TB) has a greater burden of TB bacilli than latent TB and acts as an infection source for contacts. Latent tuberculosis infection (LTBI) is the state in which humans are infected with Mycobacterium tuberculosis without any clinical symptoms, radiological abnormality, or microbiological evidence. TB is transmissible by respiratory droplet nucleus of 1–5 µm in diameter, containing 1–10 TB bacilli. TB transmission is affected by the strength of the infectious source, infectiousness of TB bacilli, immunoresistance of the host, environmental stresses, and biosocial factors. Infection controls to reduce TB transmission consist of managerial activities, administrative control, engineering control, environmental control, and personal protective equipment provision. However, diagnosis and treatment for LTBI as a national TB control program is an important strategy on the precondition that active TB is not missed. Therefore, more concrete evidences for LTBI management based on clinical and public perspectives are needed.
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Affiliation(s)
- Seung Heon Lee
- Division of Pulmonary, Sleep, and Critical Care Medicine, Department of Internal Medicine, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, Korea
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28
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Evaluation of exposure of pemphigus vulgaris patients to Mycobacterium tuberculosis and Aspergillus fumigatus. Eur J Clin Microbiol Infect Dis 2016; 35:1749-1752. [PMID: 27396270 DOI: 10.1007/s10096-016-2721-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 06/29/2016] [Indexed: 10/21/2022]
Abstract
The purpose of this study was to screen pemphigus vulgaris (PV) (autoimmune bullous skin disease) for the presence of immunoglobulin G against Mycobacterium tuberculosis and Aspergillus fumigatus. The sera of 60 PV patients and 28 controls were screened for the presence of immunoglobulin G against M. tuberculosis and A. fumigatus by enzyme-linked immune-sorbent assay. Forty patients were females and 20 were males. The range of IgG against M. tuberculosis was from 0.9 to 152.6 (median = 2.95) in the patients and was from 0 to 2.2 (median = 1.6) in the controls. Seven (11.7 %) patients and none of the controls exceeded the cut-off value. Four patients were on systemic steroids and azathioprine and three did not receive treatment before. The results showed that PV patients had significantly more IgG against M. tuberculosis than the controls; the p value was 0.006. The range of IgG against A. fumigatus was from 1.3 to 76.3 (median = 4.9) in the patients and was from 1 to 105.3 (median = 5.25) in the controls. Six (10 %) patients and eight (28.6 %) controls exceeded the cut-off value. The six patients were on systemic steroids and azathioprine. No significant difference was detected between PV patients and controls regarding exposure to A. fumigatus; the p value was 0.308. PV patients showed significantly more exposure to the M. tuberculosis than the controls. This suggests that M. tuberculosis may contribute to the pathogenesis of PV.
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29
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Otero L, Shah L, Verdonck K, Battaglioli T, Brewer T, Gotuzzo E, Seas C, Van der Stuyft P. A prospective longitudinal study of tuberculosis among household contacts of smear-positive tuberculosis cases in Lima, Peru. BMC Infect Dis 2016; 16:259. [PMID: 27278655 PMCID: PMC4898451 DOI: 10.1186/s12879-016-1616-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 06/03/2016] [Indexed: 11/24/2022] Open
Abstract
Background Household contacts (HHCs) of TB cases are at increased risk for TB disease compared to the general population but the risk may be modified by individual or household factors. We conducted a study to determine incident TB among HHCs over two years after exposure and to identify individual and household level risk factors. Methods Adults newly diagnosed with a first episode of smear-positive pulmonary TB (index cases) between March 2010 and December 2011 in eastern Lima, were interviewed to identify their HHC and household characteristics. TB registers were reviewed for up to two years after the index case diagnosis and house visits were made to ascertain TB cases among HHC. The TB incidence rate ratio among HHCs as a function of risk factors was determined using generalized linear mixed models. Results The 1178 index cases reported 5466 HHCs. In 402/1178 (34.1 %) households, at least one HHC had experienced a TB episode ever. The TB incidence among HHCs was 1918 (95%CI 1669–2194) per 100,000 person-years overall, and was 2392 (95%CI 2005–2833) and 1435 (95%CI 1139–1787) per 100,000 person-years in the first and second year, respectively. Incident TB occurred more than six months following the index case’s TB diagnosis in 121/205 (59.0 %) HHCs. In HHCs, bacillary load and time between symptoms and treatment initiation in the index case, as well as the relationship to the index case and the sex of the HHC all had a significant association with TB incidence in HHCs. Conclusions Incidence of TB among HHCs was more than ten times higher than in the general population. Certain HHC and households were at higher risk of TB, we recommend studies to compare HHC investigation to households at highest risk versus current practice, in terms of efficiency. Electronic supplementary material The online version of this article (doi:10.1186/s12879-016-1616-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Larissa Otero
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martín de Porres, Lima 31, Peru. .,Department of Public Health, Unit of General Epidemiology and Disease Control, Institute of Tropical Medicine, Antwerp, Belgium.
