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Huang G, Xu Z, Bai L, Liu J, Yu S, Yao H. Spatiotemporal analysis of tuberculosis in the Hunan Province, China, 2014-2022. Front Public Health 2024; 12:1426503. [PMID: 39175902 PMCID: PMC11338757 DOI: 10.3389/fpubh.2024.1426503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Accepted: 07/30/2024] [Indexed: 08/24/2024] Open
Abstract
Background Pulmonary tuberculosis (PTB) is a major infectious disease that threatens human health. China is a high tuberculosis-burden country and the Hunan Province has a high tuberculosis notification rate. However, no comprehensive analysis has been conducted on the spatiotemporal distribution of PTB in the Hunan Province. Therefore, this study investigated the spatiotemporal distribution of PTB in the Hunan Province to enable targeted control policies for tuberculosis. Methods We obtained data about cases of PTB in the Hunan Province notified from January 2014 to December 2022 from the China Information System for Disease Control and Prevention. Time-series analysis was conducted to analyze the trends in PTB case notifications. Spatial autocorrelation analysis was conducted to detect the spatial distribution characteristics of PTB at a county level in Hunan Province. Space-time scan analysis was conducted to confirm specific times and locations of PTB clustering. Results A total of 472,826 new cases of PTB were notified in the Hunan Province during the 9-year study period. The mean PTB notification rate showed a gradual, fluctuating downward trend over time. The number of PTB notifications per month showed significant seasonal variation, with an annual peak in notifications in January or March, followed by a fluctuating decline after March, reaching a trough in November or December. Moran's I index of spatial autocorrelation revealed that the notification rate of PTB by county ranged from 0.117 to 0.317 during the study period, indicating spatial clustering. The hotspot areas of PTB were mainly concentrated in the Xiangxi Autonomous Prefecture, Zhangjiajie City, and Hengyang City. The most likely clustering region was identified in the central-southern part of the province, and a secondary clustering region was identified in the northwest part of the province. Conclusion This study identified the temporal trend and spatial distribution pattern of tuberculosis in the Hunan Province. PTB clustered mainly in the central-southern and northwestern regions of the province. Disease control programs should focus on strengthening tuberculosis control in these regions.
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Affiliation(s)
- Guojun Huang
- Chinese Center for Disease Control and Prevention, Beijing, China
- Department of Science and Education, Hunan Chest Hospital, Changsha, China
| | - Zuhui Xu
- Department of Tuberculosis Control and Prevention, Hunan Chest Hospital, Changsha, China
| | | | - Jianjun Liu
- Chinese Center for Disease Control and Prevention, Beijing, China
| | - Shicheng Yu
- Chinese Center for Disease Control and Prevention, Beijing, China
| | - Hongyan Yao
- Chinese Center for Disease Control and Prevention, Beijing, China
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2
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Chawla H, Anand P, Garg K, Bhagat N, Varmani SG, Bansal T, McBain AJ, Marwah RG. A comprehensive review of microbial contamination in the indoor environment: sources, sampling, health risks, and mitigation strategies. Front Public Health 2023; 11:1285393. [PMID: 38074709 PMCID: PMC10701447 DOI: 10.3389/fpubh.2023.1285393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 10/25/2023] [Indexed: 12/18/2023] Open
Abstract
The quality of the indoor environment significantly impacts human health and productivity, especially given the amount of time individuals spend indoors globally. While chemical pollutants have been a focus of indoor air quality research, microbial contaminants also have a significant bearing on indoor air quality. This review provides a comprehensive overview of microbial contamination in built environments, covering sources, sampling strategies, and analysis methods. Microbial contamination has various origins, including human occupants, pets, and the outdoor environment. Sampling strategies for indoor microbial contamination include air, surface, and dust sampling, and various analysis methods are used to assess microbial diversity and complexity in indoor environments. The review also discusses the health risks associated with microbial contaminants, including bacteria, fungi, and viruses, and their products in indoor air, highlighting the need for evidence-based studies that can relate to specific health conditions. The importance of indoor air quality is emphasized from the perspective of the COVID-19 pandemic. A section of the review highlights the knowledge gap related to microbiological burden in indoor environments in developing countries, using India as a representative example. Finally, potential mitigation strategies to improve microbiological indoor air quality are briefly reviewed.
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Affiliation(s)
- Hitikk Chawla
- Institute for Cell Biology and Neuroscience, Goethe University Frankfurt, Frankfurt, Germany
| | - Purnima Anand
- Department of Microbiology, Bhaskaracharya College of Applied Sciences, University of Delhi, New Delhi, India
| | - Kritika Garg
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, India
| | - Neeru Bhagat
- Department of Microbiology, Bhaskaracharya College of Applied Sciences, University of Delhi, New Delhi, India
| | - Shivani G. Varmani
- Department of Biomedical Science, Bhaskaracharya College of Applied Sciences, University of Delhi, New Delhi, India
| | - Tanu Bansal
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
| | - Andrew J. McBain
- School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Ruchi Gulati Marwah
- Department of Microbiology, Bhaskaracharya College of Applied Sciences, University of Delhi, New Delhi, India
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3
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Strydom D, le Roux JD, Craig IK. State estimation for nonlinear state-space transmission models of tuberculosis. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2023; 43:339-357. [PMID: 35165919 DOI: 10.1111/risa.13901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Given the high prevalence of tuberculosis (TB) and the mortality rate associated with the disease, numerous models, such as the Gammaitoni and Nucci (GN) model, were developed to model the risk of transmission. These models typically rely on a quanta generation rate as a measurement of infectivity. Since the quanta generation rate cannot be measured directly, the unique contribution of this work is to develop state estimators to estimate the quanta generation rate from available measurements. To estimate the quanta generation rate, the GN model is adapted into an augmented single-room GN model and a simplified two-room GN model. Both models are shown to be observable, i.e., it is theoretically possible to estimate the quanta generation rate given available measurements. Kalman filters are used to estimate the quanta generation rate. First, a continuous-time extended Kalman filter is used for both adapted models using a simulation and measurement sampling rate of 60 s. Accurate quanta generate rate estimates are achieved in both cases. A more realistic scenario is also considered with a measurement sampling rate of one day. For these estimates, a hybrid extended Kalman filter (HEKF) is used. Accurate quanta generation rate estimates are achieved for the more realistic scenario. Future work could potentially use the HEKFs, the adapted models, and real-time measurements in a control system feedback loop to reduce the transmission of TB in confined spaces such as hospitals.
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Affiliation(s)
- Duayne Strydom
- Department of Electrical, Electronic and Computer Engineering, University of Pretoria, South Africa
| | - Johan Derik le Roux
- Department of Electrical, Electronic and Computer Engineering, University of Pretoria, South Africa
| | - Ian Keith Craig
- Department of Electrical, Electronic and Computer Engineering, University of Pretoria, South Africa
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4
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Messina G, Amodeo D, Taddeini F, De Palma I, Puccio A, Cevenini G. Wind of change: Better air for microbial environmental control. CASE STUDIES IN CHEMICAL AND ENVIRONMENTAL ENGINEERING 2022; 6:100240. [PMID: 37520926 PMCID: PMC9339158 DOI: 10.1016/j.cscee.2022.100240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/22/2022] [Accepted: 07/25/2022] [Indexed: 08/01/2023]
Abstract
Background The COVID19 epidemic highlighted the importance of air in the transmission of pathogens. Air disinfection is one of the key points to reduce the risk of transmission both in the health sector and in public, civil and industrial environments. All bacteria and viruses tested to date can be inactivated by UV-C rays. Laboratory tested UV-C systems are increasingly popular and proposed as effective technologies for air purification; few studies have evaluated their performance in populated indoor environments. The aim of this investigation was to evaluate the effectiveness of a UV-C disinfection system for air in a real working context. Methods This experimental study was conducted between December 2020 and February 2021 in an office of the Department of Molecular and Developmental Medicine of the University of Siena, Italy. A pre-final version air purifier (Cleaning Air T12), capable of treating 210 m3/h of air, was first tested for its ability to filter particulates and reduce microbial air contamination in the absence of people. Subsequently, the experiments were conducted in the presence of 3-5 subjects who worked for several hours in an office. During the tests, microbiological samples of air were collected in real time, switching the system on and off periodically. Air samples were collected and incubated on Petri dishes at 36 °C and 22 °C. Statistical analysis was performed with Stata 16 software assuming a significance level of 95%. An interpolating model was identified to describe the dynamics of contamination reduction when the device operates. Results Preliminary tests showed a significant 62.5% reduction in Colony-Forming Units (CFUs) with 36 °C incubation. Reductions in the particulate component were also observed. In the main test, comparison of CFU data, between the device-on phase (90 min) and the subsequent device-off phase (60 min), showed statistically significant increase (p = 0.001) of environmental contamination passing from a mean of 86.6 (65.8-107.4) to 171.1 (143.9-198.3) CFU/m3, that is a rise of about 100%. The interpolating model exhibited a good fit of CFU reduction trend with the device on. Conclusions The system, which mainly uses UV-C lamps for disinfection, was able to significantly reduce environmental and human contamination in real time. Experimental tests have shown that as soon as the device is switched off, after at least half an hour of operation, the healthiness of the air decreases drastically within 10 minutes, bringing the airborne microbial contamination (induced by the presence of operators in the environment) to levels even higher than 150% of the last value with the device on. Re-engineering strategies for system improvement were also discussed.
