Severe acute respiratory syndrome: an update

Comparison of Selected Characteristics of SARS-CoV-2, SARS-CoV, and HCoV-NL63

The global pandemic known as coronavirus disease 2019 (COVID-19) was caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This review article presents the taxonomy of SARS-CoV-2 coronaviruses, which have been classified as the seventh known human pathogenic coronavirus. The etiology of COVID-19 is also briefly discussed. Selected characteristics of SARS-CoV-2, SARS-CoV, and HCoV-NL63 are compared in the article. The angiotensin converting enzyme-2 (ACE-2) has been identified as the receptor for the SARS-CoV-2 viral entry. ACE2 is well-known as a counter-regulator of the renin-angiotensin system (RAAS) and plays a key role in the cardiovascular system. In the therapy of patients with COVID-19, there has been a concern about the use of RAAS inhibitors. As a result, it is hypothesized that ACE inhibitors do not directly affect ACE2 activity in clinical use. Coronaviruses are zoonotic RNA viruses. Identification of the primary causative agent of the SARS-CoV-2 is essential. Sequencing showed that the genome of the Bat CoVRaTG13 virus found in bats matches the genome of up to (96.2%) of SARS-CoV-2 virus. Sufficient knowledge of the molecular and biological mechanisms along with reliable information related to SARS-CoV-2 gives hope for a quick solution to epidemiological questions and therapeutic processes.

Influence of age and gender on the epidemic of COVID-19 : Evidence from 177 countries and territories-an exploratory, ecological study

BACKGROUND

The pandemic of coronavirus disease 2019 (COVID-19) is spreading worldwide with an uncertain ultimate impact on every aspect of human society. Recognizing the groups with higher susceptibility and fatality are in urgent need.

METHODS

We retrieved the total number of confirmed incident and death cases of COVID-19 in 177 countries/territories from the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU). Data of age and gender composition were collected from the United Nations Department of Economic and Social Affairs. Spearman's correlation analysis was used to explore the association between the composition of age and gender and the incidence rate (IRC), case fatality rate (CFRC), and mortality rate of COVID-19 (MRC). Multiple comparisons were adjusted by the Bonferroni method, and the threshold p-value was set as p < 0.01. Software SPSS 23.0, ArcGIS 10.6, and GraphPad Prism 8.0 were used to generate our results.

RESULTS

Median age was positively correlated to IRC, CFRC and MRC (r_s = 0.60; r_s = 0.27; r_s = 0.61, p < 0.0001 for all). The age-dependent correlation between people over 65 years of age with IRC was higher in females, while the correlation between age distribution and CFRC as well as MRC was higher in males (p < 0.0001 for all). Besides, we found the age-gender-dependent differences were correlated to IRC in places with high income and associated with CFRC in non-high income countries/territories.

CONCLUSION

The correlation between the composition of age and gender and the epidemic characteristics of COVID-19 confirmed previous points that females are more susceptible to COVID-19. The results remind us that more attention should be paid to male patients, particularly those over 65 years old for enhanced clinical management.

Travelers as a sentinel population: use of sentinel networks to inform pretravel and posttravel evaluation

The establishment of collaborative sentinel surveillance networks specifically to monitor disease trends among travelers offers new options for evaluating travel health issues. These networks can inform pre- and posttravel patient management by providing complementary surveillance information, facilitating communication and collaboration between participating network sites, and enabling new analytical options for travel-related research. The two major multinational sentinel networks are TropNetEurop and GeoSentinel. Practical examples demonstrating their significant contributions to improved travel health information are discussed. Data obtained from studying health problems among travelers may also have significant benefits for local populations in resource-limited countries. However, there are limitations of data collected by sentinel networks, so they should be considered as complementary tools and not relied on as an exclusive basis for evaluating health risks among travelers.

Severe acute respiratory syndrome (SARS)

This article reviews the virology, history, pathology, epidemiology, clinical presentations, complications, radiology, laboratory testing, diagnosis, treatment, and prevention of severe respiratory distress syndrome, with reference to documented outbreaks of the disease.

