Wild animal mortality monitoring and human Ebola outbreaks, Gabon and Republic of Congo, 2001-2003

Molecular determinants of cross-species transmission in emerging viral infections

SUMMARYSeveral examples of high-impact cross-species transmission of newly emerging or re-emerging bat-borne viruses, such as Sudan virus, Nipah virus, and severe acute respiratory syndrome coronavirus 2, have occurred in the past decades. Recent advancements in next-generation sequencing have strengthened ongoing efforts to catalog the global virome, in particular from the multitude of different bat species. However, functional characterization of these novel viruses and virus sequences is typically limited with regard to assessment of their cross-species potential. Our understanding of the intricate interplay between virus and host underlying successful cross-species transmission has focused on the basic mechanisms of entry and replication, as well as the importance of host innate immune responses. In this review, we discuss the various roles of the respective molecular mechanisms underlying cross-species transmission using different recent bat-borne viruses as examples. To delineate the crucial cellular and molecular steps underlying cross-species transmission, we propose a framework of overall characterization to improve our capacity to characterize viruses as benign, of interest, or of concern.

Lethal combats in the forest among wild western gorillas

Lethal intergroup encounters occur in many species because of sexual selection. While documented in mountain gorillas, they are absent in western gorillas as, instead, it is predicted by their higher feeding (frugivory) and mate competition (single-vs. multi-male groups). We investigate whether the injuries on three dead silverbacks and one adult female from four groups of western gorillas in the Central African Republic, resulted from interactions with gorillas or leopards. We identified two distinct injury patterns caused by gorillas (isolated lacerations, round wounds) and leopards (punctures clustered on head/neck) by analyzing injuries caused by mountain gorillas and leopards to gorillas and non-gorilla species, respectively. The western gorilla injury pattern is similar to that of mountain gorillas suggesting that lethal encounters occur, albeit infrequently, as predicted by sexual selection in a one-male society. While sexual dimorphism and polygynous sociality favored the evolution of violent encounters, multiple males in groups may influence their frequency.

An experimental game to assess hunter's participation in zoonotic diseases surveillance

BACKGROUND

Strengthening the surveillance of zoonotic diseases emergence in the wild meat value chains is a critical component of the prevention of future health crises. Community hunters could act as first-line observers in zoonotic pathogens surveillance systems in wildlife, by reporting early signs of the possible presence of a disease in the game animals they observe and manipulate on a regular basis.

METHODS

An experimental game was developed and implemented in a forested area of Gabon, in central Africa. Our objective was to improve our understanding of community hunters' decision-making when finding signs of zoonotic diseases in game animals: would they report or dissimulate these findings to a health agency? 88 hunters, divided into 9 groups of 5 to 13 participants, participated in the game, which was run over 21 rounds. In each round the players participated in a simulated hunting trip during which they had a chance of capturing a wild animal displaying clinical signs of a zoonotic disease. When signs were visible, players had to decide whether to sell/consume the animal or to report it. The last option implied a lowered revenue from the hunt but an increased probability of early detection of zoonotic diseases with benefits for the entire group of hunters.

RESULTS

The results showed that false alerts-i.e. a suspect case not caused by a zoonotic disease-led to a decrease in the number of reports in the next round (Odds Ratio [OR]: 0.46, 95% Confidence Interval [CI]: 0.36-0.8, p < 0.01). Hunters who had an agricultural activity in addition to hunting reported suspect cases more often than others (OR: 2.05, 95% CI: 1.09-3.88, p < 0.03). The number of suspect case reports increased with the rank of the game round (Incremental OR: 1.11, CI: 1.06-1.17, p < 0.01) suggesting an increase in participants' inclination to report throughout the game.

CONCLUSION

Using experimental games presents an added value for improving the understanding of people's decisions to participate in health surveillance systems.

Robust evidence for bats as reservoir hosts is lacking in most African virus studies: a review and call to optimize sampling and conserve bats

Africa experiences frequent emerging disease outbreaks among humans, with bats often proposed as zoonotic pathogen hosts. We comprehensively reviewed virus-bat findings from papers published between 1978 and 2020 to evaluate the evidence that African bats are reservoir and/or bridging hosts for viruses that cause human disease. We present data from 162 papers (of 1322) with original findings on (1) numbers and species of bats sampled across bat families and the continent, (2) how bats were selected for study inclusion, (3) if bats were terminally sampled, (4) what types of ecological data, if any, were recorded and (5) which viruses were detected and with what methodology. We propose a scheme for evaluating presumed virus-host relationships by evidence type and quality, using the contrasting available evidence for Orthoebolavirus versus Orthomarburgvirus as an example. We review the wording in abstracts and discussions of all 162 papers, identifying key framing terms, how these refer to findings, and how they might contribute to people's beliefs about bats. We discuss the impact of scientific research communication on public perception and emphasize the need for strategies that minimize human-bat conflict and support bat conservation. Finally, we make recommendations for best practices that will improve virological study metadata.

Extensive Survey and Analysis of Factors Associated with Presence of Antibodies to Orthoebolaviruses in Bats from West and Central Africa

The seroprevalence to orthoebolaviruses was studied in 9594 bats (5972 frugivorous and 3622 insectivorous) from Cameroon, the Democratic Republic of Congo (DRC) and Guinea, with a Luminex-based serological assay including recombinant antigens of four orthoebolavirus species. Seroprevalence is expressed as a range according to different cut-off calculations. Between 6.1% and 18.9% bat samples reacted with at least one orthoebolavirus antigen; the highest reactivity was seen with Glycoprotein (GP) antigens. Seroprevalence varied per species and was higher in frugivorous than insectivorous bats; 9.1-27.5% versus 1.3-4.6%, respectively. Seroprevalence in male (13.5%) and female (14.4%) bats was only slightly different and was higher in adults (14.9%) versus juveniles (9.4%) (p < 0.001). Moreover, seroprevalence was highest in subadults (45.4%) when compared to mature adults (19.2%), (p < 0.001). Our data suggest orthoebolavirus circulation is highest in young bats. More long-term studies are needed to identify birthing pulses for the different bat species in diverse geographic regions and to increase the chances of detecting viral RNA in order to document the genetic diversity of filoviruses in bats and their pathogenic potential for humans. Frugivorous bats seem more likely to be reservoirs of orthoebolaviruses, but the role of insectivorous bats has also to be further examined.