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Affiliation(s)
- G Messina
- Post Graduate School of Public Health, University of Siena, Italy
- Department of Molecular and Developmental Medicine, University of Siena, Italy
| | - D Amodeo
- Department of Molecular and Developmental Medicine, University of Siena, Italy
| | - F Taddeini
- Post Graduate School of Public Health, University of Siena, Italy
| | - I De Palma
- Department of Molecular and Developmental Medicine, University of Siena, Italy
| | - A Puccio
- Department of Medical Biotechnologies, Bioengineering Lab, University of Siena, Italy
| | - G Cevenini
- Department of Medical Biotechnologies, Bioengineering Lab, University of Siena, Italy
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5
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Zhang H, Liu M, Fan W, Sun S, Fan X. The impact of Mycobacterium tuberculosis complex in the environment on one health approach. Front Public Health 2022; 10:994745. [PMID: 36159313 PMCID: PMC9489838 DOI: 10.3389/fpubh.2022.994745] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 08/18/2022] [Indexed: 01/26/2023] Open
Abstract
Tuberculosis caused by the Mycobacterium tuberculosis complex (MTBC) has become one of the leading causes of death in humans and animals. Current research suggests that the transmission of MTBC in the environment indirectly transmit to humans and animals with subsequent impact on their wellbeing. Therefore, it is of great significance to take One Health approach for understanding the role of MTBC in not only the interfaces of humans and animals, but also environment, including soil, water, pasture, air, and dust, etc., in response to the MTBC infection. In this review, we present the evidence of MTBC transmission from environment, as well as detection and control strategies in this interface, seeking to provide academic leads for the global goal of End Tuberculosis Strategy under multidisciplinary and multisectoral collaborations.
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6
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Conzatti A, Kershaw T, Copping A, Coley D. A review of the impact of shelter design on the health of displaced populations. JOURNAL OF INTERNATIONAL HUMANITARIAN ACTION 2022; 7:18. [PMID: 37519834 PMCID: PMC9425791 DOI: 10.1186/s41018-022-00123-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 06/22/2022] [Indexed: 08/01/2023]
Abstract
There are currently millions of displaced people encamped in low-quality shelters that jeopardise the health of these displaced populations. These shelters, which exhibit poor thermal regulation and air quality, are often inhabited by households for several years. Recently, the internal environment of shelters has been recognised as a determinant of the health of the occupants and the indoor air quality (IAQ) and internal temperatures have been identified as critical factors affecting occupants' health. Attempts by researchers and private companies to develop healthier shelter solutions have mainly prioritised factors such as rapid deployment, transportability and sustainability. Via a systematic bibliometric analysis of the existing literature, this review examines the impact of shelters' internal environment on occupant health. Self-reports and building simulation are the most common methodologies reported in the literature, but there is a disconnect between the reported shelter issues and their impact on health. This is likely due to the multifaceted and site-specific factors analysed. Indoor air quality, thermal comfort and overcrowding are the most commonly identified shelter issues, which are strongly related to the presence of infectious and airborne diseases. An analysis of the available literature indicates that there is still a lack of clear guidance linking shelter quality to health. Moreover, evidence of the impact of shelters on health is harder to find, and there is a gap regarding the metrics and the methodology used to evaluate shelter quality. Therefore, further research is necessary to provide evidence of the impact of shelter design on health through transdisciplinary approaches.
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Affiliation(s)
- Anna Conzatti
- Department of Architecture and Civil Engineering, University of Bath, Claverton Down, Bat, UK
| | - Tristan Kershaw
- Department of Architecture and Civil Engineering, University of Bath, Claverton Down, Bat, UK
| | - Alexander Copping
- Department of Architecture and Civil Engineering, University of Bath, Claverton Down, Bat, UK
| | - David Coley
- Department of Architecture and Civil Engineering, University of Bath, Claverton Down, Bat, UK
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7
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Zhang Y, Hui FKP, Duffield C, Saeed AM. A review of facilities management interventions to mitigate respiratory infections in existing buildings. BUILDING AND ENVIRONMENT 2022; 221:109347. [PMID: 35782231 PMCID: PMC9238148 DOI: 10.1016/j.buildenv.2022.109347] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 05/01/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023]
Abstract
The Covid-19 pandemic reveals that the hazard of the respiratory virus was a secondary consideration in the design, development, construction, and management of public and commercial buildings. Retrofitting such buildings poses a significant challenge for building owners and facilities managers. This article reviews current research and practices in building operations interventions for indoor respiratory infection control from the perspective of facilities managers to assess the effectiveness of available solutions. This review systematically selects and synthesises eighty-six articles identified through the PRISMA process plus supplementary articles identified as part of the review process, that deal with facilities' operations and maintenance (O&M) interventions. The paper reviewed the context, interventions, mechanisms, and outcomes discussed in these articles, concluding that interventions for respiratory virus transmission in existing buildings fall into three categories under the Facilities Management (FM) discipline: Hard services (HVAC and drainage system controls) to prevent aerosol transmissions, Soft Services (cleaning and disinfection) to prevent fomite transmissions, and space management (space planning and occupancy controls) to eliminate droplet transmissions. Additionally, the research emphasised the need for FM intervention studies that examine occupant behaviours with integrated intervention results and guide FM intervention decision-making. This review expands the knowledge of FM for infection control and highlights future research opportunities.
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Affiliation(s)
- Yan Zhang
- Department of Infrastructure Engineering, University of Melbourne, Level 6, Building 290, 700 Swanston Street, Carlton, Victoria, Australia
| | - Felix Kin Peng Hui
- Department of Infrastructure Engineering, University of Melbourne, Australia
| | - Colin Duffield
- Department of Infrastructure Engineering, University of Melbourne, Australia
| | - Ali Mohammed Saeed
- Department of Jobs, Regions and Precincts, Level 13, 1 Spring Street, Melbourne, Victoria, Australia
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8
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Izadyar N, Miller W. Ventilation strategies and design impacts on indoor airborne transmission: A review. BUILDING AND ENVIRONMENT 2022; 218:109158. [PMID: 35573806 PMCID: PMC9075988 DOI: 10.1016/j.buildenv.2022.109158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 04/26/2022] [Accepted: 04/29/2022] [Indexed: 06/15/2023]
Abstract
The COVID-19 outbreak has brought the indoor airborne transmission issue to the forefront. Although ventilation systems provide clean air and dilute indoor contaminated air, there is strong evidence that airborne transmission is the main route for contamination spread. This review paper aims to critically investigate ventilation impacts on particle spread and identify efficient ventilation strategies in controlling aerosol distribution in clinical and non-clinical environments. This article also examines influential ventilation design features (i.e., exhaust location) affecting ventilation performance in preventing aerosols spread. This paper shortlisted published documents for a review based on identification (keywords), pre-processing, screening, and eligibility of these articles. The literature review emphasizes the importance of ventilation systems' design and demonstrates all strategies (i.e., mechanical ventilation) could efficiently remove particles if appropriately designed. The study highlights the need for occupant-based ventilation systems, such as personalized ventilation instead of central systems, to reduce cross-infections. The literature underlines critical impacts of design features like ventilation rates and the number and location of exhausts and suggests designing systems considering airborne transmission. This review underpins that a higher ventilation rate should not be regarded as a sole indicator for designing ventilation systems because it cannot guarantee reducing risks. Using filtration and decontamination devices based on building functionalities and particle sizes can also increase ventilation performance. This paper suggests future research on optimizing ventilation systems, particularly in high infection risk spaces such as multi-storey hotel quarantine facilities. This review contributes to adjusting ventilation facilities to control indoor aerosol transmission.