| | - Lena Shah
- Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Canada
| | - Kristien Verdonck
- Department of Public Health, Unit of Epidemiology and Control of Tropical Diseases, Institute of Tropical Medicine, Antwerp, Belgium
| | - Tullia Battaglioli
- Department of Public Health, Unit of General Epidemiology and Disease Control, Institute of Tropical Medicine, Antwerp, Belgium
| | - Timothy Brewer
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Eduardo Gotuzzo
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martín de Porres, Lima 31, Peru
| | - Carlos Seas
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martín de Porres, Lima 31, Peru
| | - Patrick Van der Stuyft
- Department of Public Health, Unit of General Epidemiology and Disease Control, Institute of Tropical Medicine, Antwerp, Belgium.,Department of Public Health, Ghent University, Ghent, Belgium
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30
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Yates TA, Khan PY, Knight GM, Taylor JG, McHugh TD, Lipman M, White RG, Cohen T, Cobelens FG, Wood R, Moore DAJ, Abubakar I. The transmission of Mycobacterium tuberculosis in high burden settings. THE LANCET. INFECTIOUS DISEASES 2016; 16:227-38. [PMID: 26867464 DOI: 10.1016/s1473-3099(15)00499-5] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 11/03/2015] [Accepted: 11/26/2015] [Indexed: 01/06/2023]
Abstract
Unacceptable levels of Mycobacterium tuberculosis transmission are noted in high burden settings and a renewed focus on reducing person-to-person transmission in these communities is needed. We review recent developments in the understanding of airborne transmission. We outline approaches to measure transmission in populations and trials and describe the Wells-Riley equation, which is used to estimate transmission risk in indoor spaces. Present research priorities include the identification of effective strategies for tuberculosis infection control, improved understanding of where transmission occurs and the transmissibility of drug-resistant strains, and estimates of the effect of HIV and antiretroviral therapy on transmission dynamics. When research is planned and interventions are designed to interrupt transmission, resource constraints that are common in high burden settings-including shortages of health-care workers-must be considered.
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Affiliation(s)
- Tom A Yates
- Centre for Infectious Disease Epidemiology, Research Department of Infection and Population Health, University College London, London, UK; Wellcome Trust Africa Centre for Population Health, Mtubatuba, South Africa, London School of Hygiene & Tropical Medicine, London, UK.