Risques d’importation des maladies infectieuses exotiques en France métropolitaine : détection, alerte et réponse

Dans le domaine des maladies infectieuses, l’Institut de veille sanitaire est chargé d’impulser et de coordonner l’anticipation et l’analyse des risques infectieux afin d’alerter l’autorité sanitaire et de lui fournir des éléments de réponse face à ces risques. Dans le domaine infectieux, la veille épidémiologique vise à détecter précocement les menaces sanitaires en captant des signaux d’alerte qui recouvrent les champs humain et animal. Les signaux étant nombreux et de qualité variable, une vérification est effectuée. L’évaluation du risque d’introduction et de diffusion d’un pathogène sur le territoire est ensuite effectuée au travers d’une expertise multidisciplinaire. Dans cet article nous illustrons à l’aide d’exemples, différents scenarii de détection, d’analyse de risque et de réponse concernant des phénomènes infectieux présents dans la zone intertropicale et potentiellement importables en France métropolitaine. Qu’il s’agisse d’agents peu connus car rarement identifiés en Métropole, ou d’agents émergents de novo, l’analyse et la réponse doivent rester flexibles et être ajustées en fonction des données épidémiologiques et de l’interaction entre l’agent, l’hôte et son environnement. Ces incertitudes nous amèneront à discuter des besoins en matière de surveillance, dans une optique d’amélioration de la réactivité et de l’expertise.

A line immunoassay utilizing recombinant nucleocapsid proteins for detection of antibodies to human coronaviruses

Most coronaviruses infecting humans cause mild diseases, whereas severe acute respiratory syndrome (SARS)-associated coronavirus is an extremely dangerous pathogen. Here, we report the development of a serologic assay for detection of antibodies to human coronaviruses (HCoVs) based on recombinant nucleocapsid (N) proteins of all known pathogenic strains (229E, NL63, OC43, HKU1, SARS). The novel immunoassay is highly useful for epidemiologic surveys, where use of nucleic acid diagnostics often is limited. Purified recombinant antigens were immobilized on nitrocellulose membranes and applied in a line immunoassay, which allows rapid detection of antibodies to 5 different HCoVs in a single experiment. For assay evaluation, serum samples from persons infected with 229E or OC43 (acute/convalescent), recovered SARS patients and healthy donors were analyzed. Screening for nucleocapsid (N)-specific immunoglobulin G (IgG) in convalescent sera reached 100% sensitivity. With this new technique, we found that recently identified NL63 and HKU1 contribute significantly to the overall spectrum of coronavirus infections. Possibly, cross-reactive antibody responses were observed using 229E and OC43 serum pairs. However, the potential of this assay could clearly be demonstrated employing SARS-positive serum samples, where nonspecific binding to nucleocapsids of other HCoVs was not observed. This coronavirus strain-specific line immunoassay represents a powerful tool for serologic diagnostics.

SARS molecular epidemiology: a Chinese fairy tale of controlling an emerging zoonotic disease in the genomics era

Severe acute respiratory syndrome (SARS) was the first natural disaster that challenged the Chinese people at the beginning of the twenty-first century. It was caused by a novel animal coronavirus, never recognized or characterized before. This SARS coronavirus (SARS-CoV) exploited opportunities provided by 'wet markets' in southern China to adapt to the palm civet and human. Under the positive selection pressure of human host, certain mutated lineages of the virus became readily transmissible between humans and thus caused the epidemic of 2002-2003. This review will provide first-hand information, particularly from Guangdong, China, about the initial epidemiology, the identification of the aetiological agent of the disease, the molecular evolution study of the virus, the finding of SARS-like CoV in horseshoe bats and the mechanistic analysis for the cross-host tropism transition. The substantial scientific contributions made by the Chinese scientists towards understanding the virus and the disease will be emphasized. Along with the description of the scientific discoveries and analyses, the significant impact of these researches upon the public health measurement or regulations will be highlighted. It is aimed to appreciate the concerted and coordinated global response that controlled SARS within a short period of time as well as the research strategy and methodology developed along with this process, which can be applied in response to other public health challenges, particularly the future emerging/re-merging infectious diseases.

Progress in the discovery and definition of monoclonal antibodies for use in feline research

The practice of veterinary medicine and research into both animal diseases and animal models of human disease are restricted by the scarcity of monoclonal antibodies (mAb) that react with animal proteins. One way to enlarge the repertoire of mAb to animal leukocyte differentiation antigens (LDA) is to test mAb specific to other species for cross-reactivity to the species of interest. We have tested a panel of 380 commercially available anti-human mAb for cross-reactivity to feline LDA. Twenty-six of these mAb cross-react with cat LDA and 19 others are of questionable cross-reactivity. Definition of mAb specificity in the cat is being investigated by multi-color flow cytometry (FCM) to compare test mAb specificity with that of mAb to known feline LDA. The addition of these cross-reactive mAb to the anti-feline mAb currently available will enhance studies in comparative medicine.

