Ebola virus disease: emergence, outbreak and future directions

Identifying the panorama of potential pandemic pathogens and their key characteristics: a systematic scoping review

The globe has recently seen several terrifying pandemics and outbreaks, underlining the ongoing danger presented by infectious microorganisms. This literature review aims to explore the wide range of infections that have the potential to lead to pandemics in the present and the future and pave the way to the conception of epidemic early warning systems. A systematic review was carried out to identify and compile data on infectious agents known to cause pandemics and those that pose future concerns. One hundred and fifteen articles were included in the review. They provided insights on 25 pathogens that could start or contribute to creating pandemic situations. Diagnostic procedures, clinical symptoms, and infection transmission routes were analyzed for each of these pathogens. Each infectious agent's potential is discussed, shedding light on the crucial aspects that render them potential threats to the future. This literature review provides insights for policymakers, healthcare professionals, and researchers in their quest to identify potential pandemic pathogens, and in their efforts to enhance pandemic preparedness through building early warning systems for continuous epidemiological monitoring.

Epidemiology of Ebolaviruses from an Etiological Perspective

Since the inception of the ebolavirus in 1976, 32 outbreaks have resulted in nearly 15,350 deaths in more than ten countries of the African continent. In the last decade, the largest (2013-2016) and second largest (2018-2020) ebolavirus outbreaks have occurred in West Africa (mainly Guinea, Liberia, and Sierra Leone) and the Democratic Republic of the Congo, respectively. The 2013-2016 outbreak indicated an alarming geographical spread of the virus and was the first to qualify as an epidemic. Hence, it is imperative to halt ebolavirus progression and develop effective countermeasures. Despite several research efforts, ebolaviruses' natural hosts and secondary reservoirs still elude the scientific world. The primary source responsible for infecting the index case is also unknown for most outbreaks. In this review, we summarize the history of ebolavirus outbreaks with a focus on etiology, natural hosts, zoonotic reservoirs, and transmission mechanisms. We also discuss the reasons why the African continent is the most affected region and identify steps to contain this virus.

Synthetic Platforms for Characterizing and Targeting of SARS-CoV-2 Genome Capping Enzymes

Essential viral enzymes have been successfully targeted to combat the diseases caused by emerging pathogenic RNA viruses (e.g., viral RNA-dependent RNA polymerase). Because of the conserved nature of such viral enzymes, therapeutics targeting these enzymes have the potential to be repurposed to combat emerging diseases, e.g., remdesivir, which was initially developed as a potential Ebola treatment, then was repurposed for COVID-19. Our efforts described in this study target another essential and highly conserved, but relatively less explored, step in RNA virus translation and replication, i.e., capping of the viral RNA genome. The viral genome cap structure disguises the genome of most RNA viruses to resemble the mRNA cap structure of their host and is essential for viral translation, propagation, and immune evasion. Here, we developed a synthetic, phenotypic yeast-based complementation platform (YeRC0M) for molecular characterization and targeting of SARS-CoV-2 genome-encoded RNA cap-0 (guanine-N7)-methyltransferase (N7-MTase) enzyme (nsp14). In YeRC0M, the lack of yeast mRNA capping N7-MTase in yeast, which is an essential gene in yeast, is complemented by the expression of functional viral N7-MTase or its variants. Using YeRC0M, we first identified important protein domains and amino acid residues that are essential for SARS-CoV-2 nsp14 N7-MTase activity. We also expanded YeRC0M to include key nsp14 variants observed in emerging variants of SARS-CoV-2 (e.g., delta variant of SARS-CoV-2 encodes nsp14 A394V and nsp14 P46L). We also combined YeRC0M with directed evolution to identify attenuation mutations in SARS-CoV-2 nsp14. Because of the high sequence similarity of nsp14 in emerging coronaviruses, these observations could have implications on live attenuated vaccine development strategies. These data taken together reveal key domains in SARS-CoV-2 nsp14 that can be targeted for therapeutic strategies. We also anticipate that these readily tractable phenotypic platforms can also be used for the identification of inhibitors of viral RNA capping enzymes as antivirals.