| | - Palwasha Y Khan
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK; Tuberculosis Centre, London School of Hygiene & Tropical Medicine, London, UK; Karonga Prevention Study, Chilumba, Malawi
| | - Gwenan M Knight
- Tuberculosis Centre, London School of Hygiene & Tropical Medicine, London, UK; Tuberculosis Modelling Group, London School of Hygiene & Tropical Medicine, London, UK; National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infection and Antimicrobial Resistance, Imperial College London, London, UK
| | - Jonathon G Taylor
- UCL Institute for Environmental Design and Engineering, Bartlett School of Environment, Energy and Resources, University College London, London, UK
| | - Timothy D McHugh
- Centre for Clinical Microbiology, University College London, London, UK
| | - Marc Lipman
- Division of Medicine, University College London, London, UK
| | - Richard G White
- Tuberculosis Centre, London School of Hygiene & Tropical Medicine, London, UK; Tuberculosis Modelling Group, London School of Hygiene & Tropical Medicine, London, UK
| | - Ted Cohen
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Frank G Cobelens
- Department of Global Health, Academic Medical Center, Amsterdam, Netherlands; KNCV Tuberculosis Foundation, The Hague, Netherlands
| | - Robin Wood
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK; Tuberculosis Centre, London School of Hygiene & Tropical Medicine, London, UK; The Desmond Tutu HIV Centre, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - David A J Moore
- Tuberculosis Centre, London School of Hygiene & Tropical Medicine, London, UK; Department of Clinical Research, London School of Hygiene & Tropical Medicine, London, UK
| | - Ibrahim Abubakar
- Centre for Infectious Disease Epidemiology, Research Department of Infection and Population Health, University College London, London, UK; MRC Clinical Trials Unit at University College London, University College London, London, UK
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Abstract
SUMMARY Tuberculosis (TB) is a leading cause of death worldwide despite the availability of effective chemotherapy for over 60 years. Although Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccination protects against active TB disease in some populations, its efficacy is suboptimal. Development of an effective TB vaccine is a top global priority that has been hampered by an incomplete understanding of protective immunity to TB. Thus far, preventing TB disease, rather than infection, has been the primary target for vaccine development. Several areas of research highlight the importance of including preinfection vaccines in the development pipeline. First, epidemiology and mathematical modeling studies indicate that a preinfection vaccine would have a high population-level impact for control of TB disease. Second, immunology studies support the rationale for targeting prevention of infection, with evidence that host responses may be more effective during acute infection than during chronic infection. Third, natural history studies indicate that resistance to TB infection occurs in a small percentage of the population. Fourth, case-control studies of BCG indicate that it may provide protection from infection. Fifth, prevention-of-infection trials would have smaller sample sizes and a shorter duration than disease prevention trials and would enable opportunities to search for correlates of immunity as well as serve as a criterion for selecting a vaccine product for testing in a larger TB disease prevention trial. Together, these points support expanding the focus of TB vaccine development efforts to include prevention of infection as a primary goal along with vaccines or other interventions that reduce the rate of transmission and reactivation.
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32
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Salgame P, Geadas C, Collins L, Jones-López E, Ellner JJ. Latent tuberculosis infection--Revisiting and revising concepts. Tuberculosis (Edinb) 2015; 95:373-84. [PMID: 26038289 DOI: 10.1016/j.tube.2015.04.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 04/09/2015] [Indexed: 12/14/2022]
Abstract
Host- and pathogen-specific factors interplay with the environment in a complex fashion to determine the outcome of infection with Mycobacterium tuberculosis (Mtb), resulting in one of three possible outcomes: cure, latency or active disease. Although much remains unknown about its pathophysiology, latent tuberculosis infection (LTBI) defined by immunologic evidence of Mtb infection is a continuum between self-cure and asymptomatic, yet active tuberculosis (TB) disease. Strain virulence, intensity of exposure to the index case, size of the bacterial inoculum, and host factors such as age and co-morbidities, each contribute to where one settles on the continuum. Currently, the diagnosis of LTBI is based on reactive tuberculin skin testing (TST) and/or a positive interferon-gamma release assay (IGRA). Neither diagnostic test reflects the activity of the infectious focus or the risk of progression to active TB. This is a critical shortcoming, as accurate and efficient detection of those with LTBI at higher risk of progression to TB disease would allow for provision of targeted preventive therapy to those most likely to benefit. Host biomarkers may prove of value in stratifying risk of development of TB. New guidelines are required for interpretation of discordance between TST and IGRA, which may be due in part to a lack of stability (that is reproducibility) of IGRA or TST results or to a delay in conversion of IGRA to positivity compared to TST. In this review, the authors elaborate on the definition, diagnosis, pathophysiology and natural history of LTBI, as well as promising methods for better stratifying risk of progression to TB. The review is centered on the human host and the clinical and epidemiologic features of LTBI that are relevant to the development of new and improved diagnostic tools.
