Spread Of Airborne Infectious Diseases Research Articles

Intelligent anti-infection ventilation strategy based on computer audition: Towards healthy built environment and low carbon emission

Airborne infectious diseases have had a significant negative influence on human health, well-being and socioeconomic development. Anti-infection ventilation is a critical tool for effectively preventing the spread of airborne infectious diseases. Infectious particulate matter concentration is the most direct factor affecting the effectiveness of anti-infection ventilation. Generally coughing and sneezing are typical transient behaviors of occupants that release large amounts of infectious particulate matter. However, there is a lack of unsteady-state models for predicting the effect of sneezing and coughing on infection risk, and have not been considered in conjunction with intelligent anti-infection ventilation. In this study, computer audition was coupled with a behavior-based unsteady-state prediction model to propose an intelligent anti-infection ventilation strategy. According to the results, increasing the ventilation rate within 10 min after coughing or sneezing, was the most effective in minimizing the infection transmission. Taking a real case as an example, when coughing and sneezing occurred and after 1 h of exposure, the proposed strategy could control the infection risk to 6.9% with an energy saving rate of 53.47% (0.24 kg of carbon emission reduction per hour). In summary, this study can help balance the relationship between energy consumption and infection risk and provide some references for comprehensive intelligent control of anti-infection ventilation.

Reducing the risk of viral contamination during the coronavirus pandemic by using a protective curtain in the operating room

BackgroundAirborne transmission diseases can transfer long and short distances via sneezing, coughing, and breathing. These airborne repertory particles can convert to aerosol particles and travel with airflow. During the Coronavirus disease 2019 (COVID-19) pandemic, many surgeries have been delayed, increasing the demand for establishing a clean environment for both patient and surgical team in the operating room.MethodsThis study aims to investigate the hypothesis of implementing a protective curtain to reduce the transmission of infectious contamination in the surgical microenvironment of an operating room. In this regard, the spread of an airborne transmission disease from the patient was evaluated, consequently, the exposure level of the surgical team. In the first part of this study, a mock surgical experiment was established in the operating room of an academic medical center in Norway. In the second part, the computational fluid dynamic technique was performed to investigate the spread of airborne infectious diseases. Furthermore, the field measurement was used to validate the numerical model and guarantee the accuracy of the applied numerical models.ResultsThe results showed that the airborne infectious agents reached the breathing zone of the surgeons. However, using a protective curtain to separate the microenvironment between the head and lower body of the patient resulted in a 75% reduction in the spread of the virus to the breathing zone of the surgeons. The experimental results showed a surface temperature of 40 ˚C, which was about a 20 ˚C increase in temperature, at the wound area using a high intensity of the LED surgical lamps. Consequently, this temperature increase can raise the patient's thermal injury risk.ConclusionThe novel method of using a protective curtain can increase the safety of the surgical team during the surgery with a COVID-19 patient in the operating room.

Impact of design parameters of diffuse ceiling ventilation systems on indoor air quality in school classrooms: a numerical assessment

Indoor air quality directly impacts an individual’s productivity and health condition in office buildings, hospitals, schools, and residential buildings. Diffuse ceiling systems have been used widely in classrooms at schools that have high heat loads. In this regard, this study investigated the role of diffuse ceiling design parameters, including active diffuse panels’ configuration and contamination locations, on indoor air quality in a classroom. The spread of airborne infectious diseases was simulated using computational fluid dynamics techniques. The results revealed that the central configuration of diffuse ceiling panels had the minimum spread of contaminations in the classroom compared to the dispersed configuration.

Reducing Effects of Anti-Epidemic (Quarantine) Measures during the COVID-19 Pandemic on the Incidence and Spread of Airborne Infectious Diseases (Based on the Example of Varicella)

Background. The coronavirus pandemic, also known as the COVID-19 pandemic, introduced significant changes in vital activities of the population and spread of airborne infectious diseases, the study of which enables ranking of preventive measures. The objective of our study was to assess the degree of influence of the lockdown and social distancing imposed in the Krasnodar Krai in 2020 due to the pandemic on the incidence of airborne communicable diseases based on the example of varicella. Materials and methods. We conducted a retrospective analysis of a 10-year incidence of varicella in the population of the Tuapse district, Krasnodar Krai using monthly and annual data on the incidence of infectious and parasitic diseases (Form No. 2) in the Tuapse district for 2011–2020 and the “Population Incidence” software, version 5, by applying standard techniques and methods of studying the epidemic process. Results. Stringent restrictive measures taken in the country in 2020 in the context of the COVID-19 pandemic caused a significant decrease (by 741 %) in the incidence of chickenpox among the population of the Tuapse district compared to the long-term average rate. In April – May and July – September 2020, varicella incidence rates were 30.98 and 7.75 per 100 thousand population or 7.4 and 18.8 times lower than the long-term average, respectively. The majority of chickenpox cases in the Tuapse district (as in the country as a whole) were pediatric – 94.02 % (RF – 94.3 %), with children aged 3 to 6 years making up 61 % of the total. Conclusion. The lockdown and social distancing imposed during the COVID-19 pandemic has a significant reducing effect on the incidence of airborne infectious diseases in the population in the absence of effective vaccination.