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Affiliation(s)
- Nima Izadyar
- School of Built Environment, College of Engineering and Science, Victoria University, Melbourne, VIC, Australia
| | - Wendy Miller
- School of Architecture & Built Environment, Science and Engineering Faculty, Queensland University of Technology (QUT), Brisbane, QLD, 4001, Australia
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9
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Nguyen TT, Johnson GR, Bell SC, Knibbs LD. A Systematic Literature Review of Indoor Air Disinfection Techniques for Airborne Bacterial Respiratory Pathogens. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19031197. [PMID: 35162224 PMCID: PMC8834760 DOI: 10.3390/ijerph19031197] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 02/06/2023]
Abstract
Interrupting the transmission of airborne (<≈5 µm) respiratory pathogens indoors is not a new challenge, but it has attracted unprecedented interest due to the COVID-19 pandemic during 2020–2021. However, bacterial respiratory pathogens with known or potential airborne transmission account for an appreciable proportion of the communicable disease burden globally. We aimed to systematically review quantitative, laboratory-based studies of air disinfection techniques for airborne respiratory bacteria. Three databases (PubMed, Web of Science, Scopus) were searched, following PRISMA guidelines. A total of 9596 articles were identified, of which 517 were assessed in detail and of which 26 met the inclusion and quality assessment criteria. Seven air disinfection techniques, including UV-C light, filtration, and face masks, among others, were applied to 13 different bacterial pathogens. More than 80% of studies suggested that air disinfection techniques were more effective at inactivating or killing bacteria than the comparator or baseline condition. However, it was not possible to compare these techniques because of methodological heterogeneity and the relatively small number of the studies. Laboratory studies are useful for demonstrating proof-of-concept and performance under controlled conditions. However, the generalisability of their findings to person-to-person transmission in real-world settings is unclear for most of the pathogens and techniques we assessed.
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Affiliation(s)
- Thi Tham Nguyen
- School of Public Health, The University of Queensland, Herston, QLD 4006, Australia;
- Correspondence:
| | - Graham R. Johnson
- School of Earth and Atmospheric Sciences, Queensland University of Technology, Brisbane, QLD 4000, Australia;
| | - Scott C. Bell
- Children’s Health Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, QLD 4101, Australia;
- Adult Cystic Fibrosis Centre, The Prince Charles Hospital, Chermside, QLD 4032, Australia
- Translational Research Institute, Brisbane, QLD 4102, Australia
| | - Luke D. Knibbs
- School of Public Health, The University of Queensland, Herston, QLD 4006, Australia;
- Faculty of Medicine and Health, School of Public Health, The University of Sydney, Sydney, NSW 2006, Australia
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10
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Islam MS, Banu S, Tarannum S, Chowdhury KIA, Nazneen A, Islam MT, Shafique SMZ, Islam SMH, Chughtai AA, Seale H. Examining pulmonary TB patient management and healthcare workers exposures in two public tertiary care hospitals, Bangladesh. PLOS GLOBAL PUBLIC HEALTH 2022; 2:e0000064. [PMID: 36962098 PMCID: PMC10021262 DOI: 10.1371/journal.pgph.0000064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 11/23/2021] [Indexed: 11/18/2022]
Abstract
Implementation of tuberculosis (TB) infection prevention and control (IPC) guidelines in public tertiary care general hospitals remain challenging due to limited evidence of pulmonary TB (PTB) patients' duration of hospital stay and management. To fill this evidence gap, this study examined adult PTB patient management, healthcare workers' (HCWs) exposures and IPC practices in two public tertiary care hospitals in Bangladesh.Between December 2017 and September 2019, a multidisciplinary team conducted structured observations, a hospital record review, and in-depth interviews with hospital staff from four adult medicine wards.Over 20 months, we identified 1,200 presumptive TB patients through the hospital record review, of whom 263 were confirmed PTB patients who stayed in the hospital, a median of 4.7 days without TB treatment and possibly contaminated the inpatients wards. Over 141 observation hours, we found a median of 3.35 occupants present per 10 m2 of floor space and recorded a total of 17,085 coughs and 316 sneezes: a median of 3.9 coughs or sneezes per 10 m2 per hour per ward. Only 8.4% of coughs and 21% of sneezes were covered by cloths, paper, tissues, or by hand. The HCWs reportedly could not isolate the TB patients due to limited resources and space and could not provide them with a mask. Further, patients and HCWs did not wear any respirators.The study identified that most TB patients stayed in the hospitals untreated for some duration of time. These PTB patients frequently coughed and sneezed without any facial protection that potentially contaminated the ward environment and put everyone, including the HCWs, at risk of TB infection. Interventions that target TB patients screening on admission, isolation of presumptive TB patients, respiratory hygiene, and HCWs' use of personal protective equipment need to be enhanced and evaluated for acceptability, practicality and scale-up.
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Affiliation(s)
- Md Saiful Islam
- Emerging Infections Program, Infectious Diseases Division, icddr,b, Dhaka, Bangladesh
- School of Population Health, Faculty of Medicine and Health, University of New South Wales, Sydney, Australia
| | - Sayera Banu
- Emerging Infections Program, Infectious Diseases Division, icddr,b, Dhaka, Bangladesh
| | - Sayeeda Tarannum
- Emerging Infections Program, Infectious Diseases Division, icddr,b, Dhaka, Bangladesh
| | | | - Arifa Nazneen
- Emerging Infections Program, Infectious Diseases Division, icddr,b, Dhaka, Bangladesh
| | | | - S M Zafor Shafique
- Emerging Infections Program, Infectious Diseases Division, icddr,b, Dhaka, Bangladesh
| | - S M Hasibul Islam
- Emerging Infections Program, Infectious Diseases Division, icddr,b, Dhaka, Bangladesh
| | - Abrar Ahmad Chughtai
- School of Population Health, Faculty of Medicine and Health, University of New South Wales, Sydney, Australia
| | - Holly Seale
- School of Population Health, Faculty of Medicine and Health, University of New South Wales, Sydney, Australia
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11
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Vlachokostas A, Burns CA, Salsbury TI, Daniel RC, James DP, Flaherty JE, Wang N, Underhill RM, Kulkarni G, Pease LF. Experimental evaluation of respiratory droplet spread to rooms connected by a central ventilation system. INDOOR AIR 2022; 32:e12940. [PMID: 35048430 DOI: 10.1111/ina.12940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/20/2021] [Accepted: 09/24/2021] [Indexed: 06/14/2023]
Abstract
This article presents results from an experimental study to ascertain the transmissibility of the SARS-CoV-2 virus between rooms in a building that are connected by a central ventilation system. Respiratory droplet surrogates made of mucus and virus mimics were released in one room in a test building, and measurements of concentration levels were made in other rooms connected via the ventilation system. The paper presents experimental results for different ventilation system configurations, including ventilation rate, filtration level (up to MERV-13), and fractional outdoor air intake. The most important finding is that respiratory droplets can and do transit through central ventilation systems, suggesting a mechanism for viral transmission (and COVID-19 specifically) within the built environment in reasonable agreement with well-mixed models. We also find the deposition of small droplets (0.5-4 μm) on room walls to be negligibly small.
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Affiliation(s)
- Alex Vlachokostas
- Pacific Northwest National Laboratory (PNNL), Richland, Washington, USA
| | - Carolyn A Burns
- Pacific Northwest National Laboratory (PNNL), Richland, Washington, USA
| | | | - Richard C Daniel
- Pacific Northwest National Laboratory (PNNL), Richland, Washington, USA
| | - Daniel P James
- Pacific Northwest National Laboratory (PNNL), Richland, Washington, USA
| | - Julia E Flaherty
- Pacific Northwest National Laboratory (PNNL), Richland, Washington, USA
| | - Na Wang
- Pacific Northwest National Laboratory (PNNL), Richland, Washington, USA
| | | | - Gourihar Kulkarni
- Pacific Northwest National Laboratory (PNNL), Richland, Washington, USA
| | - Leonard F Pease
- Pacific Northwest National Laboratory (PNNL), Richland, Washington, USA
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12
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Bueno de Mesquita PJ, Delp WW, Chan WR, Bahnfleth WP, Singer BC. Control of airborne infectious disease in buildings: Evidence and research priorities. INDOOR AIR 2022; 32:e12965. [PMID: 34816493 DOI: 10.1111/ina.12965] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 10/07/2021] [Accepted: 11/11/2021] [Indexed: 06/13/2023]
Abstract
The evolution of SARS-CoV-2 virus has resulted in variants likely to be more readily transmitted through respiratory aerosols, underscoring the increased potential for indoor environmental controls to mitigate risk. Use of tight-fitting face masks to trap infectious aerosol in exhaled breath and reduce inhalation exposure to contaminated air is of critical importance for disease control. Administrative controls including the regulation of occupancy and interpersonal spacing are also important, while presenting social and economic challenges. Indoor engineering controls including ventilation, exhaust, air flow control, filtration, and disinfection by germicidal ultraviolet irradiation can reduce reliance on stringent occupancy restrictions. However, the effects of controls-individually and in combination-on reducing infectious aerosol transfer indoors remain to be clearly characterized to the extent needed to support widespread implementation by building operators. We review aerobiologic and epidemiologic evidence of indoor environmental controls against transmission and present a quantitative aerosol transfer scenario illustrating relative differences in exposure at close-interactive, room, and building scales. We identify an overarching need for investment to implement building controls and evaluate their effectiveness on infection in well-characterized and real-world settings, supported by specific, methodological advances. Improved understanding of engineering control effectiveness guides implementation at scale while considering occupant comfort, operational challenges, and energy costs.
