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Nature Reviews. Microbiology Aug 2021Human respiratory virus infections lead to a spectrum of respiratory symptoms and disease severity, contributing to substantial morbidity, mortality and economic losses... (Review)
Review
Human respiratory virus infections lead to a spectrum of respiratory symptoms and disease severity, contributing to substantial morbidity, mortality and economic losses worldwide, as seen in the COVID-19 pandemic. Belonging to diverse families, respiratory viruses differ in how easy they spread (transmissibility) and the mechanism (modes) of transmission. Transmissibility as estimated by the basic reproduction number (R) or secondary attack rate is heterogeneous for the same virus. Respiratory viruses can be transmitted via four major modes of transmission: direct (physical) contact, indirect contact (fomite), (large) droplets and (fine) aerosols. We know little about the relative contribution of each mode to the transmission of a particular virus in different settings, and how its variation affects transmissibility and transmission dynamics. Discussion on the particle size threshold between droplets and aerosols and the importance of aerosol transmission for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza virus is ongoing. Mechanistic evidence supports the efficacies of non-pharmaceutical interventions with regard to virus reduction; however, more data are needed on their effectiveness in reducing transmission. Understanding the relative contribution of different modes to transmission is crucial to inform the effectiveness of non-pharmaceutical interventions in the population. Intervening against multiple modes of transmission should be more effective than acting on a single mode.
Topics: Aerosols; COVID-19; Humans; Hygiene; Personal Protective Equipment; SARS-CoV-2
PubMed: 33753932
DOI: 10.1038/s41579-021-00535-6 -
BMC Infectious Diseases Aug 2006Inanimate surfaces have often been described as the source for outbreaks of nosocomial infections. The aim of this review is to summarize data on the persistence of... (Review)
Review
BACKGROUND
Inanimate surfaces have often been described as the source for outbreaks of nosocomial infections. The aim of this review is to summarize data on the persistence of different nosocomial pathogens on inanimate surfaces.
METHODS
The literature was systematically reviewed in MedLine without language restrictions. In addition, cited articles in a report were assessed and standard textbooks on the topic were reviewed. All reports with experimental evidence on the duration of persistence of a nosocomial pathogen on any type of surface were included.
RESULTS
Most gram-positive bacteria, such as Enterococcus spp. (including VRE), Staphylococcus aureus (including MRSA), or Streptococcus pyogenes, survive for months on dry surfaces. Many gram-negative species, such as Acinetobacter spp., Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, Serratia marcescens, or Shigella spp., can also survive for months. A few others, such as Bordetella pertussis, Haemophilus influenzae, Proteus vulgaris, or Vibrio cholerae, however, persist only for days. Mycobacteria, including Mycobacterium tuberculosis, and spore-forming bacteria, including Clostridium difficile, can also survive for months on surfaces. Candida albicans as the most important nosocomial fungal pathogen can survive up to 4 months on surfaces. Persistence of other yeasts, such as Torulopsis glabrata, was described to be similar (5 months) or shorter (Candida parapsilosis, 14 days). Most viruses from the respiratory tract, such as corona, coxsackie, influenza, SARS or rhino virus, can persist on surfaces for a few days. Viruses from the gastrointestinal tract, such as astrovirus, HAV, polio- or rota virus, persist for approximately 2 months. Blood-borne viruses, such as HBV or HIV, can persist for more than one week. Herpes viruses, such as CMV or HSV type 1 and 2, have been shown to persist from only a few hours up to 7 days.
CONCLUSION
The most common nosocomial pathogens may well survive or persist on surfaces for months and can thereby be a continuous source of transmission if no regular preventive surface disinfection is performed.