Effectiveness modelling of digital contact-tracing solutions for tackling the COVID-19 pandemic

AbstractSince the beginning of the coronavirus (COVID-19) global pandemic, digital contact-tracing applications (apps) have been at the centre of attention as a digital tool to enable citizens to monitor their social distancing, which appears to be one of the leading practices for mitigating the spread of airborne infectious diseases. Many countries have been working towards developing suitable digital contact-tracing apps to allow the measurement of the physical distance between citizens and to alert them when contact with an infected individual has occurred. However, the adoption of digital contact-tracing apps has faced several challenges so far, including interoperability between mobile devices and users’ privacy concerns. There is a need to reach a trade-off between the achievable technical performance of new technology, false-positive rates, and social and behavioural factors. This paper reviews a wide range of factors and classifies them into three categories of technical, epidemiological and social ones, and incorporates these into a compact mathematical model. The paper evaluates the effectiveness of digital contact-tracing apps based on received signal strength measurements. The results highlight the limitations, potential and challenges of the adoption of digital contact-tracing apps.

Inferring high-resolution human mixing patterns for disease modeling

Mathematical and computational modeling approaches are increasingly used as quantitative tools in the analysis and forecasting of infectious disease epidemics. The growing need for realism in addressing complex public health questions is, however, calling for accurate models of the human contact patterns that govern the disease transmission processes. Here we present a data-driven approach to generate effective population-level contact matrices by using highly detailed macro (census) and micro (survey) data on key socio-demographic features. We produce age-stratified contact matrices for 35 countries, including 277 sub-national administratvie regions of 8 of those countries, covering approximately 3.5 billion people and reflecting the high degree of cultural and societal diversity of the focus countries. We use the derived contact matrices to model the spread of airborne infectious diseases and show that sub-national heterogeneities in human mixing patterns have a marked impact on epidemic indicators such as the reproduction number and overall attack rate of epidemics of the same etiology. The contact patterns derived here are made publicly available as a modeling tool to study the impact of socio-economic differences and demographic heterogeneities across populations on the epidemiology of infectious diseases.

Cloth Face Coverings for Use as Facemasks During the Coronavirus (SARS-CoV-2) Pandemic: What Science and Experience Have Taught Us.

The current coronavirus (severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2]) pandemic has resulted in severe shortages of personal protective equipment, including respiratory protective equipment, such as N95 respirators. This has led some government agencies to suggest the use of cloth face coverings (CFCs) by health-care providers and the general public as a last resort when standard respiratory protective equipment is unavailable. Although such coverings have been in use for over a century and have found widespread use during some previous pandemics, research data are relatively scant for the protective value of this measure. This article, a literature review, explores the development of CFCs and reviews available scientific research regarding the efficacy of this intervention as a preventive measure in the spread of airborne infectious diseases.

Natural ventilation as a means of airborne tuberculosis infection control in minibus taxis

Airborne infection control measures are used extensively in health-care settings to curtail the spread of airborne infectious diseases. Few such measures are applied in public congregate spaces outside health facilities, such as those associated with public transport. In minibus taxis – a popular form of public transport in South Africa – poor ventilation creates conditions that allow for transmission of airborne diseases, particularly tuberculosis. In this study, we focused on developing quantitative ventilation profiles for the 16-seater Toyota Quantum Ses’fikile model commonly used in the Cape Town metropole. We studied the ventilation rates achievable in an occupied taxi under varying operational conditions, such as driving speed and open window configurations, which were based on observations made during preliminary taxi journeys. Two open-window configurations were found to provide ventilation rates close to or exceeding WHO recommended per-person requirements for high-risk clinical areas and are therefore likely to be effective in reducing the risk of tuberculosis transmission.
 Significance:
 
 The results obtained augment the limited data available on the role that natural ventilation can play in reducing TB transmission in minibus taxis.
 Ventilation rates were shown to depend on both the taxi speed and specific open window configuration, countering the notion that simply opening a random selection of windows provides adequate reduction in the transmission risk.

