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1.
Annu Int Conf IEEE Eng Med Biol Soc ; 2021: 2286-2289, 2021 11.
Article in English | MEDLINE | ID: covidwho-1799329

ABSTRACT

The use of network models to study the spread of infectious diseases is gaining increasing interests. They allow the flexibility to represent epidemic systems as networks of components with complex and interconnected structures. However, most of previous studies are based on networks of individuals as nodes and their social relationships (e.g., friendship, workplace connections) as links during the virus spread process. Notably, the transmission and spread of infectious viruses are more pertinent to human dynamics (e.g., their movements and interactions with others) in the spatial environment. This paper presents a novel network-based simulation model of human traffic and virus spread in community networks. We represent spatial points of interests (POI) as nodes where human subjects interact and perform activities, while edges connect these POIs to form a community network. Specifically, we derive the spatial network from the geographical information systems (GIS) data to provide a detailed representation of the underlying community network, on which human subjects perform activities and form traffics that impact the process of virus transmission and spread. The proposed framework is evaluated and validated in a community of university campus. Experimental results showed that the proposed simulation model is capable of describing interactive human activities at an individual level, as well as capturing the spread dynamics of infectious diseases. This framework can be extended to a wide variety of infectious diseases and shows strong potentials to aid the design of intervention policies for epidemic control.


Subject(s)
Epidemics , Virus Diseases/transmission , Computer Simulation , Humans
3.
5.
Viruses ; 14(1)2022 01 14.
Article in English | MEDLINE | ID: covidwho-1625756

ABSTRACT

Bats are reservoirs of a large number of viruses of global public health significance, including the ancestral virus for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the causative agent of coronavirus disease 2019 (COVID-19). Although bats are natural carriers of multiple pathogenic viruses, they rarely display signs of disease. Recent insights suggest that bats have a more balanced host defense and tolerance system to viral infections that may be linked to the evolutionary adaptation to powered flight. Therefore, a deeper understanding of bat immune system may provide intervention strategies to prevent zoonotic disease transmission and to identify new therapeutic targets. Similar to other eutherian mammals, bats have both innate and adaptive immune systems that have evolved to detect and respond to invading pathogens. Bridging these two systems are innate lymphocytes, which are highly abundant within circulation and barrier tissues. These cells share the characteristics of both innate and adaptive immune cells and are poised to mount rapid effector responses. They are ideally suited as the first line of defense against early stages of viral infections. Here, we will focus on the current knowledge of innate lymphocytes in bats, their function, and their potential role in host-pathogen interactions. Moreover, given that studies into bat immune systems are often hindered by a lack of bat-specific research tools, we will discuss strategies that may aid future research in bat immunity, including the potential use of organoid models to delineate the interplay between innate lymphocytes, bat viruses, and host tolerance.


Subject(s)
Chiroptera/immunology , Host-Pathogen Interactions/immunology , Immunity, Innate/immunology , Lymphocytes/immunology , Animals , Chiroptera/virology , Disease Reservoirs/virology , Humans , Immune Tolerance , Virus Diseases/immunology , Virus Diseases/transmission , Viruses/pathogenicity
6.
J Exp Med ; 219(2)2022 02 07.
Article in English | MEDLINE | ID: covidwho-1593236

ABSTRACT

Emerging viruses threaten global health, but few experimental models can characterize the virus and host factors necessary for within- and cross-species transmission. Here, we leverage a model whereby pet store mice or rats-which harbor natural rodent pathogens-are cohoused with laboratory mice. This "dirty" mouse model offers a platform for studying acute transmission of viruses between and within hosts via natural mechanisms. We identified numerous viruses and other microbial species that transmit to cohoused mice, including prospective new members of the Coronaviridae, Astroviridae, Picornaviridae, and Narnaviridae families, and uncovered pathogen interactions that promote or prevent virus transmission. We also evaluated transmission dynamics of murine astroviruses during transmission and spread within a new host. Finally, by cohousing our laboratory mice with the bedding of pet store rats, we identified cross-species transmission of a rat astrovirus. Overall, this model system allows for the analysis of transmission of natural rodent viruses and is a platform to further characterize barriers to zoonosis.


