Aspects regarding numerical models for safe evacuation of people, in the current pandemic context

In everyday life, several situations can be mentioned in which a building or a complex of buildings may require emergency evacuation: fires, chemical leaks, release of toxic or explosive gases, explosions, violent behavior, or threats with weapons/bombs. To calculate the time needed for building evacuation, numerical models are used to simulate this process of movement of groups of people, in a closed physical space. Algorithms for access path and exit selection use both properties of the crowds model and the individual interaction between event and people. The pandemic context has raised several questions about the safe use of buildings, given the presence of the risk of disease transmission. The policies adopted in the last year regarding the use of buildings, establishing access flows, and social distance, vary within great limits, being specific to each state and based on the analysis of the virus transmission rate rather than on risk assessments at the building level. The paper aims to present the main challenges to which the models of emergency evacuation, must respond, especially those considering social distancing and interaction between individuals, within a given distance, all to minimize the risk of disease transmission during the evacuation process of the building.

Download Full-text

A Multistory Building Evacuation Model Based on Multiple-Factor Analysis

Advances in Civil Engineering ◽

10.1155/2019/6585102 ◽

2019 ◽

Vol 2019 ◽

pp. 1-14

Author(s):

Yang Zhou ◽

Tanghong Wu ◽

Gaofan Zhang ◽

Zichuan Fan

Keyword(s):

Functional Relationship ◽

Emergency Evacuation ◽

Multiple Factor Analysis ◽

Time Step ◽

Evacuation Time ◽

Building Evacuation ◽

Access Path ◽

Multistory Building ◽

Evacuation Model ◽

Evacuation Routes

Emergency evacuation is an important issue in public security. To make a considerate plan, various situations are presented including blocking the accident area and letting the emergency access path available. In order to offer dynamic evacuation routes due to different circumstances, a multistory building evacuation model is proposed. Firstly, to analyse the patency of the building, an evacuation formula is applied after binary processing. The function of evacuation time and some other parameters is given by means of regression analysis. Secondly, the cellular automata (CA) algorithm was applied to illustrate the effect of the bottleneck. The response of evacuation time could be approximately optimized through calculating time step of the CA simulation. Finally, the value of maximum evacuation population density could be determined according to the analysis of CA simulation results, which was related to the switch state of the emergency channel. The emergency evacuation model was simulated by using the Louvre museum as an example. The results of the simulation presented some feasible evacuation routes in all kinds of situations. Furthermore, the functional relationship would also be given among evacuation time with the diversity of tourists, pedestrian density, and width of exits. It can give a different perspective that the multistory building evacuation model shows excellent adaptability to different circumstances.

Download Full-text

Gastrointestinal Endoscopy in the Era of COVID-19

Frontiers in Medicine ◽

10.3389/fmed.2020.587602 ◽

2020 ◽

Vol 7 ◽

Author(s):

Abhilash Perisetti ◽

Hemant Goyal ◽

Neil Sharma

Keyword(s):

Disease Transmission ◽

Gastrointestinal Endoscopy ◽

Significant Proportion ◽

Virus Transmission ◽

Healthcare Systems ◽

Financial Strain ◽

Protective Equipment ◽

Dynamic Approach ◽

Risk Of Disease ◽

Mandatory Use

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which led to a worldwide pandemic that started in early 2020. Healthcare systems across the world encountered an unprecedented surge of COVID-19 patients resulting in more than half a million deaths globally. COVID-19 has affected multiple sub-specialties and procedure-related fields, including gastroenterology. Gastrointestinal (GI) endoscopy centers are specialized units where thousands of endoscopies are performed annually. A significant proportion of these procedures are affected due to the national and regional lockdowns across the globe. To adapt to this rapidly evolving situation, endoscopy centers have undergone significant changes and have taken unprecedented precautions to avoid the transmission of the virus. However, endoscopy centers are going through financial strain due to a reduction in the number of procedures from lockdowns and fear of virus transmission. Theoretically, endoscopies could add to the disease transmission as SARS-CoV-2 has shown to be present in the GI secretions. Multiple precautions such as mandatory use of face masks, safe distancing, use of barriers between the endoscopists and patients, negative pressure rooms, extended use of personal protective equipment, and volume reduction have been taken to decrease the risk of disease transmission by these centers. Moreover, pre-endoscopy COVID-19 testing has now become the norm. In this review, we highlight the significant changes assumed by the endoscopy center. Furthermore, we discuss cost-related concerns of pre-endoscopy COVID-19 testing, the downtime and delays related to the procedures, and effects of rescheduling. As the pandemic progresses through multiple phases, endoscopy centers should use a dynamic approach to adapt and strive to provide the best patient care.