Laboratory Validation and Initial Field Testing of an Unobtrusive Bioaerosol Detector for Health Care Settings

ABSTRACT Microorganisms can be transmitted from infected to healthy people as an aerosol. Military bioaerosol detectors currently used by soldiers or first responders may potentially be utilized in health care settings as part of a strategy to prevent the spread of airborne infectious diseases. The goal of this study was to conduct initial laboratory and field validation of an inexpensive and unobtrusive TACBIO detector and compare its performance with that of an expensive bioaerosol detection instrument, the Ultraviolet Aerodynamic Particle Sizer (UV-APS). The laboratory validation test used three bacterial clusters (Bacillus thuringiensis [Bt], Bacillus anthracis Sterne [BaS], and Bacillus atrophaeus var. globigii [Bg]) generated at controlled rates by an ink jet aerosol generator (IJAG). The detection efficiency of the UV-APS was ≥ 99% for all particle generation rates and species. The TACBIO detector exhibited a slightly lower detection efficiency but was still able to detect > 88% of Bt and BaS and 62.7–81.7% of Bg. Field validation conducted with simultaneous UV-APS and TACBIO sampling in an occupied hospital clinic showed both instruments closely tracking each other in detecting fluorescent particles > 1.5 µm in diameter. During a 6 hour sampling period, fluorescent particle (> 1.5 µm) concentrations showed wide short term variation connected to nearby human activity while smaller nonfluorescent particles displayed more gradual changes. These results indicate the usefulness of an unobtrusive environmental aerosol sampler in health care settings, motivating future field characterization and validation studies.

A systematic approach to assessing indoor air quality of long term care facilities

Not much is known about the favourable indoor air quality in long term care facilities (LTCFs), where older adults suffering from dementia live. Older adults, especially those who suffer from dementia, are more sensible to the indoor environment. However, no special requirements for the indoor air in long term care facilities exist. Due to the decrease in cognition function, it is hard to evaluate comfort and health in this group. Nevertheless, infectious diseases are a persistent problem. Based on literature an assessment methodology has been developed to analyse LTCFs to determine if differences in building characteristics and Heating, Ventilation and Air Conditioning (HVAC) systems influence the spread of airborne infectious diseases. The developed methodology is applied in seven long term care facilities in the Netherlands. After that, the methodology has been evaluated and its feasibility and applicability are discussed. From this study, it can be concluded that this method has potential to evaluate, compare LTCFs, and develop design guidelines for these buildings. However, some adjustments to the methodology are necessary to achieve this objective. Therefore, the relation between the indoor environment and infection risk is not yet analysed, but a consistent procedure to analyse this link is provided.

A design for a more efficient, upper room germicidal ultraviolet air disinfection luminaire

This paper describes a novel optical design principle for an upper room germicidal ultraviolet luminaire developed to limit the transmission of airborne diseases, particularly tuberculosis. A prototype was built to demonstrate the principle, and tests were conducted to determine its total ultraviolet (UV)-C output, biological effectiveness, and safety for lower room occupants. The prototype outperformed frequently used luminaires in total UV-C output, luminaire efficiency, and biological effectiveness against aerosolised Mycobacterium, while remaining safe for lower room occupants. The results presented here suggest that the design principle is ready for real-world application to mitigate the spread of airborne infectious diseases.

A qualitative exploration of social contact patterns relevant to airborne infectious diseases in northwest Bangladesh.

In South Asia, the burden of infectious diseases is high. Socioeconomically and culturally-defined social interaction patterns are considered to be an important determinant in the spread of diseases that are transmitted through person-to-person contact. Understanding of the contact patterns in this region can be helpful to develop more effective control measures. Focus group discussions were used in exploring social contact patterns in northwest Bangladesh. The patterns were assessed for perceived relevance to the spread of airborne infectious diseases, with special focus on diseases, like leprosy and tuberculosis, in which the role of social determinants is well-recognized. Highly-relevant social contact patterns inside the home and the neighbourhood, across age and sex groups, were reported in all group discussions. Outside the home, women and girls reported relevant contacts limited to the close neighbourhood while men mentioned high relevant contacts beyond. This implies that, in theory, infectious diseases can easily be transmitted across age and sex groups in and around the home. Adult men might play a role in the transmission of airborne infectious diseases from outside this confined area since only this group reported highly-relevant social contacts beyond the home. This concept needs further exploration but control programmes in the South Asian region could benefit from considering differences in social contact patterns by gender for risk assessments and planning of preventive interventions.