Subject(s)
Disease Models, Animal , Disease Susceptibility , Virus Diseases/etiology , Virus Diseases/transmission , Animal Diseases/transmission , Animal Diseases/virology , Animals , Biomarkers , Host-Pathogen Interactions , Humans , Interferons/metabolism , Mice , Mice, Knockout , Microbial Interactions , Rodentia , Virus Diseases/metabolism
7.
PLoS Biol ; 19(4): e3001135, 2021 04.
Article in English | MEDLINE | ID: covidwho-1508487

ABSTRACT

Identifying the animal reservoirs from which zoonotic viruses will likely emerge is central to understanding the determinants of disease emergence. Accordingly, there has been an increase in studies attempting zoonotic "risk assessment." Herein, we demonstrate that the virological data on which these analyses are conducted are incomplete, biased, and rapidly changing with ongoing virus discovery. Together, these shortcomings suggest that attempts to assess zoonotic risk using available virological data are likely to be inaccurate and largely only identify those host taxa that have been studied most extensively. We suggest that virus surveillance at the human-animal interface may be more productive.


Subject(s)
Environmental Monitoring , Virus Diseases , Zoonoses/etiology , Zoonoses/prevention & control , Animals , Biodiversity , Disease Reservoirs/classification , Disease Reservoirs/statistics & numerical data , Environmental Monitoring/methods , Environmental Monitoring/standards , Host Specificity/genetics , Humans , Metagenomics/methods , Metagenomics/organization & administration , Metagenomics/standards , Phylogeny , Risk Assessment , Risk Factors , Selection Bias , Virus Diseases/epidemiology , Virus Diseases/etiology , Virus Diseases/prevention & control , Virus Diseases/transmission , Viruses/classification , Viruses/genetics , Viruses/isolation & purification , Viruses/pathogenicity , Zoonoses/epidemiology , Zoonoses/virology
8.
Appl Environ Microbiol ; 87(22): e0121521, 2021 10 28.
Article in English | MEDLINE | ID: covidwho-1494942

ABSTRACT

Fomites can represent a reservoir for pathogens, which may be subsequently transferred from surfaces to skin. In this study, we aim to understand how different factors (including virus type, surface type, time since last hand wash, and direction of transfer) affect virus transfer rates, defined as the fraction of virus transferred, between fingerpads and fomites. To determine this, 360 transfer events were performed with 20 volunteers using Phi6 (a surrogate for enveloped viruses), MS2 (a surrogate for nonenveloped viruses), and three clean surfaces (stainless steel, painted wood, and plastic). Considering all transfer events (all surfaces and both transfer directions combined), the mean transfer rates of Phi6 and MS2 were 0.17 and 0.26, respectively. Transfer of MS2 was significantly higher than that of Phi6 (P < 0.05). Surface type was a significant factor that affected the transfer rate of Phi6: Phi6 is more easily transferred to and from stainless steel and plastic than to and from painted wood. Direction of transfer was a significant factor affecting MS2 transfer rates: MS2 is more easily transferred from surfaces to fingerpads than from fingerpads to surfaces. Data from these virus transfer events, and subsequent transfer rate distributions, provide information that can be used to refine quantitative microbial risk assessments. This study provides a large-scale data set of transfer events with a surrogate for enveloped viruses, which extends the reach of the study to the role of fomites in the transmission of human enveloped viruses like influenza and SARS-CoV-2. IMPORTANCE This study created a large-scale data set for the transfer of enveloped viruses between skin and surfaces. The data set produced by this study provides information on modeling the distribution of enveloped and nonenveloped virus transfer rates, which can aid in the implementation of risk assessment models in the future. Additionally, enveloped and nonenveloped viruses were applied to experimental surfaces in an equivalent matrix to avoid matrix effects, so results between different viral species can be directly compared without confounding effects of different matrices. Our results indicating how virus type, surface type, time since last hand wash, and direction of transfer affect virus transfer rates can be used in decision-making processes to lower the risk of viral infection from transmission through fomites.