Ecology of Ebolaviruses

Africa is becoming known for the emergence and re-emergence of Ebola virus. The virus, which was initially restricted to East and Central Africa, is now emerging in West Africa. Ecological aspects of Ebola virus diseases are poorly understood. It is suspected that the virus is circulating in the forests of Africa, mostly hosted by migratory bats, which spread the virus to other wildlife particularly great apes and duikers. Spillovers occur when humans have contacts with wildlife. Transmission of the virus within human systems occurs through contacts with body fluids of an infected person. Several factors seem to be responsible for the emergence and re-emergence of the virus in Africa including circulation of the virus in forest ecosystems, persistence of the virus in body fluids (during sickness, upon death, and in survivors), transmission through diverse routes (direct contacts, fomites, oral), presence of infected migratory bats and other wildlife species, forest encroachment, and climatic and seasonal changes. Recent studies show that fresh outbreaks can emerge not only from wildlife but also from survivors of previous outbreaks. It is therefore important to understand the ecology of the virus in order to mitigate future emergence.

Interprofessional perceptions of emotional, social, and ethical effects of multidrug-resistant organisms: A qualitative study

INTRODUCTION

Multi-drug-resistant organisms (MDRO) are usually managed by separating the infected patients to protect others from colonization and infection. Isolation precautions are associated with negative experiences by patients and their relatives, while hospital staff experience a heavier workload and their own emotional reactions.

METHODS

In 2018, 35 participants (nurses, physicians, pharmacists) in an antimicrobial-stewardship program participated in facilitated discussion groups working on the emotional impact of MDRO. Deductive codings were done by four coders focusing on the five basic emotions described by Paul Ekmans.

RESULTS

All five emotions revealed four to 11 codes forming several subthemes: Anger is expressed because of incompetence, workflow-impairment and lack of knowledge. Anxiety is provoked by inadequate knowledge, guilt, isolation, bad prognoses, and media-related effects. Enjoyment is seldom. Sadness is experienced in terms of helplessness and second-victim effects. Disgust is attributed to shame and bad associations, but on the other hand MDROs seem to be part of everyday life. Deductive coding yielded additional codes for bioethics and the Calgary Family Assessment Method.

CONCLUSION

MDRO are perceived to have severe impact on emotions and may affect bioethical and family psychological issues. Thus, further work should concentrate on these findings to generate a holistic view of MDRO on human life and social systems.

Serologic Markers for Ebolavirus Among Healthcare Workers in the Democratic Republic of the Congo

Healthcare settings have played a major role in propagation of Ebola virus (EBOV) outbreaks. Healthcare workers (HCWs) have elevated risk of contact with EBOV-infected patients, particularly if safety precautions are not rigorously practiced. We conducted a serosurvey to determine seroprevalence against multiple EBOV antigens among HCWs of Boende Health Zone, Democratic Republic of the Congo, the site of a 2014 EBOV outbreak. Interviews and specimens were collected from 565 consenting HCWs. Overall, 234 (41.4%) of enrolled HCWs were reactive to at least 1 EBOV protein: 159 (28.1%) were seroreactive for anti-glycoprotein immunoglobulin G (IgG), 89 (15.8%) were seroreactive for anti-nucleoprotein IgG, and 54 (9.5%) were VP40 positive. Additionally, sera from 16 (2.8%) HCWs demonstrated neutralization capacity. These data demonstrate that a significant proportion of HCWs have the ability to neutralize virus, despite never having developed Ebola virus disease symptoms, highlighting an important and poorly documented aspect of EBOV infection and progression.

Viral infections of the central nervous system in Africa

Viral infections are a major cause of human central nervous system infection, and may be associated with significant mortality, and long-term sequelae. In Africa, the lack of effective therapies, limited diagnostic and human resource facilities are especially in dire need. Most viruses that affect the central nervous system are opportunistic or accidental pathogens. Some of these viruses were initially considered harmless, however they have now evolved to penetrate the nervous system efficiently and exploit neuronal cell biology thus resulting in severe illness. A number of potentially lethal neurotropic viruses have been discovered in Africa and over the course of time shown their ability to spread wider afield involving other continents leaving a devastating impact in their trail. In this review we discuss key viruses involved in central nervous system disease and of major public health concern with respect to Africa. These arise from the families of Flaviviridae, Filoviridae, Retroviridae, Bunyaviridae, Rhabdoviridae and Herpesviridae. In terms of the number of cases affected by these viruses, HIV (Retroviridae) tops the list for morbidity, mortality and long term disability, while the Rift Valley Fever virus (Bunyaviridae) is at the bottom of the list. The most deadly are the Ebola and Marburg viruses (Filoviridae). This review describes their epidemiology and key neurological manifestations as regards the central nervous system such as meningoencephalitis and Guillain-Barré syndrome. The potential pathogenic mechanisms adopted by these viruses are debated and research perspectives suggested.