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Affiliation(s)
- Padmini Salgame
- Division of Infectious Diseases, Department of Medicine, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Carolina Geadas
- Section of Infectious Diseases, Department of Medicine, Boston Medical Center and Boston University School of Medicine, Boston, MA, USA
| | - Lauren Collins
- Department of Internal Medicine, Duke University Medical Center, Durham, NC, USA
| | - Edward Jones-López
- Section of Infectious Diseases, Department of Medicine, Boston Medical Center and Boston University School of Medicine, Boston, MA, USA
| | - Jerrold J Ellner
- Section of Infectious Diseases, Department of Medicine, Boston Medical Center and Boston University School of Medicine, Boston, MA, USA.
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33
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Wood R, Morrow C, Ginsberg S, Piccoli E, Kalil D, Sassi A, Walensky RP, Andrews JR. Quantification of shared air: a social and environmental determinant of airborne disease transmission. PLoS One 2014; 9:e106622. [PMID: 25181526 PMCID: PMC4152288 DOI: 10.1371/journal.pone.0106622] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 07/30/2014] [Indexed: 12/03/2022] Open
Abstract
Background Tuberculosis is endemic in Cape Town, South Africa where a majority of the population become tuberculosis infected before adulthood. While social contact patterns impacting tuberculosis and other respiratory disease spread have been studied, the environmental determinants driving airborne transmission have not been quantified. Methods Indoor carbon dioxide levels above outdoor levels reflect the balance of exhaled breath by room occupants and ventilation. We developed a portable monitor to continuously sample carbon dioxide levels, which were combined with social contact diary records to estimate daily rebreathed litres. A pilot study established the practicality of monitor use up to 48-hours. We then estimated the daily volumes of air rebreathed by adolescents living in a crowded township. Results One hundred eight daily records were obtained from 63 adolescents aged between 12- and 20-years. Forty-five lived in wooden shacks and 18 in brick-built homes with a median household of 4 members (range 2–9). Mean daily volume of rebreathed air was 120.6 (standard error: 8.0) litres/day, with location contributions from household (48%), school (44%), visited households (4%), transport (0.5%) and other locations (3.4%). Independent predictors of daily rebreathed volumes included household type (p = 0.002), number of household occupants (p = 0.021), number of sleeping space occupants (p = 0.022) and winter season (p<0.001). Conclusions We demonstrated the practical measurement of carbon dioxide levels to which individuals are exposed in a sequence of non-steady state indoor environments. A novel metric of rebreathed air volume reflects social and environmental factors associated with airborne infection and can identify locations with high transmission potential.
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Affiliation(s)
- Robin Wood
- Desmond Tutu HIV Centre, Institute of Infectious Diseases and Molecular Medicine, and Department of Medicine, University of Cape Town Faculty of Health Sciences, Cape Town, South Africa
- * E-mail:
| | - Carl Morrow
- Desmond Tutu HIV Centre, Institute of Infectious Diseases and Molecular Medicine, and Department of Medicine, University of Cape Town Faculty of Health Sciences, Cape Town, South Africa
| | - Samuel Ginsberg
- Department of Electrical Engineering, Faculty of Engineering & the Built Environment, University of Cape Town, Cape Town, South Africa
| | - Elizabeth Piccoli
- Desmond Tutu HIV Centre, Institute of Infectious Diseases and Molecular Medicine, and Department of Medicine, University of Cape Town Faculty of Health Sciences, Cape Town, South Africa
| | - Darryl Kalil
- Desmond Tutu HIV Centre, Institute of Infectious Diseases and Molecular Medicine, and Department of Medicine, University of Cape Town Faculty of Health Sciences, Cape Town, South Africa
| | - Angelina Sassi
- Desmond Tutu HIV Centre, Institute of Infectious Diseases and Molecular Medicine, and Department of Medicine, University of Cape Town Faculty of Health Sciences, Cape Town, South Africa
| | - Rochelle P. Walensky
- Center for AIDS Research, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jason R. Andrews
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, United States of America
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Abstract
The global health community has set itself the task of eliminating tuberculosis (TB) as a public health problem by 2050. Although progress has been made in global TB control, the current decline in incidence of 2% yr(-1) is far from the rate needed to achieve this. If we are to succeed in this endeavour, new strategies to reduce the reservoir of latently infected persons (from which new cases arise) would be advantageous. However, ascertainment of the extent and risk posed by this group is poor. The current diagnostics tests (tuberculin skin test and interferon-gamma release assays) poorly predict who will develop active disease and the therapeutic options available are not optimal for the scale of the intervention that may be required. In this article, we outline a basis for our current understanding of latent TB and highlight areas where innovation leading to development of novel diagnostic tests, drug regimens and vaccines may assist progress. We argue that the pool of individuals at high risk of progression may be significantly smaller than the 2.33 billion thought to be immune sensitized by Mycobacterium tuberculosis and that identifying and targeting this group will be an important strategy in the road to elimination.