Praemonitus praemunitus: can we forecast and prepare for future viral disease outbreaks?

Understanding the origins of past and present viral epidemics is critical in preparing for future outbreaks. Many viruses, including SARS-CoV-2, have led to significant consequences not only due to their virulence, but also because we were unprepared for their emergence. We need to learn from large amounts of data accumulated from well-studied, past pandemics and employ modern informatics and therapeutic development technologies to forecast future pandemics and help minimize their potential impacts. While acknowledging the complexity and difficulties associated with establishing reliable outbreak predictions, herein we provide a perspective on the regions of the world that are most likely to be impacted by future outbreaks. We specifically focus on viruses with epidemic potential, namely SARS-CoV-2, MERS-CoV, DENV, ZIKV, MAYV, LASV, noroviruses, influenza, Nipah virus, hantaviruses, Oropouche virus, MARV, and Ebola virus, which all require attention from both the public and scientific community to avoid societal catastrophes like COVID-19. Based on our literature review, data analysis, and outbreak simulations, we posit that these future viral epidemics are unavoidable, but that their societal impacts can be minimized by strategic investment into basic virology research, epidemiological studies of neglected viral diseases, and antiviral drug discovery.

Ebola virus disease: A narrative review

Ebola virus disease (EVD), which is also referred to as Ebola hemorrhagic fever, is a highly contagious and frequently lethal sickness caused by the Ebola virus. In 1976, the disease emerged in two simultaneous outbreaks in Sudan and the Democratic Republic of Congo. Subsequently, it has caused intermittent outbreaks in several African nations. The virus is primarily spread via direct contact with the bodily fluids of an infected individual or animal. EVD is distinguished by symptoms such as fever, fatigue, muscle pain, headache, and hemorrhage. The outbreak of EVD in West Africa in 2014-2016 emphasized the need for effective control and prevention measures. Despite advancements and the identification of new treatments for EVD, the primary approach to treatment continues to be centered around providing supportive care. Early detection and supportive care can enhance the likelihood of survival. This includes intravenous fluids, electrolyte replacement, and treatment of secondary infections. Experimental therapies, for instance, monoclonal antibodies and antiviral drugs, have shown promising results in animal studies and some clinical trials. Some African countries have implemented the use of vaccines developed for EVD, but their effectiveness and long-term safety are still being studied. This article provides an overview of the history, transmission, symptoms, diagnosis, treatment, epidemiology, and Ebola coinfection, as well as highlights the ongoing research efforts to develop effective treatments and vaccines to combat this deadly virus.

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.

The COVID-19 pandemic in sub-Saharan Africa: The significance of presumed immune sufficiency

A novel coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in China in 2019 and later ignited a global pandemic. Contrary to expectations, the effect of the pandemic was not as devastating to Africa and its young population compared to the rest of the world. To provide insight into the possible reasons for the presumed immune sufficiency to coronavirus disease 2019 (COVID-19) in Africa, this review critically examines literature published from 2020 onwards on the dynamics of COVID-19 infection and immunity and how other prevalent infectious diseases in Africa might have influenced the outcome of COVID-19. Studies characterising the immune response in patients with COVID-19 show that the correlates of protection in infected individuals are T-cell responses against the SARS-CoV-2 spike protein and neutralising titres of immunoglobin G and immunoglobin A antibodies. In some other studies, substantial pre-existing T-cell reactivity to SARS-CoV-2 was detected in many people from diverse geographical locations without a history of exposure. Certain studies also suggest that innate immune memory, which offers protection against reinfection with the same or another pathogen, might influence the severity of COVID-19. In addition, an initial analysis of epidemiological data showed that COVID‑19 cases were not severe in some countries that implemented universal Bacillus Calmette-Guerin (BCG) vaccination policies, thus supporting the potential of BCG vaccination to boost innate immunity. The high burden of infectious diseases and the extensive vaccination campaigns previously conducted in Africa could have induced specific and non-specific protective immunity to infectious pathogens in Africans.

Traits, phylogeny and host cell receptors predict Ebolavirus host status among African mammals

We explore how animal host traits, phylogenetic identity and cell receptor sequences relate to infection status and mortality from ebolaviruses. We gathered exhaustive databases of mortality from Ebolavirus after exposure and infection status based on PCR and antibody tests. We performed ridge regressions predicting mortality and infection as a function of traits, phylogenetic eigenvectors and separately host receptor sequences. We found that mortality from Ebolavirus had a strong association to life history characteristics and phylogeny. In contrast, infection status related not just to life history and phylogeny, but also to fruit consumption which suggests that geographic overlap of frugivorous mammals can lead to spread of virus in the wild. Niemann Pick C1 (NPC1) receptor sequences predicted infection statuses of bats included in our study with very high accuracy, suggesting that characterizing NPC1 in additional species is a promising avenue for future work. We combine the predictions from our mortality and infection status models to differentiate between species that are infected and also die from Ebolavirus versus species that are infected but tolerate the virus (possible reservoirs of Ebolavirus). We therefore present the first comprehensive estimates of Ebolavirus reservoir statuses for all known terrestrial mammals in Africa.

