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Trends in Immunology Dec 2020The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) marks the third highly pathogenic coronavirus to spill over into the human population.... (Review)
Review
The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) marks the third highly pathogenic coronavirus to spill over into the human population. SARS-CoV-2 is highly transmissible with a broad tissue tropism that is likely perpetuating the pandemic. However, important questions remain regarding its transmissibility and pathogenesis. In this review, we summarize current SARS-CoV-2 research, with an emphasis on transmission, tissue tropism, viral pathogenesis, and immune antagonism. We further present advances in animal models that are important for understanding the pathogenesis of SARS-CoV-2, vaccine development, and therapeutic testing. When necessary, comparisons are made from studies with SARS to provide further perspectives on coronavirus infectious disease 2019 (COVID-19), as well as draw inferences for future investigations.
Topics: Animals; COVID-19; Humans; SARS-CoV-2
PubMed: 33132005
DOI: 10.1016/j.it.2020.10.004 -
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 -
Turkish Journal of Medical Sciences Apr 2020Along the centuries, novel strain of virus such as influenza produces pandemics which increase illness, death and disruption in the countries. Spanish flu in 1918, Asian... (Review)
Review
Along the centuries, novel strain of virus such as influenza produces pandemics which increase illness, death and disruption in the countries. Spanish flu in 1918, Asian flu in 1957, Hong Kong flu in 1968 and swine flu in 2009 were known pandemic which had various characteristics in terms of morbidity and mortality. A current pandemic is caused by novel corona virus originated from China. COVID-19 pandemic is very similar to Spanish, Hong Kong, Asian and swine influenza pandemics in terms of spreading to world by the mobilized people. Burden of pandemic is considered in terms of disease transmissibility and the growth rate of epidemic and duration of pandemic can be calculated by transmissibility characteristic. The case definition, finding out cases and first case cluster, proper treatment, sufficient stockpiles of medicine and population cooperation with the containment strategy should be considered for reduction of burden of pandemic.
Topics: Basic Reproduction Number; Betacoronavirus; COVID-19; Coronavirus Infections; History, 20th Century; History, 21st Century; Humans; Influenza Pandemic, 1918-1919; Influenza, Human; Pandemics; Pneumonia, Viral; SARS-CoV-2; Turkey
PubMed: 32299204
DOI: 10.3906/sag-2004-133 -
Clinical Microbiology Reviews Dec 2020The Gram-negative bacterium is responsible for deadly plague, a zoonotic disease established in stable foci in the Americas, Africa, and Eurasia. Its persistence in the... (Review)
Review
The Gram-negative bacterium is responsible for deadly plague, a zoonotic disease established in stable foci in the Americas, Africa, and Eurasia. Its persistence in the environment relies on the subtle balance between -contaminated soils, burrowing and nonburrowing mammals exhibiting variable degrees of plague susceptibility, and their associated fleas. Transmission from one host to another relies mainly on infected flea bites, inducing typical painful, enlarged lymph nodes referred to as buboes, followed by septicemic dissemination of the pathogen. In contrast, droplet inhalation after close contact with infected mammals induces primary pneumonic plague. Finally, the rarely reported consumption of contaminated raw meat causes pharyngeal and gastrointestinal plague. Point-of-care diagnosis, early antibiotic treatment, and confinement measures contribute to outbreak control despite residual mortality. Mandatory primary prevention relies on the active surveillance of established plague foci and ectoparasite control. Plague is acknowledged to have infected human populations for at least 5,000 years in Eurasia. genomes recovered from affected archaeological sites have suggested clonal evolution from a common ancestor shared with the closely related enteric pathogen and have indicated that gene acquisition during the Bronze Age conferred with ectoparasite transmissibility while maintaining its enteric transmissibility. Three historic pandemics, starting in 541 AD and continuing until today, have been described. At present, the third pandemic has become largely quiescent, with hundreds of human cases being reported mainly in a few impoverished African countries, where zoonotic plague is mostly transmitted to people by rodent-associated flea bites.
Topics: Animals; Archaeology; Clonal Evolution; Humans; Insect Vectors; Phylogeny; Plague; Population Surveillance; Rodentia; Siphonaptera; Soil Microbiology; Yersinia pestis
PubMed: 33298527
DOI: 10.1128/CMR.00044-19 -
Acta Medica Portuguesa Dec 2019Over the last few decades, behavioral changes in sexual practices have made oral transmission of traditional sexually transmissible infections increasingly recognized.... (Review)
Review
Over the last few decades, behavioral changes in sexual practices have made oral transmission of traditional sexually transmissible infections increasingly recognized. Patients harboring a sexually transmissible infection may first present lesions on the oral cavity, as these may be visible and interfere with basic functions such as speech or swallowing. Moreover, the oral cavity may function as a reservoir for future spread of these infections. In order to successfully control this problem, a greater focus on oral sex should be persued, along with promotion of the use of condom and education on safe oral sex practices. Furthermore, examination of the oral cavity should is essential when evaluating any patient suspected of harboring a sexually transmissible infection. In this article, oral transmission of several viral and bacterial infections is reviewed, including human papillomavirus infection, genital herpes, syphilis and gonorrhea, among others.