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Affiliation(s)
- H. Esmail
- Department of Medicine, Imperial College, London W2 1PG, UK
- Clinical Infectious Diseases Research Initiative, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Observatory 7925, South Africa
| | - C. E. Barry
- Tuberculosis Research Section, NIAID, NIH, Bethesda, MD 20892, USA
| | - D. B. Young
- Department of Medicine, Imperial College, London W2 1PG, UK
- MRC National Institute for Medical Research, London NW7 1AA, UK
| | - R. J. Wilkinson
- Department of Medicine, Imperial College, London W2 1PG, UK
- Clinical Infectious Diseases Research Initiative, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Observatory 7925, South Africa
- MRC National Institute for Medical Research, London NW7 1AA, UK
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Hatherill M, Geldenhuys H, Pienaar B, Suliman S, Chheng P, Debanne SM, Hoft DF, Boom WH, Hanekom WA, Johnson JL. Safety and reactogenicity of BCG revaccination with isoniazid pretreatment in TST positive adults. Vaccine 2014; 32:3982-8. [PMID: 24814553 DOI: 10.1016/j.vaccine.2014.04.084] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 04/22/2014] [Accepted: 04/24/2014] [Indexed: 02/08/2023]
Abstract
RATIONALE Global tuberculosis (TB) control may require mass vaccination with a new TB vaccine, such as a recombinant bacille Calmette Guerin (BCG) or attenuated Mycobacterium tuberculosis (MTB). The safety profile of live mycobacterial vaccines in latently infected adults with prior infant BCG vaccination is unknown. OBJECTIVES Evaluate safety and reactogenicity of BCG revaccination, with or without isoniazid (INH) pretreatment, in adults with latent MTB infection (LTBI). METHODS Eighty-two healthy, HIV uninfected, South African adults, with a BCG scar and tuberculin skin test (TST) diameter ≥ 15 mm, were randomized to receive 6 months of INH, starting either before, or 6 months after, intradermal revaccination with BCG Vaccine SSI (Statens Serum Institut, Copenhagen). Safety and reactogenicity data are reported through 3 months post BCG revaccination. RESULTS Baseline characteristics were similar between treatment arms. Mean baseline TST diameter was 20 ± 4 mm. Seventy-two subjects received BCG revaccination. Injection site erythema (68%) and induration (86%) peaked 1 week after revaccination. Ulceration (76%) peaked at 2 weeks, and resolved by 3 months in all but 3 subjects. Diameter of ulceration was >10mm in only 8%, but a residual scar was common (85%). No regional lymphadenitis or serious morbidity related to BCG was seen. Reactogenicity was not affected by INH pretreatment. CONCLUSION BCG revaccination of MTB infected adults is safe, well tolerated, and reactogenicity is similar to that of primary BCG vaccination. Clinical trials of live recombinant BCG or attenuated MTB vaccines may be considered in latently infected adults, with or without INH pretreatment (ClinicalTrials.gov identifier: NCT01119521).