The stochastic world of emerging viruses

The acquisition of new hosts is a fundamental mechanism by which parasitic organisms expand their host range and perpetuate themselves on an evolutionary scale. Among pathogens, viruses, due to their speed of evolution, are particularly efficient in producing new emergence events. However, even though these phenomena are particularly important to the human species and therefore specifically studied, the processes of virus emergence in a new host species are very complex and difficult to comprehend in their entirety. In order to provide a structured framework for understanding emergence in a species (including humans), a comprehensive qualitative model is an indispensable cornerstone. This model explicitly describes all the stages necessary for a virus circulating in the wild to come to the crossing of the epidemic threshold. We have therefore developed a complete descriptive model explaining all the steps necessary for a virus circulating in host populations to emerge in a new species. This description of the parameters presiding over the emergence of a new virus allows us to understand their nature and importance in the emergence process.

Drivers of African Filovirus (Ebola and Marburg) Outbreaks

Outbreaks of African filoviruses often have high mortality, including more than 11,000 deaths among 28,562 cases during the West Africa Ebola outbreak of 2014-2016. Numerous studies have investigated the factors that contributed to individual filovirus outbreaks, but there has been little quantitative synthesis of this work. In addition, the ways in which the typical causes of filovirus outbreaks differ from other zoonoses remain poorly described. In this study, we quantify factors associated with 45 outbreaks of African filoviruses (ebolaviruses and Marburg virus) using a rubric of 48 candidate causal drivers. For filovirus outbreaks, we reviewed >700 peer-reviewed and gray literature sources and developed a list of the factors reported to contribute to each outbreak (i.e., a "driver profile" for each outbreak). We compare and contrast the profiles of filovirus outbreaks to 200 background outbreaks, randomly selected from a global database of 4463 outbreaks of bacterial and viral zoonotic diseases. We also test whether the quantitative patterns that we observed were robust to the influences of six covariates, country-level factors such as gross domestic product, population density, and latitude that have been shown to bias global outbreak data. We find that, regardless of whether covariates are included or excluded from models, the driver profile of filovirus outbreaks differs from that of background outbreaks. Socioeconomic factors such as trade and travel, wild game consumption, failures of medical procedures, and deficiencies in human health infrastructure were more frequently reported in filovirus outbreaks than in the comparison group. Based on our results, we also present a review of drivers reported in at least 10% of filovirus outbreaks, with examples of each provided.

Rapid diagnostic tests versus RT-PCR for Ebola virus infections: a systematic review and meta-analysis

Objective

To evaluate the clinical accuracy of rapid diagnostic tests for the detection of Ebola virus.

Methods

We searched MEDLINE®, Embase® and Web of Science for articles published between 1976 and October 2021 reporting on clinical studies assessing the performance of Ebola virus rapid diagnostic tests compared with reverse transcription polymerase chain reaction (RT-PCR). We assessed study quality using the QUADAS-2 criteria. To estimate the pooled sensitivity and specificity of these rapid diagnostic tests, we used a bivariate random-effects meta-analysis.

Findings

Our search identified 113 unique studies, of which nine met the inclusion criteria. The studies were conducted in the Democratic Republic of the Congo, Guinea, Liberia and Sierra Leone and they evaluated 12 rapid diagnostic tests. We included eight studies in the meta-analysis. The pooled sensitivity and specificity of the rapid tests were 86% (95% confidence interval, CI: 80-91) and 95% (95% CI: 91-97), respectively. However, pooled sensitivity decreased to 83% (95% CI: 77-88) after removing outliers. Pooled sensitivity increased to 90% (95% CI: 82-94) when analysis was restricted to studies using the RT-PCR from altona Diagnostics as gold standard. Pooled sensitivity increased to 99% (95% CI: 67-100) when the analysis was restricted to studies using whole or capillary blood specimens.

Conclusion

The included rapid diagnostic tests did not detect all the Ebola virus disease cases. While the sensitivity and specificity of these tests are moderate, they are still valuable tools, especially useful for triage and detecting Ebola virus in remote areas.

Great ape health watch: Enhancing surveillance for emerging infectious diseases in great apes

Infectious diseases have the potential to extirpate populations of great apes. As the interface between humans and great apes expands, zoonoses pose an increasingly severe threat to already endangered great ape populations. Despite recognition of the threat posed by human pathogens to great apes, health monitoring is only conducted for a small fraction of the world's wild great apes (and mostly those that are habituated) meaning that outbreaks of disease often go unrecognized and therefore unmitigated. This lack of surveillance (even in sites where capacity to conduct surveillance is present) is the most significant limiting factor in our ability to quickly detect and respond to emerging infectious diseases in great apes when they first appear. Accordingly, we must create a surveillance system that links disease outbreaks in humans and great apes in time and space, and enables veterinarians, clinicians, conservation managers, national decision makers, and the global health community to respond quickly to these events. Here, we review existing great ape health surveillance programs in African range habitats to identify successes, gaps, and challenges. We use these findings to argue that standardization of surveillance across sites and geographic scales, that monitors primate health in real-time and generates early warnings of disease outbreaks, is an efficient, low-cost step to conserve great ape populations. Such a surveillance program, which we call "Great Ape Health Watch" would lead to long-term improvements in outbreak preparedness, prevention, detection, and response, while generating valuable data for epidemiological research and sustainable conservation planning. Standardized monitoring of great apes would also make it easier to integrate with human surveillance activities. This approach would empower local stakeholders to link wildlife and human health, allowing for near real-time, bidirectional surveillance at the great ape-human interface.

Zootherapy as a potential pathway for zoonotic spillover: a mixed-methods study of the use of animal products in medicinal and cultural practices in Nigeria

BACKGROUND

Understanding how and why people interact with animals is important for the prevention and control of zoonoses. To date, studies have primarily focused on the most visible forms of human-animal contact (e.g., hunting and consumption), thereby blinding One Health researchers and practitioners to the broader range of human-animal interactions that can serve as cryptic sources of zoonotic diseases. Zootherapy, the use of animal products for traditional medicine and cultural practices, is widespread and can generate opportunities for human exposure to zoonoses. Existing research examining zootherapies omits details necessary to adequately assess potential zoonotic risks.