Topics: Bacterial Infections; Cross Infection; Fomites; Fungi; Gram-Negative Bacteria; Gram-Positive Bacteria; Hospitals; Humans; Mycoses; Virus Diseases; Viruses
PubMed: 16914034
DOI: 10.1186/1471-2334-6-130 -
Annals of Internal Medicine Jan 2021Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiologic agent of coronavirus disease 2019 (COVID-19), has spread globally in a few short months.... (Review)
Review
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiologic agent of coronavirus disease 2019 (COVID-19), has spread globally in a few short months. Substantial evidence now supports preliminary conclusions about transmission that can inform rational, evidence-based policies and reduce misinformation on this critical topic. This article presents a comprehensive review of the evidence on transmission of this virus. Although several experimental studies have cultured live virus from aerosols and surfaces hours after inoculation, the real-world studies that detect viral RNA in the environment report very low levels, and few have isolated viable virus. Strong evidence from case and cluster reports indicates that respiratory transmission is dominant, with proximity and ventilation being key determinants of transmission risk. In the few cases where direct contact or fomite transmission is presumed, respiratory transmission has not been completely excluded. Infectiousness peaks around a day before symptom onset and declines within a week of symptom onset, and no late linked transmissions (after a patient has had symptoms for about a week) have been documented. The virus has heterogeneous transmission dynamics: Most persons do not transmit virus, whereas some cause many secondary cases in transmission clusters called "superspreading events." Evidence-based policies and practices should incorporate the accumulating knowledge about transmission of SARS-CoV-2 to help educate the public and slow the spread of this virus.
Topics: Aerosols; COVID-19; Equipment Contamination; Fomites; Humans; RNA, Viral; Risk Factors; SARS-CoV-2
PubMed: 32941052
DOI: 10.7326/M20-5008 -
Current Pollution Reports 2019Fomites are inanimate objects that become colonized with microbes and serve as potential intermediaries for transmission to/from humans. This review summarizes recent... (Review)
Review
PURPOSE OF REVIEW
Fomites are inanimate objects that become colonized with microbes and serve as potential intermediaries for transmission to/from humans. This review summarizes recent literature on fomite contamination and microbial survival in the built environment, transmission between fomites and humans, and implications for human health.
RECENT FINDINGS
Applications of molecular sequencing techniques to analyze microbial samples have increased our understanding of the microbial diversity that exists in the built environment. This growing body of research has established that microbial communities on surfaces include substantial diversity, with considerable dynamics. While many microbial taxa likely die or lay dormant, some organisms survive, including those that are potentially beneficial, benign, or pathogenic. Surface characteristics also influence microbial survival and rates of transfer to and from humans. Recent research has combined experimental data, mechanistic modeling, and epidemiological approaches to shed light on the likely contributors to microbial exchange between fomites and humans and their contributions to adverse (and even potentially beneficial) human health outcomes.
SUMMARY
In addition to concerns for fomite transmission of potential pathogens, new analytical tools have uncovered other microbial matters that can be transmitted indirectly via fomites, including entire microbial communities and antibiotic-resistant bacteria. Mathematical models and epidemiological approaches can provide insight on human health implications. However, both are subject to limitations associated with study design, and there is a need to better understand appropriate input model parameters. Fomites remain an important mechanism of transmission of many microbes, along with direct contact and short- and long-range aerosols.
PubMed: 34171005
DOI: 10.1007/s40726-019-00123-6 -
Intervirology 2018Human enteric viruses are associated with several clinical features, especially gastroenteritis. Large amounts of these viruses can be released in the environment and... (Review)
Review
Human enteric viruses are associated with several clinical features, especially gastroenteritis. Large amounts of these viruses can be released in the environment and spread to people. Enteric viruses are nonenveloped viruses and have displayed good survival in the environment. They can be significantly resistant in food and water but also on fomites, and this is thought to play a role in transmission, leading to sporadic cases or outbreaks. The survival of enteric viruses on fomites relies on many factors including the virus itself, fomite properties, and extrinsic environmental factors such as temperature or relative humidity. Several reports in the literature have found an association with gastroenteritis cases or outbreaks and fomites naturally contaminated by enteric viruses. However, the study of virus survival following natural contamination is challenging, and most published studies are laboratory based, using experimental contamination. In addition, recent and detailed data on the resistance of each of the main enteric viruses on fomites are scarce. Many approaches, both physical and chemical, can be used to inactivate enteric viruses, the efficacy of which depends on the virus and the disinfection conditions.