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Affiliation(s)
- Mark Hatherill
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease & Molecular Medicine, School of Child & Adolescent Health, University of Cape Town, Cape Town, South Africa.
| | - Hendrik Geldenhuys
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease & Molecular Medicine, School of Child & Adolescent Health, University of Cape Town, Cape Town, South Africa
| | - Bernadette Pienaar
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease & Molecular Medicine, School of Child & Adolescent Health, University of Cape Town, Cape Town, South Africa
| | - Sara Suliman
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease & Molecular Medicine, School of Child & Adolescent Health, University of Cape Town, Cape Town, South Africa
| | - Phalkun Chheng
- Tuberculosis Research Unit, Department of Medicine, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, USA
| | - Sara M Debanne
- Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, OH, USA
| | - Daniel F Hoft
- Division of Immunobiology, Departments of Internal Medicine and Molecular Biology, Saint Louis University Medical Center, and Center for Vaccine Development, Saint Louis, MO, USA
| | - W Henry Boom
- Tuberculosis Research Unit, Department of Medicine, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, USA
| | - Willem A Hanekom
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease & Molecular Medicine, School of Child & Adolescent Health, University of Cape Town, Cape Town, South Africa
| | - John L Johnson
- Tuberculosis Research Unit, Department of Medicine, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, USA
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Hsu CY, Yen AMF, Chen LS, Chen HH. Surveillance of influenza from household to community in Taiwan. Trans R Soc Trop Med Hyg 2014; 108:213-20. [DOI: 10.1093/trstmh/tru023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Kasaie P, Andrews JR, Kelton WD, Dowdy DW. Timing of Tuberculosis Transmission and the Impact of Household Contact Tracing. An Agent-based Simulation Model. Am J Respir Crit Care Med 2014; 189:845-52. [DOI: 10.1164/rccm.201310-1846oc] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Dye C. Making wider use of the world's most widely used vaccine: Bacille Calmette-Guerin revaccination reconsidered. J R Soc Interface 2013; 10:20130365. [PMID: 23904584 PMCID: PMC3757998 DOI: 10.1098/rsif.2013.0365] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Approximately 100 million newborn children receive Bacille Calmette–Guérin (BCG) annually, because vaccination is consistently protective against childhood tuberculous meningitis and miliary TB. By contrast, BCG efficacy against pulmonary TB in children and adults is highly variable, ranging from 0% to 80%, though it tends to be higher in individuals who have no detectable prior exposure to mycobacterial infections, as judged by the absence of delayed-type hypersensitivity response (a negative tuberculin skin test, TST). The duration of protection against pulmonary TB is also variable, but lasts about 10 years on average. These observations raise the possibility that BCG revaccination, following primary vaccination in infancy, could be efficacious among TST-negative adolescents as they move into adulthood, the period of highest risk for pulmonary disease. To inform continuing debate about revaccination, this paper assesses the effectiveness and cost-effectiveness of revaccinating adolescents in a setting with intense transmission—Cape Town, South Africa. For a cost of revaccination in the range US$1–10 per person, and vaccine efficacy between 10% and 80% with protection for 10 years, the incremental cost per year of healthy life recovered (disability-adjusted life years, DALY) in the vaccinated population lies between US$116 and US$9237. The intervention is about twice as cost-effective when allowing for the extra benefits of preventing transmission, with costs per DALY recovered in the range US$52–$4540. At 80% efficacy, revaccination averted 17% of cases. Under the scenarios investigated, BCG revaccination is cost-effective against international benchmarks, though not highly effective. Cost-effectiveness ratios would be more favourable if we also allow for TB cases averted by preventing transmission to HIV-positive people, for the protection of HIV-negative people who later acquire HIV infection, for the possible non-specific benefits of BCG, for the fact that some adolescents would receive BCG for the first time, and for cost sharing when BCG is integrated into an adolescent immunization programme. These findings suggest, subject to further evaluation, that BCG revaccination could be cost-effective in some settings.
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Affiliation(s)
- Christopher Dye
- World Health Organization, Avenue Appia, CH1211 Geneva 27, Switzerland.