METHODS

We used a mixed-methods approach, combining quantitative and qualitative data from questionnaires, key informant interviews, and field notes to examine the use of zootherapy in nine villages engaged in wildlife hunting, consumption, and trade in Cross River State, Nigeria. We analyzed medicinal and cultural practices involving animals from a zoonotic disease perspective, by including details of animal use that may generate pathways for zoonotic transmission. We also examined the sociodemographic, cultural, and environmental contexts of zootherapeutic practices that can further shape the nature and frequency of human-animal interactions.

RESULTS

Within our study population, people reported using 44 different animal species for zootherapeutic practices, including taxonomic groups considered to be "high risk" for zoonoses and threatened with extinction. Variation in use of animal parts, preparation norms, and administration practices generated a highly diverse set of zootherapeutic practices (n = 292) and potential zoonotic exposure risks. Use of zootherapy was patterned by demographic and environmental contexts, with zootherapy more commonly practiced by hunting households (OR = 2.47, p < 0.01), and prescriptions that were gender and age specific (e.g., maternal and pediatric care) or highly seasonal (e.g., associated with annual festivals and seasonal illnesses). Specific practices were informed by species availability and theories of healing (i.e., "like cures like" and sympathetic healing and magic) that further shaped the nature of human-animal interactions via zootherapy.

CONCLUSIONS

Epidemiological investigations of zoonoses and public health interventions that aim to reduce zoonotic exposures should explicitly consider zootherapy as a potential pathway for disease transmission and consider the sociocultural and environmental contexts of their use in health messaging and interventions.

Transmission models indicate Ebola virus persistence in non-human primate populations is unlikely

Infectious diseases that kill their hosts may persist locally only if transmission is appropriately balanced by susceptible recruitment. Great apes die of Ebola virus disease (EVD) and have transmitted ebolaviruses to people. However, understanding the role that apes and other non-human primates play in maintaining ebolaviruses in Nature is hampered by a lack of data. Recent serological findings suggest that few non-human primates have antibodies to EVD-causing viruses throughout tropical Africa, suggesting low transmission rates and/or high EVD mortality (Ayouba A et al. 2019 J. Infect. Dis. 220, 1599-1608 (doi:10.1093/infdis/jiz006); Mombo IM et al. 2020 Viruses 12, 1347 (doi:10.3390/v12121347)). Here, stochastic transmission models of EVD in non-human primates assuming high case-fatality probabilities and experimentally observed or field-observed parameters did not allow viral persistence, suggesting that non-human primate populations are highly unlikely to sustain EVD-causing infection for prolonged periods. Repeated introductions led to declining population sizes, similar to field observations of apes, but not viral persistence.

Enterotoxigenic Escherichia coli Heat-Stable Toxin and Ebola Virus Delta Peptide: Similarities and Differences

Enterotoxigenic Escherichia coli (ETEC) STb toxin exhibits striking structural similarity to Ebola virus (EBOV) delta peptide. Both ETEC and EBOV delta peptide are enterotoxins. Comparison of the structural and functional similarities and differences of these two toxins illuminates features that are important in induction of pathogenesis by a bacterial and viral pathogen.

The concept of one health applied to the problem of zoonotic diseases

Zoonotic diseases are a burden on healthcare systems globally, particularly underdeveloped nations. Numerous vertebrate animals (e.g., birds, mammals and reptiles) serve as amplifier hosts or reservoirs for viral zoonoses. The spread of zoonotic disease is associated with environmental factors, climate change, animal health as well as other human activities including globalization, urbanization and travel. Diseases at the human-animal environment interface (e.g., zoonotic diseases, vector-borne diseases, food/water borne diseases) continue to pose risk to animals and humans with a great significant mortality and morbidity. It is estimated that of 1400 infectious diseases known to affect humans, 60% of them are of animal origin. In addition, 75% of the emerging infectious diseases have a zoonotic nature, worldwide. The one health concept plays an important role in the control and prevention of zoonoses by integrating animal, human, and environmental health through collaboration and communication among osteopaths, wildlife, physicians, veterinarians professionals, public health and environmental experts, nurses, dentists, physicists, biomedical engineers, plant pathologists, biochemists, and others. No one sector, organization, or person can address issues at the animal-human-ecosystem interface alone.

One Health Approach: A Data-Driven Priority for Mitigating Outbreaks of Emerging and Re-Emerging Zoonotic Infectious Diseases

This paper discusses the contributions that One Health principles can make in improving global response to zoonotic infectious disease. We highlight some key benefits of taking a One Health approach to a range of complex infectious disease problems that have defied a more traditional sectoral approach, as well as public health policy and practice, where gaps in surveillance systems need to be addressed. The historical examples demonstrate the scope of One Health, partly from an Australian perspective, but also with an international flavour, and illustrate innovative approaches and outcomes with the types of collaborative partnerships that are required.

An Overview of COVID-19 and Its Vaccines

Coronavirus pandemic, is a continuing catastrophe (COVID-19) triggered by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The virus passes into the target cells by attaching itself to a receptor i.e., Human Angiotensin-converting enzyme 2 (hACE2). It consists of Spike structures created from glycoproteins that promote the virus entry into the target cells of host. The RBD of the S1 subunit on Spike proteins binds to the hACE2 receptor, which is mostly found in the lungs, particularly type-2 pneumocytes, causing human ACE2 receptors to be downregulated. Apart from nausea, vomiting, and chest tightness, which are unusual symptoms of COVID-19, the most common causes of death and severity are respiratory failure (69.5%), sepsis or multi-organ failure (28%), cardiac failure (14.6%), and renal failure (14.6%). Viral antigen-based or viral nucleic acid-based real-time RT-PCR is recommended for the diagnosis of COVID-19 suspects. Vaccination is essential for antiviral treatment. The study was conducted on viruses based on live-attenuated or non-activated viruses, recombinant viral vectors, DNA, VLPs and soluble proteins. Vaccine from Pfizer and BioNTech was the first that showed promising data on effectiveness. 90% efficacy of the vaccine was reported. BNT-162b2 (Pfizer, BioNTech) & mRNA-1273 (Moderna) are mRNA based; AZD-1222 Ad5‑CoV (AstraZeneca; Oxford University); Ad26.COV2.S (Johnson & Johnson) are viral vector based and other vaccines have been granted emergency use authorization by FDA. Since RNA viruses are able to mutate readily and quickly the mutation in the existing strain can be Variants of concern (VOCs) that might diminish vaccine effectiveness. The latest Delta variant (B.1.671.2) has rapidly spread in India is emerging in the United States in mid-2021. It turns out to be the chief which is 6–8 fold more resistant to neutralization by sera from COVID-19 convalescent and mRNA vaccinated individuals.