Contact Profiles in Eight European Countries and Implications for Modelling the Spread of Airborne Infectious Diseases

BackgroundFor understanding the spread of infectious diseases it is crucial to have knowledge of the patterns of contacts in a population during which the infection can be transmitted. Besides contact rates and mixing between age groups, the way individuals distribute their contacts across different locations may play an important role in determining how infections spread through a population.Methods and FindingsRepresentative surveys were performed in eight countries to assess the number of social contacts (talking to another person at close distance either with or without physical contact), using a diary approach in which participants recorded individual contacts. The overall sample size was 7290 respondents. We analyzed the reported numbers of contacts per respondent in six different settings (household, work, school, leisure, transportation and others) to define different contact profiles. The identification of the profiles and classification of respondents according to these profiles was conducted using a two-step cluster analysis algorithm as implemented in SPSS.We identified seven distinct contact profiles: respondents having (1) mixed: contacts predominantly at school, during transportation and leisure time, (2) contacts during leisure time, (3) contacts mainly in the household (large family), (4) contacts at work, (5) contacts solely at school, (6) contacts in other places and finally (7) respondents having a low number of contacts in any setting. Similar contact profiles can be found in all eight European countries which participated in the study. The distributions of respondents across the profiles were similar in all countries. The profiles are dominated by work, school and household contacts. But also contacts during leisure activities play an important role in the daily lives of a large fraction of individuals. A surprisingly large number of individuals has only few contacts in all locations. There was a distinct age-dependence in the distribution of the population across contact profiles.ConclusionsIn contrast with earlier studies that focussed on the contribution of different age groups to the spread of an infectious disease, our results open up the opportunity to analyze how an infection spreads between locations and how locations as work or school are interconnected via household contacts. Mathematical models that take these local contact patterns into account can be used to assess the effect of intervention measures like school closure and cancelling of leisure activities on the spread of influenza.

Role of ventilation in airborne transmission of infectious agents in the built environment ? a multidisciplinary systematic review

There have been few recent studies demonstrating a definitive association between the transmission of airborne infections and the ventilation of buildings. The severe acute respiratory syndrome (SARS) epidemic in 2003 and current concerns about the risk of an avian influenza (H5N1) pandemic, have made a review of this area timely. We searched the major literature databases between 1960 and 2005, and then screened titles and abstracts, and finally selected 40 original studies based on a set of criteria. We established a review panel comprising medical and engineering experts in the fields of microbiology, medicine, epidemiology, indoor air quality, building ventilation, etc. Most panel members had experience with research into the 2003 SARS epidemic. The panel systematically assessed 40 original studies through both individual assessment and a 2-day face-to-face consensus meeting. Ten of 40 studies reviewed were considered to be conclusive with regard to the association between building ventilation and the transmission of airborne infection. There is strong and sufficient evidence to demonstrate the association between ventilation, air movements in buildings and the transmission/spread of infectious diseases such as measles, tuberculosis, chickenpox, influenza, smallpox and SARS. There is insufficient data to specify and quantify the minimum ventilation requirements in hospitals, schools, offices, homes and isolation rooms in relation to spread of infectious diseases via the airborne route. PRACTICAL IMPLICATION: The strong and sufficient evidence of the association between ventilation, the control of airflow direction in buildings, and the transmission and spread of infectious diseases supports the use of negatively pressurized isolation rooms for patients with these diseases in hospitals, in addition to the use of other engineering control methods. However, the lack of sufficient data on the specification and quantification of the minimum ventilation requirements in hospitals, schools and offices in relation to the spread of airborne infectious diseases, suggest the existence of a knowledge gap. Our study reveals a strong need for a multidisciplinary study in investigating disease outbreaks, and the impact of indoor air environments on the spread of airborne infectious diseases.

Who mixes with whom? A method to determine the contact patterns of adults that may lead to the spread of airborne infections.

Although mixing patterns are thought to be important determinants of the spread of airborne infectious diseases, to our knowledge, there have been no attempts to directly quantify them for humans. We report on a preliminary study to identify such mixing patterns. A sample of 92 adults were asked to detail the individuals with whom they had conversed over the period of one, randomly assigned, day. Sixty-five (71%) completed the questionnaire, providing their age, the age of their contacts and the social context in which the contacts took place. The data were analysed using multilevel modelling. The study identified, and allowed the quantification of, contact patterns within this sample that may be of epidemiological significance. For example, the degree of assortativeness of mixing with respect to age was dependent not only on the age of participants but the number of contacts made. Estimates of the relative magnitude of contact rates between different social settings were made, with implications for outbreak potential. Simple questionnaire modifications are suggested which would yield information on the structure and dynamics of social networks and the intensity of contacts. Surveys of this nature may enable the quantification of who acquires infection from whom and from where.