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Numminen E, Cheng L, Gyllenberg M, Corander J. Estimating the Transmission Dynamics ofStreptococcus pneumoniaefrom Strain Prevalence Data. Biometrics 2013; 69:748-57. [PMID: 23822205 DOI: 10.1111/biom.12040] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 02/01/2013] [Accepted: 02/01/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Elina Numminen
- Department of Mathematics and Statistics; University of Helsinki; P.O. Box 68, 00014 Helsinki Finland
| | - Lu Cheng
- Department of Mathematics and Statistics; University of Helsinki; P.O. Box 68, 00014 Helsinki Finland
| | - Mats Gyllenberg
- Department of Mathematics and Statistics; University of Helsinki; P.O. Box 68, 00014 Helsinki Finland
| | - Jukka Corander
- Department of Mathematics and Statistics; University of Helsinki; P.O. Box 68, 00014 Helsinki Finland
- Helsinki Institute for Information Technology; University of Helsinki; P.O. Box 68, 00014 Helsinki Finland
- Department of Mathematics; Åbo Akademi University; 20500 Åbo Finland
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Mills HL, Cohen T, Colijn C. Community-wide isoniazid preventive therapy drives drug-resistant tuberculosis: a model-based analysis. Sci Transl Med 2013; 5:180ra49. [PMID: 23576815 PMCID: PMC3714172 DOI: 10.1126/scitranslmed.3005260] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Tuberculosis (TB) control is especially difficult in settings of high HIV prevalence; HIV co-infection erodes host immunity and increases risk of progression to active TB. Studies have demonstrated that a 6-month (or longer) course of monotherapy with isoniazid [isoniazid preventive therapy (IPT)] can reduce this risk. The World Health Organization endorses IPT for symptom-free individuals with HIV/TB co-infection and has recommended expanding IPT to entire communities (community-wide IPT). Although previous reviews have not found a statistically significant elevated risk of isoniazid-resistant TB among individuals previously treated with IPT, community-wide IPT programs may nonetheless generate substantial selective pressure and increase the burden of drug-resistant TB (DRTB). We developed mathematical models to identify the conditions under which community-wide IPT interventions could increase the burden of isoniazid-resistant Mycobacterium tuberculosis, even when we assumed that IPT does not select for resistance among those treated with IPT. We found that in models that included any mechanism of interstrain competition (such as partial immunity conferred by a previous M. tuberculosis infection), community-wide IPT interventions conferred an indirect benefit to drug-resistant strains through selective suppression of drug-sensitive infections. This result suggests that the absence of an observed elevation in the risk of DRTB among those receiving IPT in small-scale studies of limited duration does not imply that the selective pressure imposed by community-wide IPT will not be substantial. Community-wide IPT may play an important role in TB control in these settings, and its rollout should be accompanied by interventions to detect and treat drug-resistant disease.
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Affiliation(s)
- Harriet L Mills
- Bristol Centre for Complexity Sciences, University of Bristol, Bristol BS8 1TR, UK
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Mixed-strain mycobacterium tuberculosis infections and the implications for tuberculosis treatment and control. Clin Microbiol Rev 2013; 25:708-19. [PMID: 23034327 DOI: 10.1128/cmr.00021-12] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Numerous studies have reported that individuals can simultaneously harbor multiple distinct strains of Mycobacterium tuberculosis. To date, there has been limited discussion of the consequences for the individual or the epidemiological importance of mixed infections. Here, we review studies that documented mixed infections, highlight challenges associated with the detection of mixed infections, and discuss possible implications of mixed infections for the diagnosis and treatment of patients and for the community impact of tuberculosis control strategies. We conclude by highlighting questions that should be resolved in order to improve our understanding of the importance of mixed-strain M. tuberculosis infections.