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Affiliation(s)
| | - William W Delp
- Indoor Environment Group, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Wanyu R Chan
- Indoor Environment Group, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - William P Bahnfleth
- Department of Architectural Engineering, Pennsylvania State University, State College, Pennsylvania, USA
| | - Brett C Singer
- Indoor Environment Group, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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13
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Bu Y, Ooka R, Kikumoto H, Oh W. Recent research on expiratory particles in respiratory viral infection and control strategies: A review. SUSTAINABLE CITIES AND SOCIETY 2021; 73:103106. [PMID: 34306994 PMCID: PMC8272400 DOI: 10.1016/j.scs.2021.103106] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 06/07/2021] [Accepted: 06/15/2021] [Indexed: 05/15/2023]
Abstract
The global spread of coronavirus disease 2019 poses a significant threat to human health. In this study, recent research on the characteristics of expiratory particles and flow is reviewed, with a special focus on different respiratory activities, to provide guidance for reducing the viral infection risk in the built environment. Furthermore, environmental influence on particle evaporation, dispersion, and virus viability after exhalation and the current methods for infection risk assessment are reviewed. Finally, we summarize promising control strategies against infectious expiratory particles. The results show that airborne transmission is a significant viral transmission route, both in short and long ranges, from infected individuals. Relative humidity affects the evaporation and trajectories of middle-sized droplets most, and temperature accelerates the inactivation of SARS-CoV-2 both on surfaces and in aerosols. Future research is needed to improve infection risk models to better predict the infection potential of different transmission routes. Moreover, further quantitative studies on the expiratory flow features after wearing a mask are needed. Systematic investigations and the design of advanced air distribution methods, portable air cleaners, and ultraviolet germicidal irradiation systems, which have shown high efficacy in removing contaminants, are required to better control indoor viral infection.
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Affiliation(s)
- Yunchen Bu
- Graduate School of Engineering, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Ryozo Ooka
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Hideki Kikumoto
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Wonseok Oh
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
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14
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Hou M, Pantelic J, Aviv D. Spatial analysis of the impact of UVGI technology in occupied rooms using ray-tracing simulation. INDOOR AIR 2021; 31:1625-1638. [PMID: 33772881 DOI: 10.1111/ina.12827] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/25/2021] [Accepted: 03/14/2021] [Indexed: 06/12/2023]
Abstract
The use of Ultraviolet Germicidal Irradiation (UVGI) devices in the upper zones of occupied buildings has gained increased attention as one of the most effective mitigation technologies for the transmission of COVID-19. To ensure safe and effective use of upper-room UVGI, it is necessary to devise a simulation technique that enables engineers, designers, and users to explore the impact of different design and operational parameters. We have developed a simulation technique for calculating UV-C fluence rate within the volume of the upper zone and planar irradiance in the lower occupied zone. Our method is based on established ray-tracing light simulation methods adapted to the UV-C wavelength range. We have included a case study of a typical hospital patient room. In it, we explored the impact of several design parameters: ceiling height, device location, room configuration, proportions, and surface materials. We present a spatially mapped parametric study of the UV-C irradiance distribution in three dimensions. We found that the ceiling height and mounting height of the UVGI fixtures combined can cause the largest variation (up to 22%) in upper zone fluence rate. One of the most important findings of this study is that it is crucial to consider interreflections in the room. This is because surface reflectance is the design parameter with the largest impact on the occupant exposure in the lower zone: Applying materials with high reflectance ratio in the upper portion of the room has the highest negative impact (over 700% variation) on increasing hot spots that may receive over 6 mJ/cm2 UV dose in the lower occupied zone.
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Affiliation(s)
- Miaomiao Hou
- University of Pennsylvania, Philadelphia, PA, USA
- Tongji University, Shanghai, China
| | - Jovan Pantelic
- University of California, Berkeley, CA, USA
- KU Leuven, Leuven, Belgium
| | - Dorit Aviv
- University of Pennsylvania, Philadelphia, PA, USA
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15
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Nardell EA. Air Disinfection for Airborne Infection Control with a Focus on COVID-19: Why Germicidal UV is Essential †. Photochem Photobiol 2021; 97:493-497. [PMID: 33759191 PMCID: PMC8251047 DOI: 10.1111/php.13421] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 03/16/2021] [Indexed: 01/03/2023]
Abstract
Aerosol transmission is now widely accepted as the principal way that COVID-19 is spread, as has the importance of ventilation-natural and mechanical. But in other than healthcare facilities, mechanical ventilation is designed for comfort, not airborne infection control, and cannot achieve the 6 to 12 room air changes per hour recommended for airborne infection control. More efficient air filters have been recommended in ventilation ducts despite a lack of convincing evidence that SARS-CoV-2 virus spreads through ventilation systems. Most transmission appears to occur in rooms where both an infectious source COVID-19 case and other susceptible occupants share the same air. Only two established room-based technologies are available to supplement mechanical ventilation: portable room air cleaners and upper room germicidal UV air disinfection. Portable room air cleaners can be effective, but performance is limited by their clean air delivery rate relative to room volume. SARS-CoV-2 is highly susceptible to GUV, an 80-year-old technology that has been shown to safely, quietly, effectively and economically produce the equivalent of 10 to 20 or more air changes per hour under real life conditions. For these reasons, upper room GUV is the essential engineering intervention for reducing COVID-19 spread.
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Affiliation(s)
- Edward A. Nardell
- Division of Global Health EquityBrigham & Women’s HospitalHarvard Medical SchoolBostonMAUSA
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16
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Volchenkov G. Experience with UV-C Air Disinfection in Some Russian Hospitals †. Photochem Photobiol 2021; 97:549-551. [PMID: 33728645 PMCID: PMC8250548 DOI: 10.1111/php.13418] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 03/12/2021] [Indexed: 11/28/2022]
Abstract
Although the environmental control measure of ultraviolet germicidal irradiation (UVGI) for disinfection has not been widely used in the United States and some parts of the world in the past few decades, this technology has been well applied in Russia. UVGI technology has been particularly useful with regard to limiting TB transmission in medical facilities. There is good evidence that UV‐C (180−280 nm) air disinfection can be a helpful intervention in reducing transmission of the SARS‐CoV‐2 virus.
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17
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Zellweger JP, Zellweger-Landry A, Egger JM, Koller-Doser A, Schmidt AJ. Surveillance of Employees of Swiss Federal Asylum Centres for Latent Tuberculosis Infection. Respiration 2021; 100:411-415. [PMID: 33706314 DOI: 10.1159/000514110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 12/29/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Asylum seekers in Switzerland have to register in federal asylum centres (FACs) before formal permission to enter the country. Some of them may have active tuberculosis (TB), exposing fellow refugees and employees. OBJECTIVES The aim of this study was to assess the risk of TB infection among employees of Swiss FACs. METHODS Between 2010 and 2018, a free interferon-gamma release assay (IGRA) was offered to all employees of 8 FACs, at employment and at yearly intervals. We defined latent TB infection as IGRA conversion from negative to positive. IGRA-positive employees were referred to a medical centre for further clinical follow-up. RESULTS 1,427 tests were performed among 737 employees (54.6% male). 403 (55%) persons were tested only once; 330 (44.5%) were tested several times; for 4 (0.5%) persons, the number of IGRA tests is unknown. Twenty employees (2.7%) had a positive IGRA at baseline, 2 (0.6%) converted from negative to positive during follow-up, resulting in an incidence of 22/10,000 person-years. We observed no case of active TB among employees. CONCLUSIONS The prevalence of latent TB among employees to Swiss FACs and the risk of acquiring TB infection through work-related exposure are low. Yearly IGRA controls in the absence of documented TB exposure seem unnecessary.
