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World Journal of Gastrointestinal... Oct 2014To evaluate the risk of transmission of carbapenem-resistant Enterobacteriaceae (CRE) and their related superbugs during gastrointestinal (GI) endoscopy. Reports of... (Review)
Review
To evaluate the risk of transmission of carbapenem-resistant Enterobacteriaceae (CRE) and their related superbugs during gastrointestinal (GI) endoscopy. Reports of outbreaks linked to GI endoscopes contaminated with different types of infectious agents, including CRE and their related superbugs, were reviewed. Published during the past 30 years, both prior to and since CRE's emergence, these reports were obtained by searching the peer-reviewed medical literature (via the United States National Library of Medicine's "MEDLINE" database); the Food and Drug Administration's Manufacturer and User Facility Device Experience database, or "MAUDE"; and the Internet (via Google's search engine). This review focused on an outbreak of CRE in 2013 following the GI endoscopic procedure known as endoscopic retrograde cholangiopancreatography, or ERCP, performed at "Hospital X" located in the suburbs of Chicago (IL; United States). Part of the largest outbreak of CRE in United States history, the infection and colonization of 10 and 28 of this hospital's patients, respectively, received considerable media attention and was also investigated by the Centers for Disease Control and Prevention (CDC), which published a report about this outbreak in Morbidity and Mortality Weekly Report (MMWR), in 2014. This report, along with the results of an independent inspection of Hospital X's infection control practices following this CRE outbreak, were also reviewed. While this article focuses primarily on the prevention of transmissions of CRE and their related superbugs in the GI endoscopic setting, some of its discussion and recommendations may also apply to other healthcare settings, to other types of flexible endoscopes, and to other types of transmissible infectious agents. This review found that GI endoscopy is an important risk factor for the transmission of CRE and their related superbugs, having been recently associated with patient morbidity and mortality following ERCP. The CDC reported in MMWR that the type of GI endoscope, known as an ERCP endoscope, that Hospital X used to perform ERCP in 2013 on the 38 patients who became infected or colonized with CRE might be particularly challenging to clean and disinfect, because of the complexity of its physical design. If performed in strict accordance with the endoscope manufacturer's labeling, supplemented as needed with professional organizations' published guidelines, however, current practices for reprocessing GI endoscopes, which include high-level disinfection, are reportedly adequate for the prevention of transmission of CRE and their related superbugs. Several recommendations are provided to prevent CRE transmissions in the healthcare setting. CRE transmissions are not limited to contaminated GI endoscopes and also have been linked to other reusable flexible endoscopic instrumentation, including bronchoscopes and cystoscopes. In conclusion, contaminated GI endoscopes, particularly those used during ERCP, have been causally linked to outbreaks of CRE and their related superbugs, with associated patient morbidity and mortality. Thorough reprocessing of these complex reusable instruments is necessary to prevent disease transmission and ensure patient safety during GI endoscopy. Enhanced training and monitoring of reprocessing staffers to verify the proper cleaning and brushing of GI endoscopes, especially the area around, behind and near the forceps elevator located at the distal end of the ERCP endoscope, are recommended. If the ERCP endoscope features a narrow and exposed channel that houses a wire connecting the GI endoscope's control head to this forceps elevator, then this channel's complete reprocessing, including its flushing with a detergent using a procedure validated for effectiveness, is also emphasized.
PubMed: 25324917
DOI: 10.4253/wjge.v6.i10.457 -
ELife Feb 2021SARS-CoV-2 is difficult to contain because many transmissions occur during pre-symptomatic infection. Unlike influenza, most SARS-CoV-2-infected people do not transmit...
SARS-CoV-2 is difficult to contain because many transmissions occur during pre-symptomatic infection. Unlike influenza, most SARS-CoV-2-infected people do not transmit while a small percentage infect large numbers of people. We designed mathematical models which link observed viral loads with epidemiologic features of each virus, including distribution of transmissions attributed to each infected person and duration between symptom onset in the transmitter and secondarily infected person. We identify that people infected with SARS-CoV-2 or influenza can be highly contagious for less than 1 day, congruent with peak viral load. SARS-CoV-2 super-spreader events occur when an infected person is shedding at a very high viral load and has a high number of exposed contacts. The higher predisposition of SARS-CoV-2 toward super-spreading events cannot be attributed to additional weeks of shedding relative to influenza. Rather, a person infected with SARS-CoV-2 exposes more people within equivalent physical contact networks, likely due to aerosolization.