Subject(s)
Fingers/virology , Fomites/virology , Virus Physiological Phenomena , Bacteriophage phi 6/physiology , Bacteriophage phi 6/ultrastructure , Fomites/classification , Hand Hygiene , Humans , Levivirus/physiology , Levivirus/ultrastructure , Viral Envelope/ultrastructure , Virus Diseases/transmission , Virus Diseases/virology , Viruses/ultrastructure
9.
Postgrad Med J ; 98(1156): 131-137, 2022 Feb.
Article in English | MEDLINE | ID: covidwho-1452953

ABSTRACT

Lower respiratory infections are often caused or precipitated by viruses and are a leading cause of global morbidity and mortality. Mutations in these viral genomes can produce highly infectious strains that transmit across species and have the potential to initiate epidemic, or pandemic, human viral respiratory disease. Transmission between humans primarily occurs via the airborne route and is accelerated by our increasingly interconnected and globalised society. To this date, there have been four major human viral respiratory outbreaks in the 21st century. Healthcare workers (HCWs) are at particular risk during respiratory epidemics or pandemics. This is due to crowded working environments where social distancing, or wearing respiratory personal protective equipment for prolonged periods, might prove difficult, or performing medical procedures that increase exposure to virus-laden aerosols, or bodily fluids. This review aims to summarise the evidence and approaches to occupational risk and protection of HCWs during epidemic or pandemic respiratory viral disease.


Subject(s)
Communicable Diseases , Health Personnel/psychology , Occupational Exposure/prevention & control , Pandemics/prevention & control , Personal Protective Equipment , Respiratory Tract Infections/prevention & control , Virus Diseases/prevention & control , Communicable Disease Control , Humans , Occupational Health , Respiratory Tract Infections/epidemiology , Respiratory Tract Infections/virology , Virus Diseases/transmission , Workplace
10.
Viruses ; 13(7)2021 07 02.
Article in English | MEDLINE | ID: covidwho-1445747

ABSTRACT

Pandemics are a consequence of a series of processes that span scales from viral biology at 10-9 m to global transmission at 106 m. The pathogen passes from one host species to another through a sequence of events that starts with an infected reservoir host and entails interspecific contact, innate immune responses, receptor protein structure within the potential host, and the global spread of the novel pathogen through the naive host population. Each event presents a potential barrier to the onward passage of the virus and should be characterized with an integrated transdisciplinary approach. Epidemic control is based on the prevention of exposure, infection, and disease. However, the ultimate pandemic prevention is prevention of the spillover event itself. Here, we focus on the potential for preventing the spillover of henipaviruses, a group of viruses derived from bats that frequently cross species barriers, incur high human mortality, and are transmitted among humans via stuttering chains. We outline the transdisciplinary approach needed to prevent the spillover process and, therefore, future pandemics.


Subject(s)
Chiroptera/virology , Global Health , Henipavirus Infections/prevention & control , Henipavirus/pathogenicity , Pandemics/prevention & control , Virus Diseases/prevention & control , Zoonoses/virology , Animals , Henipavirus Infections/epidemiology , Henipavirus Infections/immunology , Henipavirus Infections/transmission , Host Specificity , Humans , Immunity, Innate , Nipah Virus/pathogenicity , Virus Diseases/immunology , Virus Diseases/transmission , Zoonoses/prevention & control , Zoonoses/transmission
11.
Int Health ; 12(2): 77-85, 2020 02 12.
Article in English | MEDLINE | ID: covidwho-1387916