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Sergeev R, Colijn C, Murray M, Cohen T. Modeling the dynamic relationship between HIV and the risk of drug-resistant tuberculosis. Sci Transl Med 2012; 4:135ra67. [PMID: 22623743 PMCID: PMC3387814 DOI: 10.1126/scitranslmed.3003815] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The emergence of highly drug-resistant tuberculosis (TB) and interactions between TB and HIV epidemics pose serious challenges for TB control. Previous researchers have presented several hypotheses for why HIV-coinfected TB patients may suffer an increased risk of drug-resistant TB (DRTB) compared to other TB patients. Although some studies have found a positive association between an individual's HIV status and his or her subsequent risk of multidrug-resistant TB (MDRTB), the observed individual-level relationship between HIV and DRTB varies substantially among settings. Here, we develop a modeling framework to explore the effect of HIV on the dynamics of DRTB. The model captures the acquisition of resistance to important classes of TB drugs, imposes fitness costs associated with resistance-conferring mutations, and allows for subsequent restoration of fitness because of compensatory mutations. Despite uncertainty in several key parameters, we demonstrate epidemic behavior that is robust over a range of assumptions. Whereas HIV facilitates the emergence of MDRTB within a community over several decades, HIV-seropositive individuals presenting with TB may, counterintuitively, be at lower risk of drug-resistant TB at early stages of the co-epidemic. This situation arises because many individuals with incident HIV infection will already harbor latent Mycobacterium tuberculosis infection acquired at an earlier time when drug resistance was less prevalent. We find that the rise of HIV can increase the prevalence of MDRTB within populations even as it lowers the average fitness of circulating MDRTB strains compared to similar populations unaffected by HIV. Preferential social mixing among individuals with similar HIV status and lower average CD4 counts among HIV-seropositive individuals further increase the expected burden of MDRTB. This model suggests that the individual-level association between HIV and drug-resistant forms of TB is dynamic, and therefore, cross-sectional studies that do not report a positive individual-level association will not provide assurance that HIV does not exacerbate the burden of resistant TB in the community.
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Affiliation(s)
- Rinat Sergeev
- Department of Medicine, Brigham and Women's Hospital, 641 Huntington Ave, 02115, Boston, MA, USA
- Department of Microelectronics, Ioffe Institute, 26 Polytekhnicheskaya, St Petersburg 194021, Russia
| | - Caroline Colijn
- Department of Mathematics, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - Megan Murray
- Department of Medicine, Brigham and Women's Hospital, 641 Huntington Ave, 02115, Boston, MA, USA
- Department of Epidemiology, Harvard School of Public Health, 641 Huntington Ave, 02115, Boston, MA, USA
| | - Ted Cohen
- Department of Medicine, Brigham and Women's Hospital, 641 Huntington Ave, 02115, Boston, MA, USA
- Department of Epidemiology, Harvard School of Public Health, 641 Huntington Ave, 02115, Boston, MA, USA
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Andrews JR, Noubary F, Walensky RP, Cerda R, Losina E, Horsburgh CR. Risk of progression to active tuberculosis following reinfection with Mycobacterium tuberculosis. Clin Infect Dis 2012; 54:784-91. [PMID: 22267721 DOI: 10.1093/cid/cir951] [Citation(s) in RCA: 236] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The risk of progression to active tuberculosis is greatest in the several years following initial infection. The extent to which latent tuberculosis infection reduces the risk of progressive disease following reexposure and reinfection is not known. Indirect estimates from population models have been highly variable. METHODS We reviewed prospective cohort studies of persons exposed to individuals with infectious tuberculosis that were published prior to the widespread treatment of latent tuberculosis to estimate the incidence of tuberculosis among individuals with latent tuberculosis infection (LTBI group) and without latent tuberculosis (uninfected; UI group). We calculated the incidence rate ratio (IRR) of tuberculosis disease following infection between these 2 groups. We then adjusted incidence for expected reactivation, proportion of each group that was infected, and median time of observation following infection during the study. RESULTS We identified 18 publications reporting tuberculosis incidence among 23 paired cohorts of individuals with and without latent infection (total N = 19 886). The weighted mean adjusted incidence rate of tuberculosis in the LTBI and UI groups attributable to reinfection was 13.5 per 1000 person-years (95% confidence interval [CI]: 5.0-26.2 per 1000 person-years) and that attributable to primary infection was 60.1 per 1000 person-years (95% CI: 38.6-87.4 per 1000 person-years). The adjusted IRR for tuberculosis in the LTBI group compared with the UI group was 0.21 (95% CI: .14-.30). CONCLUSIONS Individuals with latent tuberculosis had 79% lower risk of progressive tuberculosis after reinfection than uninfected individuals. The risk reduction estimated in this study is greater than most previous estimates made through population models.
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Affiliation(s)
- Jason R Andrews
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
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