Topics: Disease Transmission, Infectious; Fomites; Gastroenteritis; Humans; Microbial Viability; Virus Diseases; Virus Inactivation
PubMed: 28614823
DOI: 10.1159/000448807 -
Interface Focus Apr 2022The COVID-19 pandemic is the most severe pandemic caused by a respiratory virus since the 1918 influenza pandemic. As is the case with other respiratory viruses, three... (Review)
Review
The COVID-19 pandemic is the most severe pandemic caused by a respiratory virus since the 1918 influenza pandemic. As is the case with other respiratory viruses, three modes of transmission have been invoked: contact (direct and through fomites), large droplets and aerosols. This narrative review makes the case that aerosol transmission is an important mode for COVID-19, through reviewing studies about bioaerosol physiology, detection of infectious SARS-CoV-2 in exhaled bioaerosols, prolonged SARS-CoV-2 infectivity persistence in aerosols created in the laboratory, detection of SARS-CoV-2 in air samples, investigation of outbreaks with manifest involvement of aerosols, and animal model experiments. SARS-CoV-2 joins influenza A virus as a virus with proven pandemic capacity that can be spread by the aerosol route. This has profound implications for the control of the current pandemic and for future pandemic preparedness.
PubMed: 35261731
DOI: 10.1098/rsfs.2021.0072 -
The FEBS Journal Sep 2020The newly recognised coronavirus SARS-CoV-2, causative agent of coronavirus disease (COVID-19), has caused a pandemic with huge ramifications for human interactions... (Review)
Review
The newly recognised coronavirus SARS-CoV-2, causative agent of coronavirus disease (COVID-19), has caused a pandemic with huge ramifications for human interactions around the globe. As expected, research efforts to understand the virus and curtail the disease are moving at a frantic pace alongside the spread of rumours, speculations and falsehoods. In this article, we aim to clarify the current scientific view behind several claims or controversies related to COVID-19. Starting with the origin of the virus, we then discuss the effect of ibuprofen and nicotine on the severity of the disease. We highlight the knowledge on fomites and SARS-CoV-2 and discuss the evidence and explications for a disproportionately stronger impact of COVID-19 on ethnic minorities, including a potential protective role for vitamin D. We further review what is known about the effects of SARS-CoV-2 infection in children, including their role in transmission of the disease, and conclude with the science on different mortality rates between different countries and whether this hints at the existence of more pathogenic cohorts of SARS-CoV-2.
Topics: Adult; Aged; COVID-19; Child; Evidence-Based Medicine; Female; Fomites; Humans; Ibuprofen; Male; Nicotine; Pandemics; Prejudice; Racial Groups; SARS-CoV-2; Severity of Illness Index; Vitamin D Deficiency
PubMed: 32500928
DOI: 10.1111/febs.15442 -
ACS Environmental Au Sep 2023Documenting the occurrence of viruses on fomites is crucial in determining the significance of fomite-mediated transmission and the potential use of fomites for... (Review)
Review
Documenting the occurrence of viruses on fomites is crucial in determining the significance of fomite-mediated transmission and the potential use of fomites for environmental disease surveillance. We conducted a systematic review and meta-analysis to compile information on the occurrence of human viruses on fomites in the environment; we identified 134 peer-reviewed papers. We compiled sampling and measurement methods, results, quality control information, and whether virus data were compared with community health data from the papers. We conducted univariate and multivariate analyses to investigate if presence of virus on fomites was associated with virus type (enveloped, nonenveloped), sampling location (healthcare setting, nonhealthcare temporary setting, nonhealthcare nontemporary setting), and area of fomite swabbed (<50, 50-100, >100 cm). Across 275 data sets from the 134 papers, there was the most data available for Coronaviridae and from fomites at hospitals. Positivity rates, defined as the percent positive fomite samples, were low (median = 6%). Data were available on viruses from 16 different viral families, but data on viruses from 9 families had few ( < 5) data sets. Many human virus families were not identified in this review (11 families). Less than 15% of the data sets reported virus concentrations in externally valid units (viruses per area of surface), and 16% provided a quantitative comparison between virus and health data. Virus type and area swabbed were significant predictors of virus presence on fomites, and the positivity rate of data sets collected from healthcare settings and nonhealthcare nontemporary settings (e.g., individual housing) were significantly higher than those collected in nonhealthcare temporary settings (e.g., restaurants). Data from this review indicates that viruses may be present on fomites, that fomite-mediated virus transmission may occur, and that fomites may provide information on circulation of infectious diseases in the community. However, more quantitative data on diverse viruses are needed, and method reporting needs significant improvements.
PubMed: 37743950
DOI: 10.1021/acsenvironau.3c00025