High level of intrinsic phenotypic antimicrobial resistance in enterobacteria from terrestrial wildlife in Gabonese national parks

Data on the prevalence of antibiotic resistance in Enterobacteriaceae in African wildlife are still relatively limited. The aim of this study was to estimate the prevalence of phenotypic intrinsic and acquired antimicrobial resistance of enterobacteria from several species of terrestrial wild mammals in national parks of Gabon. Colony culture and isolation were done using MacConkey agar. Isolates were identified using the VITEK 2 and MALDI-TOF methods. Antibiotic susceptibility was analysed and interpreted according to the European Committee on Antimicrobial Susceptibility Testing guidelines. The preliminary test for ESBL-producing Enterobacteriaceae was performed by replicating enterobacterial colonies on MacConkey agar supplemented with 2 mg/L cefotaxime (MCA+CTX). Extended-spectrum beta-lactamase (ESBL) production was confirmed with the double-disc synergy test (DDST). The inhibition zone diameters were read with SirScan. Among the 130 bacterial colonies isolated from 125 fecal samples, 90 enterobacterial isolates were identified. Escherichia coli (61%) was the most prevalent, followed by Enterobacter cloacae (8%), Proteus mirabilis (8%), Klebsiella variicola (7%), Klebsiella aerogenes (7%), Klebsiella oxytoca (4%), Citrobacter freundii (3%), Klebsiella pneumoniae (1%) and Serratia marcescens (1%). Acquired resistance was carried by E. coli (11% of all E. coli isolates) and E. cloacae (3% of all E. cloacae) isolates, while intrinsic resistance was detected in all the other resistant isolates (n = 31); K. variicola, K. oxytoca, K. pneumoniae, E. cloacae, K. aerogenes, S. marcescens and P. mirabilis). Our data show that most strains isolated in protected areas in Gabon are wild type isolates and carry intrinsic resistance rather than acquired resistance.

The genetic impact of an Ebola outbreak on a wild gorilla population

Background

Numerous Ebola virus outbreaks have occurred in Equatorial Africa over the past decades. Besides human fatalities, gorillas and chimpanzees have also succumbed to the fatal virus. The 2004 outbreak at the Odzala-Kokoua National Park (Republic of Congo) alone caused a severe decline in the resident western lowland gorilla (Gorilla gorilla gorilla) population, with a 95% mortality rate. Here, we explore the immediate genetic impact of the Ebola outbreak in the western lowland gorilla population.

Results

Associations with survivorship were evaluated by utilizing DNA obtained from fecal samples from 16 gorilla individuals declared missing after the outbreak (non-survivors) and 15 individuals observed before and after the epidemic (survivors). We used a target enrichment approach to capture the sequences of 123 genes previously associated with immunology and Ebola virus resistance and additionally analyzed the gut microbiome which could influence the survival after an infection. Our results indicate no changes in the population genetic diversity before and after the Ebola outbreak, and no significant differences in microbial community composition between survivors and non-survivors. However, and despite the low power for an association analysis, we do detect six nominally significant missense mutations in four genes that might be candidate variants associated with an increased chance of survival.

Conclusion

This study offers the first insight to the genetics of a wild great ape population before and after an Ebola outbreak using target capture experiments from fecal samples, and presents a list of candidate loci that may have facilitated their survival.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-08025-y.

Open-label, randomised, clinical trial to evaluate the immunogenicity and safety of a prophylactic vaccination of healthcare providers by administration of a heterologous vaccine regimen against Ebola in the Democratic Republic of the Congo: the study protocol

INTRODUCTION

This article describes the protocol of an Ebola vaccine clinical trial which investigates the safety and immunogenicity of a two-dose prophylactic Ebola vaccine regimen comprised of two Ebola vaccines (Ad26.ZEBOV and MVA-BN-Filo) administered 56 days apart, followed by a booster vaccination with Ad26.ZEBOV offered at either 1 year or 2 years (randomisation 1:1) after the first dose. This clinical trial is part of the EBOVAC3 project (an Innovative Medicines Initiative 2 Joint Undertaking), and is the first to evaluate the safety and immunogenicity of two different booster vaccination arms in a large cohort of adults.

METHODS AND ANALYSIS

This study is an open-label, monocentric, phase 2, randomised vaccine trial. A total of 700 healthcare providers and frontliners are planned to be recruited from the Tshuapa province in the Democratic Republic of the Congo (DRC). The primary and secondary objectives of the study assess the immunogenicity of the first (Ad26.ZEBOV), second (MVA-BN-Filo) and booster (Ad26.ZEBOV) dose. Immunogenicity is assessed through the evaluation of EBOV glycoprotein binding antibody responses after vaccination. Safety is assessed through the collection of serious adverse events from the first dose until 6 months post booster vaccination and the collection of solicited and unsolicited adverse events for 1 week after the booster dose.

ETHICS AND DISSEMINATION

The protocol was approved by the National Ethics Committee of the Ministry of Health of the DRC (n°121/CNES/BN/PMMF/2019). The clinical trial was registered on 4 December 2019 on ClinicalTrials.gov. Trial activities are planned to finish in October 2022. All participants are required to provide written informed consent and no study-related procedures will be performed until consent is obtained. The results of the trial will be added on ClinicalTrials.gov, published in peer-reviewed journals and presented at international conferences.