Topics: Chlamydia Infections; Chlamydia trachomatis; Gonorrhea; HIV Infections; Herpes Simplex; Humans; Mouth Diseases; Papillomavirus Infections; Safe Sex; Sexual Behavior; Sexually Transmitted Diseases; Syphilis
PubMed: 31851887
DOI: 10.20344/amp.12191 -
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 -
Frontiers in Immunology 2021Breastfeeding not only provides the optimum source of nutrients for the neonate and its first strong shield against infection but also lays the foundation for somatic... (Meta-Analysis)
Meta-Analysis
Breastfeeding not only provides the optimum source of nutrients for the neonate and its first strong shield against infection but also lays the foundation for somatic and psychological bonding between the mother and child. During the current COVID-19 pandemic, although the guidelines of the relevant international and national agencies recommend breastfeeding by SARS-CoV-2-infected mothers, considerable insecurity persists in daily clinical practice regarding the safety of the infants and the perceived advantages and disadvantages of discontinuation of breastfeeding. This is a systematic review of the currently available information regarding the transmissibility of SARS-CoV-2 through or while breastfeeding and the protection against infection that breast milk might provide. The accumulated body of knowledge regarding the role of breast milk in the development of the neonatal immune system and protection against infection by other respiratory viruses is discussed, with a focus on the anti-inflammatory role of the antibodies, microbes, and viruses provided to the infant in breast milk and its relevance to the case of SARS-CoV-2.
Topics: Antibodies, Viral; Breast Feeding; COVID-19; Female; Humans; Infant, Newborn; Infectious Disease Transmission, Vertical; Milk, Human; Pregnancy; Pregnancy Complications, Infectious; SARS-CoV-2
PubMed: 33897707
DOI: 10.3389/fimmu.2021.661806 -
European Journal of Medical Research Jan 2021Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), belonging to the Coronaviridae family, is agent of 2019 novel coronavirus disease (COVID-19). COVID-19... (Meta-Analysis)
Meta-Analysis
BACKGROUND AND AIMS
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), belonging to the Coronaviridae family, is agent of 2019 novel coronavirus disease (COVID-19). COVID-19 emerged in Wuhan, Hubei province of China, in early December 2019 and is now considered a pandemic. This study aimed to investigate the airborne transmission of COVID-19 and the role of face mask to prevent it.
METHODS
A systematic search for English-language literature was done via PUBMED/Medline and Google Scholar up to October 2020. There was two search strategy; for airborne transmission and the role of face mask for prevention of SARS-CoV-2 infection. Based on a fixed and random effects model, the RR and 95% CI were used to evaluate the combined risk. This meta-analysis followed Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) Guidelines.
RESULTS
After eligibility assessment, four articles with a total of 7688 participants were included in this meta-analysis. The result of this meta-analysis has shown significant reduction in infection with face mask use; the pooled RR (95%CI) was 0.12 [0.06, 0.27] (P < 0.001).
CONCLUSION
In conclusion, this meta-analysis suggests that there is association between face mask use and reduction of COVID-19. However, COVID-19 spreads primarily with contact routes and respiratory droplets, but its transmissibility has many mysteries yet and there is controversy about airborne transmission of COVID-19.
Topics: COVID-19; Humans; Masks; SARS-CoV-2
PubMed: 33388089
DOI: 10.1186/s40001-020-00475-6 -
The Journal of Hospital Infection Mar 2020Currently, the emergence of a novel human coronavirus, SARS-CoV-2, has become a global health concern causing severe respiratory tract infections in humans.... (Review)
Review
Currently, the emergence of a novel human coronavirus, SARS-CoV-2, has become a global health concern causing severe respiratory tract infections in humans. Human-to-human transmissions have been described with incubation times between 2-10 days, facilitating its spread via droplets, contaminated hands or surfaces. We therefore reviewed the literature on all available information about the persistence of human and veterinary coronaviruses on inanimate surfaces as well as inactivation strategies with biocidal agents used for chemical disinfection, e.g. in healthcare facilities. The analysis of 22 studies reveals that human coronaviruses such as Severe Acute Respiratory Syndrome (SARS) coronavirus, Middle East Respiratory Syndrome (MERS) coronavirus or endemic human coronaviruses (HCoV) can persist on inanimate surfaces like metal, glass or plastic for up to 9 days, but can be efficiently inactivated by surface disinfection procedures with 62-71% ethanol, 0.5% hydrogen peroxide or 0.1% sodium hypochlorite within 1 minute. Other biocidal agents such as 0.05-0.2% benzalkonium chloride or 0.02% chlorhexidine digluconate are less effective. As no specific therapies are available for SARS-CoV-2, early containment and prevention of further spread will be crucial to stop the ongoing outbreak and to control this novel infectious thread.
Topics: Betacoronavirus; COVID-19; Coronavirus Infections; Disinfectants; Environmental Microbiology; Humans; Microbial Viability; Pneumonia, Viral; SARS-CoV-2
PubMed: 32035997
DOI: 10.1016/j.jhin.2020.01.022 -
Cell Sep 2020Infectious diseases prevalent in humans and animals are caused by pathogens that once emerged from other animal hosts. In addition to these established infections, new... (Review)
Review
Infectious diseases prevalent in humans and animals are caused by pathogens that once emerged from other animal hosts. In addition to these established infections, new infectious diseases periodically emerge. In extreme cases they may cause pandemics such as COVID-19; in other cases, dead-end infections or smaller epidemics result. Established diseases may also re-emerge, for example by extending geographically or by becoming more transmissible or more pathogenic. Disease emergence reflects dynamic balances and imbalances, within complex globally distributed ecosystems comprising humans, animals, pathogens, and the environment. Understanding these variables is a necessary step in controlling future devastating disease emergences.
Topics: COVID-19; Communicable Diseases, Emerging; Coronavirus Infections; Demography; Environment; Host-Pathogen Interactions; Humans; Pandemics; Pneumonia, Viral
PubMed: 32846157
DOI: 10.1016/j.cell.2020.08.021