ABSTRACT

BACKGROUND: Strategies are urgently needed to mitigate the risk of zoonotic disease emergence in southern China, where pathogens with zoonotic potential are known to circulate in wild animal populations. However, the risk factors leading to emergence are poorly understood, which presents a challenge in developing appropriate mitigation strategies for local communities. METHODS: Residents in rural communities of Yunnan, Guangxi and Guangdong provinces were recruited and enrolled in this study. Data were collected through ethnographic interviews and field observations, and thematically coded and analysed to identify both risk and protective factors for zoonotic disease emergence at the individual, community and policy levels. RESULTS: Eighty-eight ethnographic interviews and 55 field observations were conducted at nine selected sites. Frequent human-animal interactions and low levels of environmental biosecurity in local communities were identified as risks for zoonotic disease emergence. Policies and programmes existing in the communities provide opportunities for zoonotic risk mitigation. CONCLUSIONS: This study explored the relationship among zoonotic risk and human behaviour, environment and policies in rural communities in southern China. It identifies key behavioural risk factors that can be targeted for development of tailored risk-mitigation strategies to reduce the threat of novel zoonoses.


Subject(s)
Animals, Wild/virology , Communicable Diseases, Emerging/transmission , Coronavirus Infections/transmission , Disease Outbreaks/prevention & control , Pneumonia, Viral/transmission , Rural Population , Virus Diseases/transmission , Zoonoses/transmission , Adolescent , Adult , Animals , Betacoronavirus , COVID-19 , China/epidemiology , Communicable Diseases, Emerging/epidemiology , Communicable Diseases, Emerging/virology , Coronavirus Infections/epidemiology , Coronavirus Infections/prevention & control , Female , Health Knowledge, Attitudes, Practice , Humans , Interviews as Topic , Male , Middle Aged , Pneumonia, Viral/epidemiology , Pneumonia, Viral/prevention & control , Qualitative Research , Risk Factors , SARS-CoV-2 , Severe Acute Respiratory Syndrome , Virus Diseases/epidemiology , Young Adult , Zoonoses/epidemiology , Zoonoses/virology
13.
Biochim Biophys Acta Mol Basis Dis ; 1867(12): 166264, 2021 12 01.
Article in English | MEDLINE | ID: covidwho-1385051

ABSTRACT

The molecular evolution of life on earth along with changing environmental, conditions has rendered mankind susceptible to endemic and pandemic emerging infectious diseases. The effects of certain systemic viral and bacterial infections on morbidity and mortality are considered as examples of recent emerging infections. Here we will focus on three examples of infections that are important in pregnancy and early childhood: SARS-CoV-2 virus, Zika virus, and Mycoplasma species. The basic structural characteristics of these infectious agents will be examined, along with their general pathogenic mechanisms. Coronavirus infections, such as caused by the SARS-CoV-2 virus, likely evolved from zoonotic bat viruses to infect humans and cause a pandemic that has been the biggest challenge for humanity since the Spanish Flu pandemic of the early 20th century. In contrast, Zika Virus infections represent an expanding infectious threat in the context of global climate change. The relationship of these infections to pregnancy, the vertical transmission and neurological sequels make these viruses highly relevant to the topics of this special issue. Finally, mycoplasmal infections have been present before mankind evolved, but they were rarely identified as human pathogens until recently, and they are now recognized as important coinfections that are able to modify the course and prognosis of various infectious diseases and other chronic illnesses. The infectious processes caused by these intracellular microorganisms are examined as well as some general aspects of their pathogeneses, clinical presentations, and diagnoses. We will finally consider examples of treatments that have been used to reduce morbidity and mortality of these infections and discuss briefly the current status of vaccines, in particular, against the SARS-CoV-2 virus. It is important to understand some of the basic features of these emerging infectious diseases and the pathogens involved in order to better appreciate the contributions of this special issue on how infectious diseases can affect human pregnancy, fetuses and neonates.