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Affiliation(s)
| | | | | | | | - Axel Jeremias Schmidt
- Infectious Diseases Division, Federal Office of Public Health FOPH, Bern, Switzerland
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18
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Allen AR, Ford T, Skuce RA. Does Mycobacterium tuberculosis var. bovis Survival in the Environment Confound Bovine Tuberculosis Control and Eradication? A Literature Review. Vet Med Int 2021; 2021:8812898. [PMID: 33628412 PMCID: PMC7880718 DOI: 10.1155/2021/8812898] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 01/12/2021] [Accepted: 01/25/2021] [Indexed: 12/13/2022] Open
Abstract
Bovine tuberculosis (bTB) is one of the globe's most common, multihost zoonoses and results in substantial socioeconomic costs for governments, farming industries, and tax payers. Despite decades of surveillance and research, surprisingly, little is known about the exact mechanisms of transmission. In particular, as a facultative intracellular pathogen, to what extent does survival of the causative agent, Mycobacterium tuberculosis var. bovis (M. bovis), in the environment constitute an epidemiological risk for livestock and wildlife? Due largely to the classical pathology of cattle cases, the received wisdom was that bTB was spread by direct inhalation and exchange of bioaerosols containing droplets laden with bacteria. Other members of the Mycobacterium tuberculosis complex (MTBC) exhibit differing host ranges, an apparent capacity to persist in environmental fomites, and they favour a range of different transmission routes. It is possible, therefore, that infection from environmental sources of M. bovis could be a disease transmission risk. Recent evidence from GPS-collared cattle and badgers in Britain and Ireland suggests that direct transmission by infectious droplets or aerosols may not be the main mechanism for interspecies transmission, raising the possibility of indirect transmission involving a contaminated, shared environment. The possibility that classical pulmonary TB can be simulated and recapitulated in laboratory animal models by ingestion of contaminated feed is a further intriguing indication of potential environmental risk. Livestock and wildlife are known to shed M. bovis onto pasture, soil, feedstuffs, water, and other fomites; field and laboratory studies have indicated that persistence is possible, but variable, under differing environmental conditions. Given the potential infection risk, it is timely to review the available evidence, experimental approaches, and methodologies that could be deployed to address this potential blind spot and control point. Although we focus on evidence from Western Europe, the concepts are widely applicable to other multihost bTB episystems.
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Affiliation(s)
- Adrian R. Allen
- Agri-Food and Biosciences Institute, Veterinary Sciences Division, Bacteriology Branch, Stoney Road Stormont, Belfast BT4 3SD, Northern Ireland, UK
| | - Tom Ford
- Agri-Food and Biosciences Institute, Veterinary Sciences Division, Bacteriology Branch, Stoney Road Stormont, Belfast BT4 3SD, Northern Ireland, UK
| | - Robin A. Skuce
- Agri-Food and Biosciences Institute, Veterinary Sciences Division, Bacteriology Branch, Stoney Road Stormont, Belfast BT4 3SD, Northern Ireland, UK
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19
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Lindsley WG, Blachere FM, Burton NC, Christensen B, Estill CF, Fisher EM, Martin SB, Mead KR, Noti JD, Seaton M. COVID-19 and the Workplace: Research Questions for the Aerosol Science Community. AEROSOL SCIENCE AND TECHNOLOGY : THE JOURNAL OF THE AMERICAN ASSOCIATION FOR AEROSOL RESEARCH 2020; 54:1117-1123. [PMID: 35924028 PMCID: PMC9345404 DOI: 10.1080/02786826.2020.1796921] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 07/14/2020] [Indexed: 06/13/2023]
Affiliation(s)
- William G. Lindsley
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - Francoise M. Blachere
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - Nancy C. Burton
- Division of Field Studies & Engineering, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, Ohio, USA
| | | | - Cherie F. Estill
- Division of Field Studies & Engineering, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, Ohio, USA
| | - Edward M. Fisher
- National Personal Protective Technology Laboratory, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Pittsburgh, Pennsylvania, USA
| | - Stephen B. Martin
- Respiratory Health Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - Kenneth R. Mead
- Division of Field Studies & Engineering, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, Ohio, USA
| | - John D. Noti
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - Melissa Seaton
- Division of Science Integration, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, Ohio, USA
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20
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Azimi P, Keshavarz Z, Cedeno Laurent JG, Allen JG. Estimating the nationwide transmission risk of measles in US schools and impacts of vaccination and supplemental infection control strategies. BMC Infect Dis 2020; 20:497. [PMID: 32652940 PMCID: PMC7351650 DOI: 10.1186/s12879-020-05200-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 06/25/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND The spread of airborne infectious diseases such as measles is a critical public health concern. The U.S. was certified measles-free in 2000, but the number of measles cases has increased in recent years breaking the record of the nationwide annual number of cases since 1992. Although the characteristics of schools have made them one of the most vulnerable environments during infection outbreaks, the transmission risk of measles among students is not completely understood. We aimed to evaluate how three factors influence measles transmission in schools: personal (vaccination), social (compartmentalizing), and building systems (ventilation, purification, and filtration). METHODS We used a combination of a newly developed multi-zone transient Wells-Riley approach, a nationwide representative School Building Archetype (SBA) model, and a Monte-Carlo simulation to estimate measles risk among U.S. students. We compared our risk results with the range of reported transmission rates of measles in school outbreaks to validate the risk model. We also investigated the effectiveness of vaccination and ten supplemental infection control scenarios for reducing the risk of measles transmission among students. RESULTS Our best nationwide estimate of measles transmission risk in U.S. schools were 3.5 and 32% among all (both unvaccinated and immunized) and unvaccinated students, respectively. The results showed the transmission risk of measles among unvaccinated students is > 70 times higher than properly immunized ones. We also demonstrated that the transmission risk of measles in primary schools (assuming teacher self-contained classrooms) is less than secondary schools (assuming departmentalized systems). For building-level interventions, schools with ductless-with-air-filter and ductless-without-air-filter systems have the lowest and highest transmission risks of measles, respectively. Finally, our simulation showed that infection control strategies could cut the average number of infected cases among all students in half when a combination of advanced air filtration, ventilation, and purification was adopted in the modeled schools. CONCLUSIONS Our results highlight the primary importance of vaccination for reducing the risk of measles transmission among students. Yet, additional and significant risk reduction can be achieved through compartmentalizing students and enhancing building ventilation and filtration systems.
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Affiliation(s)
- Parham Azimi
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, USA.
| | - Zahra Keshavarz
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, USA
| | | | - Joseph G Allen
- Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, USA
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21
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Fox GJ, Redwood L, Chang V, Ho J. The Effectiveness of Individual and Environmental Infection Control Measures in Reducing the Transmission of Mycobacterium tuberculosis: A Systematic Review. Clin Infect Dis 2020; 72:15-26. [DOI: 10.1093/cid/ciaa719] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 06/04/2020] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background
Transmission of Mycobacterium tuberculosis in healthcare settings is a preventable driver of the global tuberculosis epidemic. We aimed to assess the evidence for infection control interventions, including cough etiquette, engineering and personal respiratory protection measures, to prevent transmission of M. tuberculosis in healthcare settings.
Methods
Three independent systematic reviews were performed using 6 databases and clinical trials websites. Randomized trials, cohort studies, before-after studies, and case-control studies were included. Searches were performed for controlled studies evaluating respiratory hygiene, engineering, and personal respiratory protection measures. Outcome measures included the incidence of tuberculosis infection and disease. Studies involving transmission to either humans or animals were included.
Results
Evaluation of respiratory hygiene and cough etiquette interventions identified 4 human studies, with 22 855 participants, and 1 guinea pig study. Studies in humans evaluated the effects of multiple concurrent interventions. Patient use of surgical masks reduced infection by 14.8%, and tuberculosis disease was reduced by between 0.5% and 28.9%. Engineering and environmental interventions were evaluated in 10 studies of humans, including 31 776 human participants, and 2 guinea pig studies. Mechanical ventilation was associated with between 2.9% and 14% less infection. Nine studies of personal respiratory protection were included, including 33 913 participants. Infection was reduced by between 0% and 14.8% in studies where particulate respirators were used. The quality of included studies was assessed as low.
Conclusions
Respiratory hygiene, engineering, and environmental infection controls and personal respiratory protection interventions were associated with reduced transmission of M. tuberculosis and reduced tuberculosis disease in healthcare settings.
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Affiliation(s)
- Greg J Fox
- Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
- Woolcock Institute of Medical Research, Glebe, New South Wales, Australia
| | - Lisa Redwood
- Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Vicky Chang
- Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Jennifer Ho
- Woolcock Institute of Medical Research, Glebe, New South Wales, Australia
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22
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Nathavitharana RR, Lederer P, Tierney DB, Nardell E. Treatment as prevention and other interventions to reduce transmission of multidrug-resistant tuberculosis. Int J Tuberc Lung Dis 2020; 23:396-404. [PMID: 31064617 DOI: 10.5588/ijtld.18.0276] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Drug-resistant tuberculosis (DR-TB) represents a major programmatic challenge at the national and global levels. Only ∼30% of patients with multidrug-resistant TB (MDR-TB) were diagnosed, and ∼25% were initiated on treatment for MDR-TB in 2016. Increasing evidence now points towards primary transmission of DR-TB, rather than inadequate treatment, as the main driver of the DR-TB epidemic. The cornerstone of DR-TB transmission prevention should be earlier diagnosis and prompt initiation of effective treatment for all patients with DR-TB. Despite the extensive scale-up of Xpert® MTB/RIF testing, major implementation barriers continue to limit its impact. Although there is longstanding evidence in support of the rapid impact of treatment on patient infectiousness, delays in the initiation of effective DR-TB treatment persist, resulting in ongoing transmission. However, it is also imperative to address the burden of latent drug-resistant tuberculous infection because it is estimated that many DR-TB patients will become infectious before seeking care and encounter various diagnostic delays before treatment. Addressing latent DR-TB primarily consists of identifying, treating and following the contacts of patients with MDR-TB, typically through household contact evaluation. Adjunctive measures, such as improved ventilation and use of germicidal ultraviolet technology can further reduce TB transmission in high-risk congregate settings. Although many gaps remain in our biological understanding of TB transmission, implementation barriers to early diagnosis and rapid initiation of effective DR-TB treatment can and must be overcome if we are to impact DR-TB incidence in the short and long term.