Topics: Aerosols; Basic Reproduction Number; COVID-19; Carrier State; China; Computer Simulation; Contact Tracing; Humans; Influenza, Human; Models, Theoretical; Pandemics; Probability; SARS-CoV-2; Time Factors; Viral Load; Virus Shedding
PubMed: 33620317
DOI: 10.7554/eLife.63537 -
International Journal of Infectious... Nov 2020The persistence and intensity of the current severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) pandemic, and the advanced planning required to balance... (Review)
Review
The persistence and intensity of the current severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) pandemic, and the advanced planning required to balance competing concerns of saving lives and avoiding economic collapse, may depend in part on whether the virus is sensitive to seasonal changes in environmental variables, such as temperature and humidity. Although multiple studies have sought to address possible effects of these variables on SARS-CoV-2 transmission, results of these studies have been varied. It is possible that at least some of the differing results are due to insufficient understanding of atmospheric science, including certain physical and chemical principles underlying selected meteorological variables, and how global seasons differ between tropical and temperate zones. The objective of this brief perspective is to provide information that may help explain some of the differing results of studies regarding the influence of environmental variables on transmissibility of SARS-CoV-2. This information may promote better variable selection and results interpretation in future studies of coronavirus disease 2019 (COVID-19) and other infectious diseases.
Topics: COVID-19; Humans; Humidity; Pandemics; SARS-CoV-2; Seasons; Weather
PubMed: 32950732
DOI: 10.1016/j.ijid.2020.09.032 -
Journal of Virology Jun 2023Although influenza A viruses of several subtypes have occasionally infected humans, to date only those of the H1, H2, and H3 subtypes have led to pandemics and become...
Although influenza A viruses of several subtypes have occasionally infected humans, to date only those of the H1, H2, and H3 subtypes have led to pandemics and become established in humans. The detection of two human infections by avian H3N8 viruses in April and May of 2022 raised pandemic concerns. Recent studies have shown the H3N8 viruses were introduced into humans from poultry, although their genesis, prevalence, and transmissibility in mammals have not been fully elucidated. Findings generated from our systematic influenza surveillance showed that this H3N8 influenza virus was first detected in chickens in July 2021 and then disseminated and became established in chickens over wider regions of China. Phylogenetic analyses revealed that the H3 HA and N8 NA were derived from avian viruses prevalent in domestic ducks in the Guangxi-Guangdong region, while all internal genes were from enzootic poultry H9N2 viruses. The novel H3N8 viruses form independent lineages in the glycoprotein gene trees, but their internal genes are mixed with those of H9N2 viruses, indicating continuous gene exchange among these viruses. Experimental infection of ferrets with three chicken H3N8 viruses showed transmission through direct contact and inefficient transmission by airborne exposure. Examination of contemporary human sera detected only very limited antibody cross-reaction to these viruses. The continuing evolution of these viruses in poultry could pose an ongoing pandemic threat. A novel H3N8 virus with demonstrated zoonotic potential has emerged and disseminated in chickens in China. It was generated by reassortment between avian H3 and N8 virus(es) and long-term enzootic H9N2 viruses present in southern China. This H3N8 virus has maintained independent H3 and N8 gene lineages but continues to exchange internal genes with other H9N2 viruses to form novel variants. Our experimental studies showed that these H3N8 viruses were transmissible in ferrets, and serological data suggest that the human population lacks effective immunological protection against it. With its wide geographical distribution and continuing evolution in chickens, other spillovers to humans can be expected and might lead to more efficient transmission in humans.
Topics: Animals; Humans; Influenza, Human; Chickens; Influenza A Virus, H3N8 Subtype; Influenza in Birds; Public Health; Influenza A Virus, H9N2 Subtype; Phylogeny; Ferrets; China; Poultry
PubMed: 37289052
DOI: 10.1128/jvi.00434-23 -
Virology Journal Nov 2011Prion diseases are transmissible neurodegenerative conditions affecting human and a wide range of animal species. The pathogenesis of prion diseases is associated with... (Review)
Review
Prion diseases are transmissible neurodegenerative conditions affecting human and a wide range of animal species. The pathogenesis of prion diseases is associated with the accumulation of aggregates of misfolded conformers of host-encoded cellular prion protein (PrPC). Animal prion diseases include scrapie of sheep and goats, bovine spongiform encephalopathy (BSE) or mad cow disease, transmissible mink encephalopathy, feline spongiform encephalopathy, exotic ungulate spongiform encephalopathy, chronic wasting disease of cervids and spongiform encephalopathy of primates. Although some cases of sporadic atypical scrapie and BSE have also been reported, animal prion diseases have basically occurred via the acquisition of infection from contaminated feed or via the exposure to contaminated environment. Scrapie and chronic wasting disease are naturally sustaining epidemics. The transmission of BSE to human has caused more than 200 cases of variant Cruetzfeldt-Jacob disease and has raised serious public health concerns. The present review discusses the epidemiology, clinical neuropathology, transmissibility and genetics of animal prion diseases.