Subject(s)
Bacterial Infections/prevention & control , Communicable Diseases/transmission , Virus Diseases/prevention & control , Bacterial Infections/history , Bacterial Infections/transmission , COVID-19/metabolism , COVID-19/prevention & control , Communicable Diseases/virology , Female , History, 19th Century , History, 20th Century , History, 21st Century , Humans , Infant, Newborn , Infectious Disease Transmission, Vertical/history , Mycoplasma/pathogenicity , Mycoplasma Infections/metabolism , Mycoplasma Infections/prevention & control , Pregnancy , Pregnant Women , SARS-CoV-2/pathogenicity , Virus Diseases/history , Virus Diseases/transmission , Zika Virus/pathogenicity , Zika Virus Infection/metabolism , Zika Virus Infection/prevention & control
14.
Environ Sci Pollut Res Int ; 28(40): 56376-56391, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-1384555

ABSTRACT

It is important to know whether SARS-CoV-2 is spread through the air conditioning systems. Taking the central air conditioning system as an example, we analyze the mechanism and potential health risk of respiratory virus transmission in air-conditioned rooms and propose a method to study the risk of virus transmission in central air conditioning systems by investigating the data from medical experiments. The virus carrying capacity and the decay characteristics of indoor pathogen droplets are studied in this research. Additionally, the effects of air temperature and relative humidity on the virus survival in the air or on surfaces are investigated. The removal efficiency of infectious droplet nuclei by using an air conditioning filter was then determined. Thus, the transmission risk during the operation of the centralized air conditioning system is evaluated. The results show that the indoor temperature and humidity are controlled in the range of 20-25 °C and 40-70% by central air conditioning during the epidemic period, which not only benefits the health and comfort of residents, but also weakens the vitality of the virus. The larger the droplet size, the longer the viruses survive. Since the filter efficiency of the air conditioning filter increases with the increase in particle size, increasing the number of air changes of the circulating air volume can accelerate the removal of potential pathogen particles. Therefore, scientific operation of centralized air conditioning systems during the epidemic period has more advantages than disadvantages.


Subject(s)
Air Conditioning , Air Pollution, Indoor , COVID-19 , Viruses , Air Microbiology , Air Pollution, Indoor/analysis , COVID-19/transmission , Humans , Humidity , SARS-CoV-2 , Virus Diseases/transmission
15.
Viruses ; 13(2)2021 02 23.
Article in English | MEDLINE | ID: covidwho-1389526

ABSTRACT

A challenging debate has arisen on the role of veterinary expertise in facing the SARS-CoV-2 pandemic. It seems totally unreasonable that in most countries, veterinary diagnostic and tracing forces were not deployed at the start to perform strategic tasks, which could have mitigated the outcome of this dramatic health emergency. Erasing the invisible line between human and veterinary virology will empower the response to future pandemics.


Subject(s)
Contact Tracing , Pandemics/prevention & control , Veterinary Medicine , Viral Zoonoses , Virus Diseases , Animals , Humans , Viral Zoonoses/epidemiology , Viral Zoonoses/transmission , Virus Diseases/epidemiology , Virus Diseases/transmission , Virus Diseases/veterinary
16.
Viruses ; 13(8)2021 07 31.
Article in English | MEDLINE | ID: covidwho-1376989

ABSTRACT

Rodents (order Rodentia), followed by bats (order Chiroptera), comprise the largest percentage of living mammals on earth. Thus, it is not surprising that these two orders account for many of the reservoirs of the zoonotic RNA viruses discovered to date. The spillover of these viruses from wildlife to human do not typically result in pandemics but rather geographically confined outbreaks of human infection and disease. While limited geographically, these viruses cause thousands of cases of human disease each year. In this review, we focus on three questions regarding zoonotic viruses that originate in bats and rodents. First, what biological strategies have evolved that allow RNA viruses to reside in bats and rodents? Second, what are the environmental and ecological causes that drive viral spillover? Third, how does virus spillover occur from bats and rodents to humans?