Download Full-text

Mathematical Modelling For Decision Making of Lockdown during COVID-19

10.21203/rs.3.rs-42770/v1 ◽

2020 ◽

Author(s):

Ahona Ghosh ◽

Sandip Roy ◽

Suparna Biswas

Keyword(s):

Disease Transmission ◽

Reproduction Number ◽

Transmission Rate ◽

Virus Transmission ◽

Business Travel ◽

Travel And Tourism ◽

Quick Recovery ◽

Experimental Findings ◽

Tourism Economy ◽

Education Business

Abstract Due to the recent worldwide outbreak of COVID-19, there has been a huge change in our lifestyle and it has a severe impact in different fields like finance, education, business, travel and tourism, economy in all the affected countries. In this scenario, people have to be careful and cautious about the symptoms and should act accordingly. Accurate predictions of factors, like the end date of the pandemic, duration of lockdown and spreading trend can guide us through the situation and precautions should be taken wisely. Multiple attempts have been made to model the virus transmission, but none of them has investigated it at a global level and concepts like recovery trend analysis in the developed and developing countries have not been discussed ever. The novelty of our proposed work lies here. In this paper, we have analysed the nature of spreading of the said disease using Time Dependent Discrete Susceptible Infected Recovered (TDDSIR) model on the data collected from various platforms and then, fifteen countries from first, second and third world have been considered to have an idea of probable future projections of pandemic. Experimental findings proved that proper social distancing measures during lockdown has been a controller of the disease transmission trend as the basic reproduction number, being actually the transmission rate and not the number of infectives, decreases with the strict lockdown decisions made by different countries. However, people should be more aware of the consequences for quick recovery from the various obstacles of the current situation.

Download Full-text

Dynamics of the COVID-19 epidemic in Ireland under mitigation

BMC Infectious Diseases ◽

10.1186/s12879-021-06433-9 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Bernard Cazelles ◽

Benjamin Nguyen-Van-Yen ◽

Clara Champagne ◽

Catherine Comiskey

Keyword(s):

Transmission Rate ◽

Vaccination Campaign ◽

Virus Transmission ◽

Reporting Rate ◽

Mitigation Measures ◽

Third Wave ◽

The European Union ◽

Hospital Data ◽

Prevalence Survey ◽

Epidemic Curve

Abstract Background In Ireland and across the European Union the COVID-19 epidemic waves, driven mainly by the emergence of new variants of the SARS-CoV-2 have continued their course, despite various interventions from governments. Public health interventions continue in their attempts to control the spread as they wait for the planned significant effect of vaccination. Methods To tackle this challenge and the observed non-stationary aspect of the epidemic we used a modified SEIR stochastic model with time-varying parameters, following Brownian process. This enabled us to reconstruct the temporal evolution of the transmission rate of COVID-19 with the non-specific hypothesis that it follows a basic stochastic process constrained by the available data. This model is coupled with Bayesian inference (particle Markov Chain Monte Carlo method) for parameter estimation and utilized mainly well-documented Irish hospital data. Results In Ireland, mitigation measures provided a 78–86% reduction in transmission during the first wave between March and May 2020. For the second wave in October 2020, our reduction estimation was around 20% while it was 70% for the third wave in January 2021. This third wave was partly due to the UK variant appearing in Ireland. In June 2020 we estimated that sero-prevalence was 2.0% (95% CI: 1.2–3.5%) in complete accordance with a sero-prevalence survey. By the end of April 2021, the sero-prevalence was greater than 17% due in part to the vaccination campaign. Finally we demonstrate that the available observed confirmed cases are not reliable for analysis owing to the fact that their reporting rate has as expected greatly evolved. Conclusion We provide the first estimations of the dynamics of the COVID-19 epidemic in Ireland and its key parameters. We also quantify the effects of mitigation measures on the virus transmission during and after mitigation for the three waves. Our results demonstrate that Ireland has significantly reduced transmission by employing mitigation measures, physical distancing and lockdown. This has to date avoided the saturation of healthcare infrastructures, flattened the epidemic curve and likely reduced mortality. However, as we await for a full roll out of a vaccination programme and as new variants potentially more transmissible and/or more infectious could continue to emerge and mitigation measures change silent transmission, challenges remain.