The relationship of severe acute respiratory syndrome coronavirus with avian and other coronaviruses

In February 2003, a severe acute respiratory syndrome coronavirus (SARS-CoV) emerged in humans in Guangdong Province, China, and caused an epidemic that had severe impact on public health, travel, and economic trade. Coronaviruses are worldwide in distribution, highly infectious, and extremely difficult to control because they have extensive genetic diversity, a short generation time, and a high mutation rate. They can cause respiratory, enteric, and in some cases hepatic and neurological diseases in a wide variety of animals and humans. An enormous, previously unrecognized reservoir of coronaviruses exists among animals. Because coronaviruses have been shown, both experimentally and in nature, to undergo genetic mutations and recombination at a rate similar to that of influenza viruses, it is not surprising that zoonosis and host switching that leads to epidemic diseases have occurred among coronaviruses. Analysis of coronavirus genomic sequence data indicates that SARS-CoV emerged from an animal reservoir. Scientists examining coronavirus isolates from a variety of animals in and around Guangdong Province reported that SARS-CoV has similarities with many different coronaviruses including avian coronaviruses and SARS-CoV-like viruses from a variety of mammals found in live-animal markets. Although a SARS-like coronavirus isolated from a bat is thought to be the progenitor of SARS-CoV, a lack of genomic sequences for the animal coronaviruses has prevented elucidation of the true origin of SARS-CoV. Sequence analysis of SARS-CoV shows that the 5' polymerase gene has a mammalian ancestry; whereas the 3' end structural genes (excluding the spike glycoprotein) have an avian origin. Spike glycoprotein, the host cell attachment viral surface protein, was shown to be a mosaic of feline coronavirus and avian coronavirus sequences resulting from a recombination event. Based on phylogenetic analysis designed to elucidate evolutionary links among viruses, SARS-CoV is believed to have branched from the modern Group 2 coronaviruses, suggesting that it evolved relatively rapidly. This is significant because SARS-CoV is likely still circulating in an animal reservoir (or reservoirs) and has the potential to quickly emerge and cause a new epidemic.

When is quarantine a useful control strategy for emerging infectious diseases?

The isolation and treatment of symptomatic individuals, coupled with the quarantining of individuals that have a high risk of having been infected, constitute two commonly used epidemic control measures. Although isolation is probably always a desirable public health measure, quarantine is more controversial. Mass quarantine can inflict significant social, psychological, and economic costs without resulting in the detection of many infected individuals. The authors use probabilistic models to determine the conditions under which quarantine is expected to be useful. Results demonstrate that the number of infections averted (per initially infected individual) through the use of quarantine is expected to be very low provided that isolation is effective, but it increases abruptly and at an accelerating rate as the effectiveness of isolation diminishes. When isolation is ineffective, the use of quarantine will be most beneficial when there is significant asymptomatic transmission and if the asymptomatic period is neither very long nor very short.

Emerging viral infections in transplant recipients

PURPOSE OF REVIEW

Transplant patients are uniquely predisposed to emerging infections for a number of reasons. Two outbreaks, West Nile virus and severe acute respiratory syndrome, have recently provided important lessons on how transplant patients are affected, and how transplant programmes must adapt and evolve in the face of emerging infections. An update of emerging infections in transplant patients, using West Nile virus and severe acute respiratory syndrome as specific examples, is summarized here.

RECENT FINDINGS

Exogenous immunosuppression, specific allograft factors, and extensive contact with the healthcare system all predispose transplant patients to emerging infections. Transplant patients may acquire West Nile virus through blood transfusion, donor transmission, or community exposure. Seroprevalence data in transplant populations suggest the risk of severe neurological disease is several fold higher in transplant recipients who acquire West Nile virus compared with immunocompetent individuals. Prevention strategies are critical in this population. These include nucleic acid testing of blood products and potentially also screening organ donors in a similar manner. During the outbreak of severe acute respiratory syndrome, transplant patients with severe and rapidly progressive disease were reported. Higher viral burdens appeared to be present in transplant patients and may have implications for the increased infectivity of these patients. Transplant programmes in severe acute respiratory syndrome areas were also adversely affected because of donor concerns, recipient issues and resource problems.

SUMMARY

Transplant patients are uniquely predisposed to emerging infections. Lessons learned from West Nile virus and severe acute respiratory syndrome in transplantation should be applicable to future outbreaks of other emerging infectious diseases.

A review of vaccine research and development: human acute respiratory infections

Worldwide, acute respiratory infections (ARIs) constitute the leading cause of acute illnesses, being responsible for nearly 4 million deaths every year, mostly in young children and infants in developing countries. The main infectious agents responsible for ARIs include influenza virus, respiratory syncytial virus (RSV), parainfluenza virus type 3 (PIV-3), Streptococcus pneumoniae and Haemophilus influenzae. While effective vaccines against influenza, H. influenzae type b (Hib) and S. pneumoniae infections have been available for several years, no vaccine is available at present against illnesses caused by RSV, PIV-3, metapneumovirus or any of the three novel coronaviruses. In addition, the threat constituted by the multiple outbreaks of avian influenza during the last few years is urgently calling for the development of new influenza vaccines with broader spectrum of efficacy, which could provide immunity against an avian influenza virus pandemic. This article reviews the state of the art in vaccine R&D against ARIs and attempts to address these basic public health questions.