Subject(s)
Chiroptera/virology , Disease Reservoirs/virology , Rodentia/virology , Virus Diseases/transmission , Zoonoses/virology , Animals , Disease Outbreaks , Humans , Zoonoses/transmission
17.
Science ; 373(6558)2021 08 27.
Article in English | MEDLINE | ID: covidwho-1376452

ABSTRACT

The COVID-19 pandemic has revealed critical knowledge gaps in our understanding of and a need to update the traditional view of transmission pathways for respiratory viruses. The long-standing definitions of droplet and airborne transmission do not account for the mechanisms by which virus-laden respiratory droplets and aerosols travel through the air and lead to infection. In this Review, we discuss current evidence regarding the transmission of respiratory viruses by aerosols-how they are generated, transported, and deposited, as well as the factors affecting the relative contributions of droplet-spray deposition versus aerosol inhalation as modes of transmission. Improved understanding of aerosol transmission brought about by studies of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection requires a reevaluation of the major transmission pathways for other respiratory viruses, which will allow better-informed controls to reduce airborne transmission.


Subject(s)
Air Microbiology , COVID-19/transmission , Respiratory Tract Infections/transmission , SARS-CoV-2 , Virus Diseases/transmission , Virus Physiological Phenomena , Aerosols , COVID-19/virology , Disease Transmission, Infectious , Humans , Microbial Viability , Particle Size , Respiratory System/virology , Respiratory Tract Infections/virology , SARS-CoV-2/isolation & purification , SARS-CoV-2/physiology , Viral Load , Virus Diseases/virology , Viruses/isolation & purification
18.
Lancet Infect Dis ; 21(9): e296-e301, 2021 09.
Article in English | MEDLINE | ID: covidwho-1371553

ABSTRACT

Adherence to non-pharmaceutical interventions to prevent the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been highly variable across settings, particularly in the USA. In this Personal View, we review data supporting the importance of the viral inoculum (the dose of viral particles from an infected source over time) in increasing the probability of infection in respiratory, gastrointestinal, and sexually transmitted viral infections in humans. We also review the available evidence linking the relationship of the viral inoculum to disease severity. Non-pharmaceutical interventions might reduce the susceptibility to SARS-CoV-2 infection by reducing the viral inoculum when there is exposure to an infectious source. Data from physical sciences research suggest that masks protect the wearer by filtering virus from external sources, and others by reducing expulsion of virus by the wearer. Social distancing, handwashing, and improved ventilation also reduce the exposure amount of viral particles from an infectious source. Maintaining and increasing non-pharmaceutical interventions can help to quell SARS-CoV-2 as we enter the second year of the pandemic. Finally, we argue that even as safe and effective vaccines are being rolled out, non-pharmaceutical interventions will continue to play an essential role in suppressing SARS-CoV-2 transmission until equitable and widespread vaccine administration has been completed.


Subject(s)
COVID-19/prevention & control , Communicable Disease Control/methods , SARS-CoV-2 , Virus Diseases/prevention & control , COVID-19/transmission , Hand Disinfection , Humans , Masks/virology , Physical Distancing , Severity of Illness Index , Ventilation , Virus Diseases/transmission
20.
Indoor Air ; 31(6): 1759-1775, 2021 Nov.
Article in English | MEDLINE | ID: covidwho-1293053

ABSTRACT

This paper applies the Rudnick and Milton method through the dynamic evaluation of the probability of airborne contagion, redefining all parameters and variables in discretized form. To adapt the calculation of the risk of contagion to real needs, scenarios are used to define the presence of people, infected subjects, the hourly production of the quanta of infection, and the calculation of the concentration of CO2 produced by exhalation in the air. Three case studies are discussed: a school, an office, a commercial activity. Complex scenarios include environmental sanitization, a variable number of people, and the possibility of simulating work shifts. The dynamic evaluation of the quanta of infection is also estimated, not foreseen by the Rudnick and Milton model, and involves updating the average values of the equivalent fraction of the indoor air with an improvement in the accuracy of the calculation due to the reduction of improper peaks of the stationary variables.


Subject(s)
Air Pollution, Indoor , Virus Diseases , Aerosols , Air Microbiology , COVID-19 , Humans , Risk Assessment , SARS-CoV-2 , Virus Diseases/transmission
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