Topics: Animals; Cats; Cattle; Goats; Mink; Primates; Prion Diseases; Sheep
PubMed: 22044871
DOI: 10.1186/1743-422X-8-493 -
PloS One 2022In a viral epidemic, the emergence of a novel strain with increased transmissibility (larger value of basic reproduction number R0) sparks the fear that the increase in...
In a viral epidemic, the emergence of a novel strain with increased transmissibility (larger value of basic reproduction number R0) sparks the fear that the increase in transmissibility is likely to lead to an increase in disease severity. It is required to investigate if a new, more contagious strain will be necessarily dominant in the population and resulting in more disease severity. In this paper, the impact of the asymptomatic transmission and the emergence time of a more transmissible variant of a multi-strain viral disease on the disease prevalence, disease severity, and the dominant variant in an epidemic was investigated by a proposed 2-strain epidemic model. The simulation results showed that considering only R0, is insufficient to predict the outcome of a new, more contagious strain in the population. A more transmissible strain with a high fraction of asymptomatic cases can substantially reduce the mortality rate. If the emergence time of the new strain is closer to the start of the epidemic, the new, more contagious variant has more chance to win the viral competition and be the dominant strain; otherwise, despite being more contagious, it cannot dominate previous strains. In conclusion, three factors of R0, the fraction of asymptomatic transmission, and the emergence time of the new strain are required to correctly determine the prevalence, disease severity, and the winner of the viral competition.
Topics: Basic Reproduction Number; Epidemics; Humans; Influenza, Human; Severity of Illness Index; Virus Diseases
PubMed: 36206212
DOI: 10.1371/journal.pone.0269464 -
MedRxiv : the Preprint Server For... Mar 2020The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is straining health systems around the world. Although the Chinese...
BACKGROUND
The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is straining health systems around the world. Although the Chinese government implemented a number of severe restrictions on people's movement in an attempt to contain its local and international spread, the virus had already reached many areas of the world in part due to its potent transmissibility and the fact that a substantial fraction of infected individuals develop little or no symptoms at all. Following its emergence, the virus started to generate sustained transmission in neighboring countries in Asia, Western Europe, Australia, Canada and the United States, and finally in South America and Africa. As the virus continues its global spread, a clear and evidence-based understanding of properties and dynamics of the global transmission network of SARS-CoV-2 is essential to design and put in place efficient and globally coordinated interventions.
METHODS
We employ molecular surveillance data of SARS-CoV-2 epidemics for inference and comprehensive analysis of its global transmission network before the pandemic declaration. Our goal was to characterize the spatial-temporal transmission pathways that led to the establishment of the pandemic. We exploited a network-based approach specifically tailored to emerging outbreak settings. Specifically, it traces the accumulation of mutations in viral genomic variants via mutation trees, which are then used to infer transmission networks, revealing an up-to-date picture of the spread of SARS-CoV-2 between and within countries and geographic regions.
RESULTS AND CONCLUSIONS
The analysis suggest multiple introductions of SARS-CoV-2 into the majority of world regions by means of heterogeneous transmission pathways. The transmission network is scale-free, with a few genomic variants responsible for the majority of possible transmissions. The network structure is in line with the available temporal information represented by sample collection times and suggest the expected sampling time difference of few days between potential transmission pairs. The inferred network structural properties, transmission clusters and pathways and virus introduction routes emphasize the extent of the global epidemiological linkage and demonstrate the importance of internationally coordinated public health measures.
PubMed: 32511620
DOI: 10.1101/2020.03.22.20041145 -
Journal of Epidemiology Feb 2022A measles outbreak involving 60 cases occurred in Yamagata, Japan in 2017. Using two different mathematical models for different datasets, we aimed to estimate measles...
BACKGROUND
A measles outbreak involving 60 cases occurred in Yamagata, Japan in 2017. Using two different mathematical models for different datasets, we aimed to estimate measles transmissibility over time and explore any heterogeneous transmission patterns.
METHODS
The first model relied on the temporal distribution for date of illness onset for cases, and a generation-dependent model was applied to the data. Another model focused on the transmission network. Using the illness-onset date along with the serial interval and geographical location of exposure, we reconstructed a transmission network with 19 unknown links. We then compared the number of secondary transmissions with and without clinical symptoms or laboratory findings.
RESULTS
Using a generation-dependent model (assuming three generations other than the index case), the reproduction number (R) over generations 0, 1, and 2 were 25.3, 1.3, and <0.1, respectively, explicitly yielding the transmissibility over each generation. The network data enabled us to demonstrate that both the mean and the variance for the number of secondary transmissions per primary case declined over time. Comparing primary cases with and without secondary transmission, high viral shedding was the only significant determinant (P < 0.01).