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Affiliation(s)
- R R Nathavitharana
- Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - P Lederer
- Section of Infectious Diseases, Boston Medical Center, Boston, Massachusetts
| | - D B Tierney
- Division of Global Health Equity, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - E Nardell
- Division of Global Health Equity, Brigham and Women's Hospital, Boston, Massachusetts, USA
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23
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Emergency Department Design in Low- and Middle-Income Settings: Lessons from a University Hospital in Haiti. Ann Glob Health 2020; 86:6. [PMID: 31998609 PMCID: PMC6978988 DOI: 10.5334/aogh.2568] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Background: Studies from high-income settings have demonstrated that emergency department (ED) design is closely related to operational success; however, no standards exist for ED design in low- and middle-income countries (LMICs). Objective: We present ED design recommendations for LMICs based on our experience designing and operating the ED at Hôpital Universitaire de Mirebalais (HUM), an academic hospital in central Haiti. We also propose an ideal prototype for similar settings based on these recommendations. Methods: As part of a quality improvement project to redesign the HUM ED, we collected feedback on the current design from key stakeholders to identify design features impacting quality and efficiency of care. Feedback was reviewed by the clinical and design teams and consensus reached on key lessons learned, from which the prototype was designed. Findings and conclusions: ED design in LMICs must balance construction costs, sustainability in the local context, and the impact of physical infrastructure on care delivery. From our analysis, we propose seven key recommendations: 1) Design the “front end” of the ED with waiting areas that meet the needs of LMICs and dedicated space for triage to strengthen care delivery and patient safety. 2) Determine ED size and bed capacity with an understanding of the local health system and disease burden, and ensure line-of-sight visibility for ill patients, given limited monitoring equipment. 3) Accommodate for limited supply chains by building storage spaces that can manage large volumes of supplies. 4) Prioritize a maintainable system that can provide reliable oxygen. 5) Ensure infection prevention and control, including isolation rooms, by utilizing simple and affordable ventilation systems. 6) Give consideration to security, privacy, and well-being of patients, families, and staff. 7) Site the ED strategically within the hospital. Our prototype incorporates these features and may serve as a model for other EDs in LMICs.
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24
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Nunayon SS, Zhang H, Lai ACK. Comparison of disinfection performance of UVC-LED and conventional upper-room UVGI systems. INDOOR AIR 2020; 30:180-191. [PMID: 31688980 DOI: 10.1111/ina.12619] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 11/02/2019] [Accepted: 11/04/2019] [Indexed: 05/05/2023]
Abstract
We developed a novel, compact upper-room ultraviolet germicidal irradiation system with light-emitting diode sources (UR-UVGI-LED) to enhance the disinfection of bioaerosols in an enclosed room space. Its effectiveness was evaluated and compared with the conventional upper-room ultraviolet germicidal irradiation system with mercury vapor sources (UR-UVGI-MV). Escherichia coli, Serratia marcescens, and Staphylococcus epidermidis were atomized under the well-mixed condition and exposed to UR-UVGI-LED (or UR-UVGI-MV) device. The intensity output of the UR-UVGI-LED was also varied from 0% (no LED), 25%, 50% to 100% to further evaluate the UR-UVGI-LED disinfection effectiveness under different power levels. The decay rates for UR-UVGI-LED ranged from -0.1420 ± 0.04 min-1 to -0.3331 ± 0.07 min-1 for Escherichia coli, -0.1288 ± 0.01 min-1 to -0.3583 ± 0.02 min-1 for Serratia marcescens, and -0.0330 ± 0.01 min-1 to -0.0487 ± 0.01 min-1 for Staphylococcus epidermidis. It was noticed that the intensity level had a non-linear influence on the UR-UVGI-LED's performance. The decay rates achieved by the UR-UVGI-MV system were -0.3867 ± 0.08 min-1 , -0.4745 ± 0.002 min-1 , and -0.1624 ± 0.02 min-1 for Escherichia coli, Serratia marcescens, and Staphylococcus epidermidis, respectively. Hence, the disinfection performance of both UR-UVGI-LED and UR-UVGI-MV systems was comparable for Escherichia coli and Serratia marcescens. These results demonstrate that the UR-UVGI-LED system has a high potential to be used as a safe and effective irradiated light source to disinfect indoor airborne pathogens.
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Affiliation(s)
- Sunday S Nunayon
- Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China
| | - Huihui Zhang
- Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China
| | - Alvin C K Lai
- Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China
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25
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Migliori GB, Nardell E, Yedilbayev A, D'Ambrosio L, Centis R, Tadolini M, van den Boom M, Ehsani S, Sotgiu G, Dara M. Reducing tuberculosis transmission: a consensus document from the World Health Organization Regional Office for Europe. Eur Respir J 2019; 53:13993003.00391-2019. [PMID: 31023852 DOI: 10.1183/13993003.00391-2019] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 03/18/2019] [Indexed: 12/11/2022]
Abstract
Evidence-based guidance is needed on 1) how tuberculosis (TB) infectiousness evolves in response to effective treatment and 2) how the TB infection risk can be minimised to help countries to implement community-based, outpatient-based care.This document aims to 1) review the available evidence on how quickly TB infectiousness responds to effective treatment (and which factors can lower or boost infectiousness), 2) review policy options on the infectiousness of TB patients relevant to the World Health Organization European Region, 3) define limitations of the available evidence and 4) provide recommendations for further research.The consensus document aims to target all professionals dealing with TB (e.g TB specialists, pulmonologists, infectious disease specialists, primary healthcare professionals, and other clinical and public health professionals), as well as health staff working in settings where TB infection is prevalent.
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Affiliation(s)
- Giovanni Battista Migliori
- Respiratory Diseases Clinical Epidemiology Unit, Clinical Scientific Institutes Maugeri, IRCCS, Tradate, Italy.,These authors contributed equally to this work
| | - Edward Nardell
- Division of Global Health Equity, Harvard Medical School, Brigham and Women's Hospital, Boston, MA, USA.,These authors contributed equally to this work
| | | | | | - Rosella Centis
- Respiratory Diseases Clinical Epidemiology Unit, Clinical Scientific Institutes Maugeri, IRCCS, Tradate, Italy
| | - Marina Tadolini
- Dept of Medical and Surgical Sciences, Alma Mater Studiorum University of Bologna, Bologna, Italy
| | - Martin van den Boom
- Joint Tuberculosis, HIV and Viral Hepatitis Programme, WHO Regional Office for Europe, Copenhagen, Denmark.,These authors contributed equally to this work
| | - Soudeh Ehsani
- Joint Tuberculosis, HIV and Viral Hepatitis Programme, WHO Regional Office for Europe, Copenhagen, Denmark
| | - Giovanni Sotgiu
- Clinical Epidemiology and Medical Statistics Unit, Dept of Medical, Surgical and Experimental Sciences, University of Sassari, Sassari, Italy.,These authors contributed equally to this work
| | - Masoud Dara
- Joint Tuberculosis, HIV and Viral Hepatitis Programme, WHO Regional Office for Europe, Copenhagen, Denmark
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26
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Chen YC, Liao CH, Shen WT, Su C, Wu YC, Tsai MH, Hsiao SS, Yu KP, Tseng CH. Effective disinfection of airborne microbial contamination in hospital wards using a zero-valent nano-silver/TiO 2 -chitosan composite. INDOOR AIR 2019; 29:439-449. [PMID: 30738001 DOI: 10.1111/ina.12543] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 02/04/2019] [Accepted: 02/05/2019] [Indexed: 06/09/2023]
Abstract
A novel antimicrobial composite of zero-valent silver nanoparticles (AgNPs), titania (TiO2 ), and chitosan (CS) was prepared via photochemical deposition of AgNPs on a CS-TiO2 matrix (AgNPs@CS-TiO2 ). Electron microscopy showed that the AgNPs were well dispersed on the CS-TiO2 , with diameters of 6.69-8.84 nm. X-ray photoelectron spectra indicated that most of the AgNPs were reduced to metallic Ag. Fourier-transform infrared spectroscopy indicated that some AgNPs formed a chelate with CS through coordination of Ag+ with the CS amide II groups. The zones of inhibition of AgNPs@CS-TiO2 for bacteria (Escherichia coli and Staphylococcus epidermidis) and fungi (Aspergillus niger and Penicillium spinulosum) were 6.72-11.08 and 5.45-5.77 mm, respectively, and the minimum (critical) concentrations of AgNPs required to inhibit the growth of bacteria and fungi were 7.57 and 16.51 µg-Ag/mm2 , respectively. The removal efficiency of a AgNPs@TiO2 -CS bed filter for bioaerosols (η) increased with the packing depth, and the optimal filter quality (qF) occurred for packing depths of 2-4 cm (qF = 0.0285-0.103 Pa-1 ; η = 57.6%-98.2%). When AgNPs@TiO2 -CS bed filters were installed in the ventilation systems of hospital wards, up to 88% of bacteria and 97% of fungi were removed within 30 minutes. Consequently, AgNPs@TiO2 -CS has promising potentials in bioaerosol purification.