TRIAL REGISTRATION NUMBER

NCT04186000; Pre-results.

Scoping future outbreaks: a scoping review on the outbreak prediction of the WHO Blueprint list of priority diseases

BACKGROUND

The WHO's Research and Development Blueprint priority list designates emerging diseases with the potential to generate public health emergencies for which insufficient preventive solutions exist. The list aims to reduce the time to the availability of resources that can avert public health crises. The current SARS-CoV-2 pandemic illustrates that an effective method of mitigating such crises is the pre-emptive prediction of outbreaks. This scoping review thus aimed to map and identify the evidence available to predict future outbreaks of the Blueprint diseases.

METHODS

We conducted a scoping review of PubMed, Embase and Web of Science related to the evidence predicting future outbreaks of Ebola and Marburg virus, Zika virus, Lassa fever, Nipah and Henipaviral disease, Rift Valley fever, Crimean-Congo haemorrhagic fever, Severe acute respiratory syndrome, Middle East respiratory syndrome and Disease X. Prediction methods, outbreak features predicted and implementation of predictions were evaluated. We conducted a narrative and quantitative evidence synthesis to highlight prediction methods that could be further investigated for the prevention of Blueprint diseases and COVID-19 outbreaks.

RESULTS

Out of 3959 articles identified, we included 58 articles based on inclusion criteria. 5 major prediction methods emerged; the most frequent being spatio-temporal risk maps predicting outbreak risk periods and locations through vector and climate data. Stochastic models were predominant. Rift Valley fever was the most predicted disease. Diseases with complex sociocultural factors such as Ebola were often predicted through multifactorial risk-based estimations. 10% of models were implemented by health authorities. No article predicted Disease X outbreaks.

CONCLUSIONS

Spatiotemporal models for diseases with strong climatic and vectorial components, as in River Valley fever prediction, may currently best reduce the time to the availability of resources. A wide literature gap exists in the prediction of zoonoses with complex sociocultural and ecological dynamics such as Ebola, COVID-19 and especially Disease X.

Africa and the Nexus of poverty, malnutrition and diseases

This review examines the nexus of poverty, malnutrition and diseases in Africa, the challenges, implications and their mitigation. The paper takes a critical look at available literatures on the primary causes, modes, implications and solutions to the problems of poverty, malnutrition and diseases in Africa continent. Poverty and malnutrition are outcomes of uncontrolled rapid population growth, inefficient agricultural and industrial practices, high debt profile of many African countries due to poor governance and corruption, diseases such as AIDS epidemic, malaria, Ebola virus and COVID-19 pandemic, poor and inadequate health infrastructure and armed conflicts. African poverty scenario entails non-availability of basic human needs which makes many Africans to be very poor. Despite abundance of natural resources, the gross domestic product per capita of many African countries is among the lowest of list of nations of the world. According United Nation in 2009, 22 of 24 nations among the "Low Human Development" nations of the world on the UN's Human Development Index were found in sub-Saharan Africa. Out of the 50 countries on the United Nation list of least developed countries, 34 of them were in Africa. According to FAO data over 200 million people in sub-Saharan Africa were undernourished in 2014-2016. The prevalence of undernourishment in sub-Saharan Africa rose from 181 million in 2010 to 222 million in 2016. In 2016, Africa had the highest prevalence of undernourishment in the world and estimated to be 20% of the population. While this was alarming in Eastern Africa where one-third of the population is suspected to be undernourished. In a similar data, World Bank also found that sub-Saharan Africa Poverty and Equity Data was 47% with over 500 million people in abject poverty in 2012. Poverty is the major cause of hunger and malnutrition in Africa while hunger and malnutrition escalated the problem of diseases in African continent. Poverty has continued to torment Africa as a result of poor and harmful economic policies, conflict and war, environmental factors like drought and climate change and population growth, poor leadership and greed. With the advent of COVID-19, the problem of poverty, malnutrition and diseases has been escalated and in many African countries people find it difficult to make ends meet.

Development and validation of portable, field-deployable Ebola virus point-of-encounter diagnostic assay for wildlife surveillance

Early detection of Ebola virus spillover into wildlife is crucial for rapid response. We developed and validated a portable, cold-chain independent Ebola virus RT-qPCR assay.

METHODS

The field syringe-based RNA extraction method was compared with a conventional laboratory-based spin-column RNA extraction method. Next, the qPCR efficiency and limit of detection of the assay was compared to standard laboratory-based reagents and equipment. The specificity of the assay was confirmed by testing against multiple Zaire Ebolavirus (EBOV) variants and other ebolavirus species. Lastly, swabs from an EBOV-infected non-human primate carcass, stored at environmental conditions mimicking central and west Africa, were analyzed to mimic in field conditions.

RESULTS

The syringe-based RNA extraction method performed comparably to a standard laboratory spin-column-based method. The developed assay was comparable in sensitivity and specificity to standard laboratory-based diagnostic assays. The assay specifically detected EBOV and not any of the other tested ebolavirus species, including Reston ebolavirus, Sudan ebolavirus, Bundibugyo ebolavirus, and Tai Forrest ebolavirus. Notably, the assays limit of detection for EBOV isolates were all below 4 genome copies/μL. The assay was able to detect EBOV in oral, nasal, thoracic cavity, and conjunctiva swabs obtained from an infected non-human primate.

CONCLUSION

We developed a field-based Ebolavirus assay which is comparable in sensitivity and specificity to laboratory-based assays. Currently, the assay is being incorporated into wildlife carcass surveillance in the Republic of the Congo and is being adapted for other infectious disease agents.