Download Full-text

Estimating asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan: a mathematical modeling study

BMC Infectious Diseases ◽

10.1186/s12879-021-06078-8 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Xi Huo ◽

Jing Chen ◽

Shigui Ruan

Keyword(s):

Disease Transmission ◽

Large Scale ◽

Transmission Rate ◽

Control Strategies ◽

Herd Immunity ◽

Antibody Prevalence ◽

Screening Process ◽

Vaccination Programs ◽

Prevalence Level ◽

The Impact

Abstract Background The COVID-19 outbreak in Wuhan started in December 2019 and was under control by the end of March 2020 with a total of 50,006 confirmed cases by the implementation of a series of nonpharmaceutical interventions (NPIs) including unprecedented lockdown of the city. This study analyzes the complete outbreak data from Wuhan, assesses the impact of these public health interventions, and estimates the asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan. Methods By taking different stages of the outbreak into account, we developed a time-dependent compartmental model to describe the dynamics of disease transmission and case detection and reporting. Model coefficients were parameterized by using the reported cases and following key events and escalated control strategies. Then the model was used to calibrate the complete outbreak data by using the Monte Carlo Markov Chain (MCMC) method. Finally we used the model to estimate asymptomatic and undetected cases and approximate the overall antibody prevalence level. Results We found that the transmission rate between Jan 24 and Feb 1, 2020, was twice as large as that before the lockdown on Jan 23 and 67.6% (95% CI [0.584,0.759]) of detectable infections occurred during this period. Based on the reported estimates that around 20% of infections were asymptomatic and their transmission ability was about 70% of symptomatic ones, we estimated that there were about 14,448 asymptomatic and undetected cases (95% CI [12,364,23,254]), which yields an estimate of a total of 64,454 infected cases (95% CI [62,370,73,260]), and the overall antibody prevalence level in the population of Wuhan was 0.745% (95% CI [0.693%,0.814%]) by March 31, 2020. Conclusions We conclude that the control of the COVID-19 outbreak in Wuhan was achieved via the enforcement of a combination of multiple NPIs: the lockdown on Jan 23, the stay-at-home order on Feb 2, the massive isolation of all symptomatic individuals via newly constructed special shelter hospitals on Feb 6, and the large scale screening process on Feb 18. Our results indicate that the population in Wuhan is far away from establishing herd immunity and provide insights for other affected countries and regions in designing control strategies and planing vaccination programs.

Download Full-text

Livestock movement informs the risk of disease spread in traditional production systems in East Africa

Scientific Reports ◽

10.1038/s41598-021-95706-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Divine Ekwem ◽

Thomas A. Morrison ◽

Richard Reeve ◽

Jessica Enright ◽

Joram Buza ◽

...

Keyword(s):

Disease Transmission ◽

Production Systems ◽

Control Strategies ◽

Herd Size ◽

Transmission Risk ◽

Disease Spread ◽

Transmission Potential ◽

Spatial And Temporal Scales ◽

Transmission Distance ◽

Risk Of Disease

AbstractIn Africa, livestock are important to local and national economies, but their productivity is constrained by infectious diseases. Comprehensive information on livestock movements and contacts is required to devise appropriate disease control strategies; yet, understanding contact risk in systems where herds mix extensively, and where different pathogens can be transmitted at different spatial and temporal scales, remains a major challenge. We deployed Global Positioning System collars on cattle in 52 herds in a traditional agropastoral system in western Serengeti, Tanzania, to understand fine-scale movements and between-herd contacts, and to identify locations of greatest interaction between herds. We examined contact across spatiotemporal scales relevant to different disease transmission scenarios. Daily cattle movements increased with herd size and rainfall. Generally, contact between herds was greatest away from households, during periods with low rainfall and in locations close to dipping points. We demonstrate how movements and contacts affect the risk of disease spread. For example, transmission risk is relatively sensitive to the survival time of different pathogens in the environment, and less sensitive to transmission distance, at least over the range of the spatiotemporal definitions of contacts that we explored. We identify times and locations of greatest disease transmission potential and that could be targeted through tailored control strategies.

Download Full-text

The effects of flooding and weather conditions on leptospirosis transmission in Thailand

Scientific Reports ◽

10.1038/s41598-020-79546-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sudarat Chadsuthi ◽

Karine Chalvet-Monfray ◽

Anuwat Wiratsudakul ◽

Charin Modchang

Keyword(s):

Sensitivity Analysis ◽

Public Education ◽

Mathematical Models ◽

Disease Transmission ◽

Transmission Rate ◽

Weather Conditions ◽

Transmission Dynamics ◽

Multiplication Rate ◽

High Degree ◽

Transmission Models

AbstractThe epidemic of leptospirosis in humans occurs annually in Thailand. In this study, we have developed mathematical models to investigate transmission dynamics between humans, animals, and a contaminated environment. We compared different leptospire transmission models involving flooding and weather conditions, shedding and multiplication rate in a contaminated environment. We found that the model in which the transmission rate depends on both flooding and temperature, best-fits the reported human data on leptospirosis in Thailand. Our results indicate that flooding strongly contributes to disease transmission, where a high degree of flooding leads to a higher number of infected individuals. Sensitivity analysis showed that the transmission rate of leptospires from a contaminated environment was the most important parameter for the total number of human cases. Our results suggest that public education should target people who work in contaminated environments to prevent Leptospira infections.