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Affiliation(s)
- Yen-Chi Chen
- Institute of Environmental and Occupational Health Sciences, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Chun-Hsing Liao
- Department of Internal Medicine, Far-Eastern Memosrial Hospital, New Taipei City, Taiwan, ROC
- Department of Medicine, National Yang-Ming University, Taiwan, ROC
| | - Wan-Tien Shen
- Institute of Environmental and Occupational Health Sciences, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Chien Su
- Institute of Environmental and Occupational Health Sciences, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Yu-Chiao Wu
- Institute of Environmental and Occupational Health Sciences, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Ming-Hsuan Tsai
- Institute of Environmental and Occupational Health Sciences, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Shui-Shu Hsiao
- Office of Medical Engineering, Far-Eastern Memorial Hospital, New Taipei City, Taiwan, ROC
| | - Kuo-Pin Yu
- Institute of Environmental and Occupational Health Sciences, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Chao-Heng Tseng
- Institute of Environmental Engineering and Management, National Taipei University of Technology, Taipei, Taiwan, ROC
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Indoor air quality in health care facilities: a call for a concerted multidisciplinary effort. ASIAN BIOMED 2019. [DOI: 10.1515/abm-2019-0001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Küsel RR, Craig IK, Stoltz AC. Modeling the Airborne Infection Risk of Tuberculosis for a Research Facility in eMalahleni, South Africa. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2019; 39:630-646. [PMID: 30229975 DOI: 10.1111/risa.13180] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 06/30/2017] [Accepted: 07/03/2018] [Indexed: 06/08/2023]
Abstract
A detailed mathematical modeling framework for the risk of airborne infectious disease transmission in indoor spaces was developed to enable mathematical analysis of experiments conducted at the Airborne Infections Research (AIR) facility, eMalahleni, South Africa. A model was built using this framework to explore possible causes of why an experiment at the AIR facility did not produce expected results. The experiment was conducted at the AIR facility from August 31, 2015 to December 4, 2015, in which the efficacy of upper room germicidal ultraviolet (GUV) irradiation as an environmental control was tested. However, the experiment did not produce the expected outcome of having fewer infections in the test animal room than the control room. The simulation results indicate that dynamic effects, caused by switching the GUV lights, power outages, or introduction of new patients, did not result in the unexpected outcomes. However, a sensitivity analysis highlights that significant uncertainty exists with risk of transmission predictions based on current measurement practices, due to the reliance on large viable literature ranges for parameters.
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Affiliation(s)
- Ralf R Küsel
- Department of Electrical, Electronic and Computer Engineering, University of Pretoria, Pretoria, South Africa
| | - Ian K Craig
- Department of Electrical, Electronic and Computer Engineering, University of Pretoria, Pretoria, South Africa
| | - Anton C Stoltz
- Department of Internal Medicine, University of Pretoria, Pretoria, South Africa
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Jin Y, Wang H, Zhang J, Ding C, Wen K, Fan J, Li T. Prevalence of latent tuberculosis infection among coal workers' pneumoconiosis patients in China: a cross-sectional study. BMC Public Health 2018; 18:473. [PMID: 29642880 PMCID: PMC5896101 DOI: 10.1186/s12889-018-5373-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 03/26/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Little is known about the prevalence of latent tuberculosis infection (LTBI) among coal workers' pneumoconiosis (CWP) patients. To estimate the prevalence of LTBI and identify its associated risk factors among CWP patients. METHODS A cross-sectional study was conducted to assess the prevalence of LTBI. Participants were screened for active TB or a history of TB by X-ray and those that underwent QuantiFERON-TB Gold In-Tube (QFT) test. A standardized questionnaire was completed and risk factors were assessed for acquiring TB. Log-binomial regression was used to estimate the LTBI prevalence ratio (PR) in relation to risk factors. RESULTS Of 244 individuals with CWP (median age 67 years; all male), 162 (66.4%) were QFT positive. In Multivariate analysis, poor workplace ventilation (adjusted prevalence ratio [APR] = 1.26) and intake of fruits regularly (≥4 days of every week) (APR = 0.81) (all p < 0.05) were associated with a decreased risk of QFT. CONCLUSIONS This study showed a high prevalence of LTBI among individuals with CWP in China. Poor workplace ventilation may be an important contributing factor for LTBI. Regular monitoring and dust control measures need to be improved in workplaces to ensure the safety of workers. Moreover, intake of fruits regularly may be a protective factor for LTBI. However, the effect of fruits should be further studied.
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Affiliation(s)
- Yan Jin
- National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, China
- Department of Infectious Disease, Taizhou Center for Disease Control and Prevention, Taizhou, China
| | - Huanqiang Wang
- National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jianfang Zhang
- Research Center for Occupational Safety and Health, State Administration of Work Safety, Beijing, China
| | - Chunguang Ding
- Research Center for Occupational Safety and Health, State Administration of Work Safety, Beijing, China
| | - Ke Wen
- National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jingguang Fan
- Research Center for Occupational Safety and Health, State Administration of Work Safety, Beijing, China
| | - Tao Li
- National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, China
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Abstract
The DOTS strategy assisted global tuberculosis (TB) control, but was unable to prevent the emergence and spread of drug-resistant strains. Genomic evidence confirms the transmission of drug-resistant Mycobacterium tuberculosis strains in many different settings, indicative of epidemic spread. These findings emphasise the need for enhanced infection control measures in health care and congregate settings. Young children in TB endemic areas are particularly vulnerable. Although advances in TB drug and vaccine development are urgently needed, improved access to currently available preventive therapy and treatment for drug resistant TB could reduce the disease burden and adverse outcomes experienced by children. We review new insights into the transmission dynamics of drug resistant TB, the estimated disease burden in children and optimal management strategies to consider.
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Affiliation(s)
- Alexander C Outhred
- The Children's Hospital at Westmead and the Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, Australia
| | - Philip N Britton
- The Children's Hospital at Westmead and the Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, Australia
| | - Ben J Marais
- The Children's Hospital at Westmead and the Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, Australia.
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Flick RJ, Munthali A, Simon K, Hosseinipour M, Kim MH, Mlauzi L, Kazembe PN, Ahmed S. Assessing infection control practices to protect health care workers and patients in Malawi from nosocomial transmission of Mycobacterium tuberculosis. PLoS One 2017; 12:e0189140. [PMID: 29211793 PMCID: PMC5718482 DOI: 10.1371/journal.pone.0189140] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Accepted: 11/20/2017] [Indexed: 01/21/2023] Open
Abstract
Transmission of Mycobacterium tuberculosis (TB) in health settings threatens health care workers and people living with HIV in sub-Saharan Africa. Nosocomial transmission is reduced with implementation of infection control (IC) guidelines. The objective of this study is to describe implementation of TB IC measures in Malawi. We conducted a cross-sectional study utilizing anonymous health worker questionnaires, semi-structured interviews with facility managers, and direct observations at 17 facilities in central Malawi. Of 592 health care workers surveyed, 34% reported that all patients entering the facility were screened for cough and only 8% correctly named the four most common signs and symptoms of TB in adults. Of 33 managers interviewed, 7 (21%) and 1 (3%) provided the correct TB screening questions for use in adults and children, respectively. Of 592 health workers, only 2.4% had been screened for TB in the previous year. Most (90%) reported knowing their HIV status, 53% were tested at their facility of employment, and half reported they would feel comfortable receiving ART or TB treatment at their facility of employment. We conclude that screening is infrequently conducted and knowledge gaps may undercut its effectiveness. Further, health care workers do not routinely access TB and HIV diagnostic and treatment services at their facility of employment.