CONCLUSIONS
The R declined abruptly over subsequent generations. Use of network data revealed the distribution of the number of secondary transmissions per primary case and also allowed us to identify possible secondary transmission risk factors. High viral shedding from the throat mucosa was identified as a potential predictor of secondary transmission.
Topics: Disease Outbreaks; Humans; Japan; Measles; Models, Theoretical; Risk Factors
PubMed: 33281152
DOI: 10.2188/jea.JE20200455 -
PloS One 2018Effective public health research and preparedness requires an accurate understanding of which virus species possess or are at risk of developing human transmissibility....
Effective public health research and preparedness requires an accurate understanding of which virus species possess or are at risk of developing human transmissibility. Unfortunately, our ability to identify these viruses is limited by gaps in disease surveillance and an incomplete understanding of the process of viral adaptation. By fitting boosted regression trees to data on 224 human viruses and their associated traits, we developed a model that predicts the human transmission ability of zoonotic viruses with over 84% accuracy. This model identifies several viruses that may have an undocumented capacity for transmission between humans. Viral traits that predicted human transmissibility included infection of nonhuman primates, the absence of a lipid envelope, and detection in the human nervous system and respiratory tract. This predictive model can be used to prioritize high-risk viruses for future research and surveillance, and could inform an integrated early warning system for emerging infectious diseases.
Topics: Animals; Communicable Diseases, Emerging; Epidemiological Monitoring; Humans; Machine Learning; Models, Biological; Public Health; Virus Diseases; Viruses; Zoonoses
PubMed: 30403733
DOI: 10.1371/journal.pone.0206926 -
Journal of Virology Nov 2017Two subtypes of influenza A virus (IAV), avian-origin canine influenza virus (CIV) H3N2 (CIV-H3N2) and equine-origin CIV H3N8 (CIV-H3N8), are enzootic in the canine...
Two subtypes of influenza A virus (IAV), avian-origin canine influenza virus (CIV) H3N2 (CIV-H3N2) and equine-origin CIV H3N8 (CIV-H3N8), are enzootic in the canine population. Dogs have been demonstrated to seroconvert in response to diverse IAVs, and naturally occurring reassortants of CIV-H3N2 and the 2009 H1N1 pandemic virus (pdmH1N1) have been isolated. We conducted a thorough phenotypic evaluation of CIV-H3N2 in order to assess its threat to human health. Using ferret-generated antiserum, we determined that CIV-H3N2 is antigenically distinct from contemporary human H3N2 IAVs, suggesting that there may be minimal herd immunity in humans. We assessed the public health risk of CIV-H3N2 × pandemic H1N1 (pdmH1N1) reassortants by characterizing their genetic compatibility and pathogenicity and transmissibility. Using a luciferase minigenome assay, we quantified the polymerase activity of all possible 16 ribonucleoprotein (RNP) complexes (PB2, PB1, PA, NP) between CIV-H3N2 and pdmH1N1, identifying some combinations that were more active than either parental virus complex. Using reverse genetics and fixing the CIV-H3N2 hemagglutinin (HA), we found that 51 of the 127 possible reassortant viruses were viable and able to be rescued. Nineteen of these reassortant viruses had high-growth phenotypes , and 13 of these replicated in mouse lungs. A single reassortant with the NP and HA gene segments from CIV-H3N2 was selected for characterization in ferrets. The reassortant was efficiently transmitted by contact but not by the airborne route and was pathogenic in ferrets. Our results suggest that CIV-H3N2 reassortants may pose a moderate risk to public health and that the canine host should be monitored for emerging IAVs. IAV pandemics are caused by the introduction of novel viruses that are capable of efficient and sustained transmission into a human population with limited herd immunity. Dogs are a a potential mixing vessel for avian and mammalian IAVs and represent a human health concern due to their susceptibility to infection, large global population, and close physical contact with humans. Our results suggest that humans are likely to have limited preexisting immunity to CIV-H3N2 and that CIV-H3N2 × pdmH1N1 reassortants have moderate genetic compatibility and are transmissible by direct contact in ferrets. Our study contributes to the increasing evidence that surveillance of the canine population for IAVs is an important component of pandemic preparedness.
Topics: Animals; Dog Diseases; Dogs; Female; Ferrets; Influenza A Virus, H1N1 Subtype; Influenza A Virus, H3N2 Subtype; Lung; Madin Darby Canine Kidney Cells; Mice; Mice, Inbred BALB C; Orthomyxoviridae Infections; Reassortant Viruses; Risk Factors; Viral Proteins; Zoonoses
PubMed: 28814512
DOI: 10.1128/JVI.00637-17