The Concept, Practice, Application, and Results of Locally Based Monitoring of the Environment

Locally based monitoring is typically undertaken in areas in which communities have a close attachment to their natural resource base. We present a summary of work to develop a theoretical and practical understanding of locally based monitoring and we outline tests of this approach in research and practice over the past 20 years. Our tests show that locally based monitoring delivers credible data at local scale independent of external experts and can be used to inform local and national decision making within a short timeframe. We believe that monitoring conducted by and anchored in communities will gain in importance where scientist-led monitoring is sparse or too expensive to sustain and for ecosystem attributes in cases in which remote sensing cannot provide credible data. The spread of smartphone technology and online portals will further enhance the importance and usefulness of this discipline.

Wildlife-pet markets in a one-health context

Background and Aim: Wildlife markets are centers of trade involving live animals and their derivatives from wild-caught and captive-bred non-domesticated animals, including for the culinary, fashion, traditional medicine, curio, and pet sectors. These markets occur in Southeast Asia, India, North America, Latin America, Europe, Africa, and elsewhere. This study aims to address a diversity of related issues that have a one-health bearing while focusing on wildlife markets in relation to the pet trade. Across relevant regions and countries, all major animal classes are traded at wildlife-pet markets. Wildlife markets, in general, are considered distinct from so-called "wet markets" at which domesticated animals, fish, and other "seafood" are offered only for consumption. Several aspects of wildlife markets have attracted scientific and popular scrutiny, including animal welfare concerns, species conservation threats, legality, ecological alteration, introduction of invasive alien species, presence of undescribed species, and public and agricultural animal health issues. Materials and Methods: Onsite inspections were conducted for markets in the United States, Spain, Germany, The Netherlands, and the UK, as well as observational research of visual imagery of market conditions, and we compared these conditions with evidence-based standards for animal welfare and public health management. Results: Wildlife markets globally shared common similar structures and practices including the presence of sick, injured, or stressed animals; mixing of animals of uncertain origin and health state; and no specific or any hygiene protocols, with issues of animal welfare, public health and safety, agricultural animal health, and other one-health concerns being inherently involved. Conclusion: We conclude that wildlife markets are incompatible with responsible standards and practices, and we recommend that such events are banned globally to ameliorate inherent major problems.

Politics of disease control in Africa and the critical role of global health diplomacy: A systematic review

Background: Africa is facing the triple burden of communicable diseases, non-communicable diseases (NCDs), and nutritional disorders. Multilateral institutions, bilateral arrangements, and philanthropies have historically privileged economic development over health concerns. That focus has resulted in weak health systems and inadequate preparedness when there are outbreaks of diseases. This review aims to understand the politics of disease control in Africa and global health diplomacy’s (GHD’s) critical role.

Methods: A literature review was done in Medline/PubMed, Web of Science, Scopus, Embase, and Google scholar search engines. Keywords included MeSH and common terms related to the topics: "Politics," "disease control," "epidemics/ endemics," and "global health diplomacy" in the "African" context. The resources also included reports of World Health Organization, United Nations and resolutions of the World Health Assembly (WHA).

Results: African countries continue to struggle in their attempts to build health systems for disease control that are robust enough to tackle the frequent epidemics that plague the continent. The politics of disease control requires the crafting of cooperative partnerships to accommodate the divergent interests of multiple actors. Recent outbreaks of COVID-19 and Ebola had a significant impact on African economies. It is extremely important to prioritize health in the African development agendas. The African Union (AU) should leverage the momentum of the rise of GHD to (i) navigate the politics of global health governance in an interconnected world(ii) develop robust preparedness and disease response strategies to tackle emerging and reemerging disease epidemics in the region (iii) address the linkages between health and broader human security issues driven by climate change-induced food, water, and other insecurities (iv) mobilize resources and capacities to train health officials in the craft of diplomacy.

Conclusion: The AU, Regional Economic Communities (RECs), and African Centres for Disease Control should harmonize their plans and strategies and align them towards a common goal that integrates health in African development agendas. The AU must innovatively harness the practice and tools of GHD towards developing the necessary partnerships with relevant actors in the global health arena to achieve the health targets of the Sustainable Development Goals.

Epidemiology and pathobiology of SARS-CoV-2 (COVID-19) in comparison with SARS, MERS: An updated overview of current knowledge and future perspectives

Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) is the causative etiology of ‘Corona Virus Disease-2019’ (COVID-19); formerly referred as ‘novel-Coronavirus-2019’. It was originated in Wuhan city, Hubei province, China in early December 2019. The World Health Organization (WHO) declared it as ‘Public Health Emergency of International Concern’ due to their rapid transmission and causing public and health-care-related casualties worldwide. This review provides an updated overview of COVID-19 (SARS-CoV-2), in comparison with the etiologies of the same group viz. SARS and MERS and also its future perspectives for planning appropriate strategies for prevention, control and treatment modalities to avert similar catastrophe in near future.

Detection of Ebola Virus Antibodies in Fecal Samples of Great Apes in Gabon

Based on a large study conducted on wild great ape fecal samples collected in regions of Gabon where previous human outbreaks of Ebola virus disease have occurred between 1994 and 2002, we provide evidence for prevalence of Zaire ebolavirus (EBOV)-specific antibodies of 3.9% (immunoglobulin G (IgG)) and 3.5% (immunoglobulin M (IgM)) in chimpanzees and 8.8% (IgG) and 2.4% (IgM) in gorillas. Importantly, we observed a high local prevalence (31.2%) of anti-EBOV IgG antibodies in gorilla samples. This high local rate of positivity among wild great apes raises the question of a spatially and temporally localized increase in EBOV exposure risk and the role that can be played by these animals as sentinels of the virus’s spread or reemergence in a given area.