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Affiliation(s)
- Robert J. Flick
- Baylor College of Medicine Children’s Foundation Malawi, Lilongwe, Malawi
- University of North Carolina Project-Malawi, Lilongwe, Malawi
- University of Colorado School of Medicine, Denver, United States of America
| | - Adamson Munthali
- Baylor College of Medicine Children’s Foundation Malawi, Lilongwe, Malawi
| | - Katherine Simon
- Baylor College of Medicine Children’s Foundation Malawi, Lilongwe, Malawi
- Baylor International Pediatric AIDS Initiative at Texas Children’s Hospital, Baylor College of Medicine, Houston, United States of America
| | - Mina Hosseinipour
- University of North Carolina Project-Malawi, Lilongwe, Malawi
- University of North Carolina at Chapel Hill, Chapel Hill, United States of America
| | - Maria H. Kim
- Baylor College of Medicine Children’s Foundation Malawi, Lilongwe, Malawi
- Baylor International Pediatric AIDS Initiative at Texas Children’s Hospital, Baylor College of Medicine, Houston, United States of America
| | - Lameck Mlauzi
- Malawi Ministry of Health National Tuberculosis Control Programme, Lilongwe, Malawi
| | - Peter N. Kazembe
- Baylor College of Medicine Children’s Foundation Malawi, Lilongwe, Malawi
- Baylor International Pediatric AIDS Initiative at Texas Children’s Hospital, Baylor College of Medicine, Houston, United States of America
| | - Saeed Ahmed
- Baylor College of Medicine Children’s Foundation Malawi, Lilongwe, Malawi
- Baylor International Pediatric AIDS Initiative at Texas Children’s Hospital, Baylor College of Medicine, Houston, United States of America
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Yan Y, Li X, Shang Y, Tu J. Evaluation of airborne disease infection risks in an airliner cabin using the Lagrangian-based Wells-Riley approach. BUILDING AND ENVIRONMENT 2017; 121:79-92. [PMID: 32287972 PMCID: PMC7111330 DOI: 10.1016/j.buildenv.2017.05.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 04/28/2017] [Accepted: 05/08/2017] [Indexed: 05/03/2023]
Abstract
An urgent demand of assessing passengers' exposure risks in airliner cabins was raised as commercial airliners are one of the major media that carrying and transmitting infectious disease worldwide. In this study, simulations were conducted using a Boeing 737 cabin model to study the transport characteristics of airborne droplets and the associated infection risks of passengers. The numerical results of the airflow field were firstly compared against the experimental data in the literature to validate the reliability of the simulations. Airborne droplets were assumed to be released by passengers through coughing and their transport characteristics were modelled using the Lagrangian approach. Numerical results found that the particle travel distance was very sensitive to the release locations, and the impact was more significant along the longitudinal and horizontal directions. Particles released by passengers sitting next to the windows could travel much further than the others. A quantifiable approach was then applied to assess the individual infection risks of passengers. The key particle transport information such as the particle residence time yielded from the Lagrangian tracking process was extracted and integrated into the Wells-Riley equation to estimate the risks of infection. Compared to the Eulerian-based approach, the Lagrangian-based approach presented in this study is more robust as it addresses both the particle concentration and particle residence time in the breathing zone of every individual passenger.
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Affiliation(s)
- Yihuan Yan
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia
| | - Xiangdong Li
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia
| | - Yidan Shang
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia
| | - Jiyuan Tu
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083, Australia
- Key Laboratory of Ministry of Education for Advanced Reactor Engineering and Safety, Institute of Nuclear and New Energy Technology, Tsinghua University, PO Box 1021, Beijing 100086, China
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Hospital Environments and Epidemiology of Healthcare-Associated Infections. SPRINGERBRIEFS IN PUBLIC HEALTH 2017. [PMCID: PMC7120574 DOI: 10.1007/978-3-319-49160-8_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
Today, hospitals are facing difficult challenges: increasing proportion of immunologically vulnerable patients often affected by diseases requiring high complex level of healthcare; rapidly evolving medical technologies and healthcare models; and budget restrictions. All these features interfere with healthcare and can modify the risk of acquiring healthcare-associated infections (HCAIs). Therefore, HCAI prevention is a high priority for healthcare systems. Authors describe human and environmental origin of HCAIs, focusing on the modality of transmission of those airborne pathogens, including the new insight derived from the recent acquisitions about SARS and Ebola epidemiology. They also describe the state of the art about microorganism concentration (infective dose) required to determine a HCAI and the role played by other virulence factors. Finally, the effective control measures used for the prevention of airborne pathogen transmission are described, focusing mainly on the risk assessment and infection control.
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Duchaine C. Assessing microbial decontamination of indoor air with particular focus on human pathogenic viruses. Am J Infect Control 2016; 44:S121-6. [PMID: 27590696 PMCID: PMC7115274 DOI: 10.1016/j.ajic.2016.06.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 06/03/2016] [Indexed: 11/21/2022]
Abstract
Transmission of bacterial, fungal, and viral pathogens is of primary importance in public and occupational health and infection control. Although several standardized protocols have been proposed to target microbes on fomites through surface decontamination, use of microbicidal agents, and cleaning processes, only limited guidance is available on microbial decontamination of indoor air to reduce the risk of pathogen transmission between individuals. This article reviews the salient aspects of airborne transmission of infectious agents, exposure assessment, in vitro assessment of microbicidal agents, and processes for air decontamination for infection prevention and control. Laboratory-scale testing (eg, rotating chambers, wind tunnels) and promising field-scale methodologies to decontaminate indoor air are also presented. The potential of bacteriophages as potential surrogates for the study of airborne human pathogenic viruses is also discussed.
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Affiliation(s)
- Caroline Duchaine
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec City, QC, Canada.
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36
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Nasir ZA, Campos LC, Christie N, Colbeck I. Airborne biological hazards and urban transport infrastructure: current challenges and future directions. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:15757-66. [PMID: 27318484 PMCID: PMC4956722 DOI: 10.1007/s11356-016-7064-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/08/2016] [Indexed: 05/05/2023]
Abstract
Exposure to airborne biological hazards in an ever expanding urban transport infrastructure and highly diverse mobile population is of growing concern, in terms of both public health and biosecurity. The existing policies and practices on design, construction and operation of these infrastructures may have severe implications for airborne disease transmission, particularly, in the event of a pandemic or intentional release of biological of agents. This paper reviews existing knowledge on airborne disease transmission in different modes of transport, highlights the factors enhancing the vulnerability of transport infrastructures to airborne disease transmission, discusses the potential protection measures and identifies the research gaps in order to build a bioresilient transport infrastructure. The unification of security and public health research, inclusion of public health security concepts at the design and planning phase, and a holistic system approach involving all the stakeholders over the life cycle of transport infrastructure hold the key to mitigate the challenges posed by biological hazards in the twenty-first century transport infrastructure.
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Affiliation(s)
- Zaheer Ahmad Nasir
- School of Energy, Environment and Agrifood, Cranfield University, Cranfield, Bedfordshire, MK43 0AL, UK.
| | - Luiza Cintra Campos
- Department of Civil, Environmental and Geomatic Engineering, University College London, London, WC1E 6BT, UK
| | - Nicola Christie
- Department of Civil, Environmental and Geomatic Engineering, University College London, London, WC1E 6BT, UK
| | - Ian Colbeck
- School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK
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Richardson ET, Morrow CD, Ho T, Fürst N, Cohelia R, Tram KH, Farmer PE, Wood R. Forced removals embodied as tuberculosis. Soc Sci Med 2016; 161:13-8. [PMID: 27239703 DOI: 10.1016/j.socscimed.2016.05.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 05/04/2016] [Accepted: 05/08/2016] [Indexed: 11/19/2022]
Abstract
South Africa has one of the worst tuberculosis burdens in the world. Several ecological forces have contributed to this, including high HIV prevalence; failing TB control strategies; crowded, poorly ventilated indoor environments-including the complex web of political and economic interests which produce them; the development of racial capitalism; and mining and migration. In the following study, we measure CO2 levels in public transport to investigate the role extended commutes from peri-urban settlements to urban sites of work-a direct result of forced removals-potentially play in propagating the TB epidemic in Cape Town, South Africa.
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Affiliation(s)
- Eugene T Richardson
- Department of Anthropology, Stanford University, Stanford, USA; Division of Global Health Equity, Brigham and Women's Hospital, Boston, USA; Desmond Tutu HIV Centre, University of Cape Town, South Africa.
| | - Carl D Morrow
- Desmond Tutu HIV Centre, University of Cape Town, South Africa
| | - Theodore Ho
- Desmond Tutu HIV Centre, University of Cape Town, South Africa
| | - Nicole Fürst
- Desmond Tutu HIV Centre, University of Cape Town, South Africa
| | | | - Khai Hoan Tram
- Desmond Tutu HIV Centre, University of Cape Town, South Africa
| | - Paul E Farmer
- Division of Global Health Equity, Brigham and Women's Hospital, Boston, USA; Department of Global Health and Social Medicine, Harvard Medical School, Boston, USA
| | - Robin Wood
- Desmond Tutu HIV Centre, University of Cape Town, South Africa
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