Progressive and nonresolving pneumonia

PURPOSE OF REVIEW

Patients with progressive and/or nonresolving community-acquired pneumonia are at risk for increased morbidity and mortality. It is critical to be able to identify patients at risk to institute early appropriate therapy. The purpose of this review is to summarise the most updated developments in this area.

RECENT FINDINGS

This review will glean from the recent literature clinical, laboratory, and radiologic findings that help identify patients at risk for such complications of their pneumonia. New studies will be reviewed that have identified some of the causes for treatment failures including the type of pathogen and discordant antimicrobial therapy. It will also discuss newly recognised and emerging infectious diseases that may result in progressive or nonresponding pneumonia including severe acute respiratory syndrome, avian influenzae, severe group A streptococcal disease, and community-acquired methicillin-resistant Staphylococcus aureus. Promising treatments have been identified for patients with progressive pneumonia due to an overwhelming host immune response including activated protein C and intravenous immunoglobulin.

SUMMARY

Both progressive and nonresolving pneumonia represent treatment failure as a result of inappropriate initial therapy, a noninfectious cause, or an overwhelming immune response. It is critical to be able to identify patients with nonresponding pneumonia and to identify patients at risk for progressive pneumonia to institute appropriate therapy.

Severe acute respiratory syndrome: responses of the healthcare system to a global epidemic

PURPOSE OF REVIEW

To evaluate recent developments in the response of the healthcare system to the threat of severe acute respiratory syndrome in the context of the Toronto experience.

RECENT FINDINGS

The severe acute respiratory syndrome outbreak affected over 8000 people killing 774 by July 2003. It particularly affected those providing health care. The initial response of the healthcare system was to use infection control techniques to prevent transmission to staff and patients. This had a dramatic impact on healthcare provision for non-severe acute respiratory syndrome patients during this period.

SUMMARY

The ongoing response to severe acute respiratory syndrome is continued effective infection control education, development of local and global policies for reacting to a severe acute respiratory syndrome-like outbreak in the future, and continued work on a vaccine for severe acute respiratory syndrome.

Newer respiratory virus infections: human metapneumovirus, avian influenza virus, and human coronaviruses

PURPOSE OF REVIEW

Recently, several previously unrecognized respiratory viral pathogens have been identified and several influenza A virus subtypes, previously known to infect poultry and wild birds, were transmitted to humans. Here we review the recent literature on these respiratory viruses.

RECENT FINDINGS

Human metapneumovirus has now been detected worldwide, causing severe respiratory tract illnesses primarily in very young, elderly and immunocompromised individuals. Animal models and reverse genetic techniques were designed for human metapneumovirus, and the first vaccine candidates have been developed. Considerable genetic and antigenic diversity was observed for human metapneumovirus, but the implication of this diversity for vaccine development and virus epidemiology requires further study. Two previously unrecognized human coronaviruses were discovered in 2004 in The Netherlands and Hong Kong. Their clinical impact and epidemiology are largely unknown and warrant further investigation. Several influenza A virus subtypes were transmitted from birds to humans, and these viruses continue to constitute a pandemic threat. The clinical symptoms associated with these zoonotic transmissions range from mild respiratory illnesses and conjunctivitis to pneumonia and acute respiratory distress syndrome, sometimes resulting in death. More basic research into virus ecology and evolution and development of effective vaccines and antiviral strategies are required to limit the impact of influenza A virus zoonoses and the threat of an influenza pandemic.

SUMMARY

Previously unknown and emerging respiratory viruses are an important threat to human health. Development of virus diagnostic tests, antiviral strategies, and vaccines for each of these pathogens is crucial to limit their impact.

Severe acute respiratory syndrome

Severe acute respiratory syndrome (SARS) was caused by a previously unrecognized animal coronavirus that exploited opportunities provided by 'wet markets' in southern China to adapt to become a virus readily transmissible between humans. Hospitals and international travel proved to be 'amplifiers' that permitted a local outbreak to achieve global dimensions. In this review we will discuss the substantial scientific progress that has been made towards understanding the virus-SARS coronavirus (SARS-CoV)-and the disease. We will also highlight the progress that has been made towards developing vaccines and therapies The concerted and coordinated response that contained SARS is a triumph for global public health and provides a new paradigm for the detection and control of future emerging infectious disease threats.