Global nursing in an Ebola viral haemorrhagic fever outbreak: before, during and after deployment

BACKGROUND

Nurses are on the forefront and play a key role in global disaster responses. Nevertheless, they are often not prepared for the challenges they are facing and research is scarce regarding the nursing skills required for first responders during a disaster situation.

OBJECTIVES

To investigate how returnee nursing staff experienced deployment before, during and after having worked for the Red Cross at an Ebola Treatment Center in Kenema, West Africa, and to supply knowledge on how to better prepare and support staff for viral haemorrhagic fever outbreaks.

METHODS

A descriptive, cross-sectional approach. Questionnaires were administered to nurses having worked with patients suffering from Ebola in 2014 and 2015. Data collection covered aspects of pre-, during and post-deployment on clinical training, personal health, stress management, leadership styles, socio-cultural exposure and knowledge transfer, as well as attitudes from others. Data was analysed using both quantitative and qualitative methods.

RESULTS

Response-rate was 88%: forty-four nurses from 15 different countries outside West Africa answered the questionnaire. The respondents identified the following needs for improvement: increased mental health and psychosocial support and hands-on coping strategies with focus on pre- and post-deployment; more pre-deployment task-oriented clinical training; and workload reduction, as exhaustion is a risk for safety.

CONCLUSIONS

This study supplies knowledge on how to better prepare health care staff for future viral haemorrhagic fever outbreaks and other disasters. Participants were satisfied with their pre-deployment physical health preparation, whereas they stressed the importance of mental health support combined with psychosocial support after deployment. Furthermore, additional pre-clinical training was requested.

The Application of Humanized Mouse Models for the Study of Human Exclusive Viruses

The symbiosis between humans and viruses has allowed human tropic pathogens to evolve intricate means of modulating the human immune response to ensure its survival among the human population. In doing so, these viruses have developed profound mechanisms that mesh closely with our human biology. The establishment of this intimate relationship has created a species-specific barrier to infection, restricting the virus-associated pathologies to humans. This specificity diminishes the utility of traditional animal models. Humanized mice offer a model unique to all other means of study, providing an in vivo platform for the careful examination of human tropic viruses and their interaction with human cells and tissues. These types of animal models have provided a reliable medium for the study of human-virus interactions, a relationship that could otherwise not be investigated without questionable relevance to humans.

Analysis of Diagnostic Findings From the European Mobile Laboratory in Guéckédou, Guinea, March 2014 Through March 2015

Background. A unit of the European Mobile Laboratory (EMLab) consortium was deployed to the Ebola virus disease (EVD) treatment unit in Guéckédou, Guinea, from March 2014 through March 2015.

Methods. The unit diagnosed EVD and malaria, using the RealStar Filovirus Screen reverse transcription–polymerase chain reaction (RT-PCR) kit and a malaria rapid diagnostic test, respectively.

Results. The cleaned EMLab database comprised 4719 samples from 2741 cases of suspected EVD from Guinea. EVD was diagnosed in 1231 of 2178 hospitalized patients (57%) and in 281 of 563 who died in the community (50%). Children aged <15 years had the highest proportion of Ebola virus–malaria parasite coinfections. The case-fatality ratio was high in patients aged <5 years (80%) and those aged >74 years (90%) and low in patients aged 10–19 years (40%). On admission, RT-PCR analysis of blood specimens from patients who died in the hospital yielded a lower median cycle threshold (Ct) than analysis of blood specimens from survivors (18.1 vs 23.2). Individuals who died in the community had a median Ct of 21.5 for throat swabs. Multivariate logistic regression on 1047 data sets revealed that low Ct values, ages of <5 and ≥45 years, and, among children aged 5–14 years, malaria parasite coinfection were independent determinants of a poor EVD outcome.

Conclusions. Virus load, age, and malaria parasite coinfection play a role in the outcome of EVD.