Download Full-text

Characteristics of diluted-stored and post-thawed semen of Hutsul stallions

Acta Veterinaria Hungarica ◽

10.1556/004.2021.00050 ◽

2021 ◽

Keyword(s):

Sperm Motility ◽

Disease Transmission ◽

Survival Rates ◽

Genetic Material ◽

Sperm Bank ◽

Resource Protection ◽

Frozen Semen ◽

Genetic Reserve ◽

Basic Parameters ◽

Risk Of Disease

Abstract The use of frozen semen lowers the risk of disease transmission, eliminates geographical limitations and supports the implementation of genetic resource protection programs. However, due to the very rare use of frozen semen from Hutsul stallions, their genetic material is not secured in sperm banks, and very little information is available about their semen, including its suitability for cryopreservation, and sperm survival rates after thawing. The aim of this study was to analyse basic parameters such as sperm motility, vitality and morphology in diluted-stored and post-thawed Hutsul semen, using a CASA system. There were no differences in sperm motility (P = 0.3372) or morphology between the groups, although the progressive motility was higher in thawed semen (P = 0.0151), while the sperm vitality was higher in diluted-stored semen (P = 0.00517). This study demonstrates that semen from Hutsul horses is suitable for cryopreservation, thus supporting the creation of a sperm bank as a genetic reserve for representatives of this breed.

Download Full-text

Mother-child transmission of Chagas disease: could coinfection with human immunodeficiency virus increase the risk?

Revista da Sociedade Brasileira de Medicina Tropical ◽

10.1590/s0037-86822009000200002 ◽

2009 ◽

Vol 42 (2) ◽

pp. 107-109 ◽

Cited By ~ 30

Author(s):

Pablo Gustavo Scapellato ◽

Edgardo Gabriel Bottaro ◽

María Teresa Rodríguez-Brieschke

Keyword(s):

Human Immunodeficiency Virus ◽

Trypanosoma Cruzi ◽

Chagas Disease ◽

Vertical Transmission ◽

Disease Transmission ◽

Transmission Rate ◽

Buffy Coat ◽

Child Transmission ◽

Serological Tests ◽

Immunodeficiency Virus

A study was conducted on all newborns from mothers with Chagas disease who were attended at Hospital Donación F. Santojanni between January 1, 2001, and August 31, 2007. Each child was investigated for the presence of Trypanosoma cruzi parasitemia through direct examination of blood under the microscope using the buffy coat method on three occasions during the first six months of life. Serological tests were then performed. Ninety-four children born to mothers infected with Trypanosoma cruzi were attended over the study period. Three of these children were born to mothers coinfected with the human immunodeficiency virus. Vertical transmission of Chagas disease was diagnosed in 13 children, in all cases by identifying parasitemia. The overall Chagas disease transmission rate was 13.8% (13/94). It was 100% (3/3) among the children born to mothers with HIV infection and 10.9% (10/91) among children born to mothers without HIV [Difference = 0.89; CI95 = 0.82-0.95; p = 0.0021]. We concluded that coinfection with HIV could increase the risk of vertical transmission of Chagas disease.

Download Full-text

Telemedicine: A Paradigm Shift in Healthcare in the wake of COVID-19 in India

JOURNAL FOR CLINICAL AND DIAGNOSTIC RESEARCH ◽

10.7860/jcdr/2020/46459.14295 ◽

2020 ◽

Author(s):

Ria Saha ◽

Vinoth Gnana Chellaiyan

Keyword(s):

Disease Transmission ◽

Healthcare Services ◽

National Guidelines ◽

Medical Practitioners ◽

Regulatory Guidelines ◽

Risk Of Disease ◽

Wide Scale ◽

The Government ◽

Institutional Challenges

The COVID-19 pandemic has severely affected the delivery of essential healthcare services in India. The massive disruption of the routine healthcare services had been circumvented to a certain extent with the application of telemedicine. In the wake of the COVID-19 pandemic, the Government of India has issued regulatory guidelines and approved Registered Medical Practitioners (RMP) to adopt the usage of teleconsultation service which can be real-time or asynchronous to minimise the risk of disease transmission. The commentary provides an in-depth review of the regulatory guidelines implemented by the Government of India and discusses the inherent structural and fundamental challenges associated with its wide scale adoption, accessibility, and utilisation. Though the Government of India had issued national guidelines to promote safe and effective usage of telemedicine practice, there remains certain primary structural, technical and institutional challenges regarding expansion of uninterrupted services to periurban and rural peripheral health facilities and its nationwide sustainability. The article demands the attention of the policymakers and relevant stakeholders to identify the inherent bottlenecks intrinsic to the guidelines and amend the regulatory framework accordingly to ensure its long-term sustainability.

Download Full-text