Modelling the daily risk of Ebola in the presence and absence of a potential vaccine

Ebola virus - one of the deadliest viral diseases, with a mortality rate around 90% - damages the immune system and organs, with symptoms including episodic fever, chills, malaise and myalgia. The Recombinant Vesicular Stomatitis Virus-based candidate vaccine (rVSV-ZEBOV) has demonstrated clinical efficacy against Ebola in ring-vaccination clinical trials. In order to evaluate the potential effect of this candidate vaccine, we developed risk equations for the daily risk of Ebola infection both currently and after vaccination. The risk equations account for the basic transmission probability of Ebola and the lowered risk due to various protection protocols: vaccination, hazmat suits, reduced contact with the infected living and dead bodies. Parameter space was sampled using Latin Hypercube Sampling, a statistical method for generating a near-random sample of parameter values. We found that at a high transmission rate of Ebola (i.e., if the transmission rate is greater than 90%), a large fraction of the population must be vaccinated (>80%) to achieve a 50% decrease in the daily risk of infection. If a vaccine is introduced, it must have at least 50% efficacy, and almost everyone in the affected areas must receive it to effectively control outbreaks of Ebola. These results indicate that a low-efficacy Ebola vaccine runs the risk of having vaccinated people be overconfident in a weak vaccine and hence the possibility that the vaccine could make the situation worse, unless the population can be sufficiently educated about the necessity for high vaccine uptake.

Host Diversity and Origin of Zoonoses: The Ancient and the New

Simple Summary

There is a wide variety of diseases caused by bacteria, viruses, and parasites that are transmitted to humans by different routes from other animals. These diseases, known as zoonoses, represent 75% of new or reemerging infectious diseases. There is a considerable impact of these diseases on the economy and health at local and global levels, including zoonotic diseases caused by the ingestion of food and products derived from animals. The wide range of animal species that host these disease-causing organisms include all groups of mammals. Birds are the second significant animal group to act as hosts for zoonoses. Much progress has been made in understanding disease evolution and animal origin, with important contributions from fields such as paleopathology and analysis of DNA, applied to ancient human bone remains. The study of ancient diseases such as brucellosis and tuberculosis benefits from these approaches. More research is needed as new diseases emerge causing pandemics and some previously eradicated reemerge in some regions. Global efforts are focused, based on evidence generated by research, on the prevention of new pandemics.

Abstract

Bacterial, viral, and parasitic zoonotic diseases are transmitted to humans from a wide variety of animal species that act as reservoir hosts for the causative organisms. Zoonoses contribute an estimated 75% of new or reemerging infectious diseases in humans. All groups of mammals have been shown to act as hosts for transmission of different organisms that cause zoonoses, followed in importance by birds; with both wild and domestic species identified as hosts in specific cases. There has been considerable research progress leading to a better understanding of the host range, animal origin, evolution, and transmission of important zoonoses, including those caused by the ingestion of food and products derived from animals. Paleopathology studies of ancient human bone lesions, in combination with ancient DNA analysis of the causative pathogen, have contributed to our understanding of the origin of zoonotic diseases, including brucellosis and mycobacterial zoonoses. However, there are still knowledge gaps and new confirmed and potential hosts are reported locally with some frequency. Both the economic cost and burden of disease of zoonoses are substantial at local and global levels, as reflected by recent coronavirus pandemics that spread rapidly around the world. Evidence-based prevention strategies are currently a global priority increasingly recognized, especially in zoonoses-affected regions.

Preservation of Quaternary Structure in Thermostable, Lyophilized Filovirus Glycoprotein Vaccines: A Search for Stability-Indicating Assays

The filoviruses Zaire ebolavirus (EBOV), Marburg marburgvirus (MARV), and Sudan ebolavirus (SUDV) are some of the most lethal infectious agents known. To date, the Zaire ebolavirus vaccine (ERVEBO®) is the only United States Food and Drug Administration (FDA) approved vaccine available for any species of filovirus. However, the ERVEBO® vaccine requires cold-chain storage not to exceed -60 °C. Such cold-chain requirements are difficult to maintain in low- and middle-income countries where filovirus outbreaks originate. To improve the thermostability of filovirus vaccines in order to potentially relax or eliminate these cold-chain requirements, monovalent subunit vaccines consisting of glycoproteins from EBOV, MARV, and SUDV were stabilized within amorphous disaccharide glasses through lyophilization. Lyophilized formulations and liquid controls were incubated for up to 12 weeks at 50 °C to accelerate degradation. To identify a stability-indicating assay appropriate for monitoring protein degradation and immunogenicity loss during these accelerated stability studies, filovirus glycoprotein secondary, tertiary, and quaternary structures and vaccine immunogenicity were measured. Size-exclusion chromatography was the most sensitive indicator of glycoprotein stability in the various formulations for all three filovirus immunogens. Degradation of the test vaccines during accelerated stability studies was reflected in changes in quaternary structure, which were discernible with size-exclusion chromatography. Filovirus glycoproteins in glassy lyophilized formulations retained secondary, tertiary, and quaternary protein structure over the incubation period, whereas the proteins within liquid controls both aggregated to form higher molecular weight species and dissociated from their native quaternary structure to form a variety of structurally-perturbed lower molecular weight species.

Human Interactions with Bat Populations in Bombali, Sierra Leone

Human contact with bats has been epidemiologically linked to several of the most recent Ebola outbreaks, including the 2014 West Africa epidemic and the 2007 Luebo, Democratic Republic of the Congo, outbreak. While fruit bats remain the likely primary reservoir for Ebola virus (Zaire ebolavirus), recent wildlife surveillance efforts have identified a new species of ebolavirus (Bombali ebolavirus) in microchiropteran insect-eating bats in West and East Africa. Given the role of bats as potential Ebola reservoirs and sources of spillover into human populations, it is critically important to understand the circumstances and behaviors that bring human populations into close contact with bats. This study explores two sites in Bombali, Sierra Leone, where human populations have had close contact with microchiropteran bats via household infestations and fruit bats by hunting practices. Through interviews and focus groups, we identify the knowledge, beliefs, perceptions, and behaviors that may potentially protect or expose individuals to zoonotic spillover through direct and indirect contact with bats. We also describe how this research was used to develop a risk reduction and outreach tool for living safely with bats.

Extensive Serological Survey of Multiple African Nonhuman Primate Species Reveals Low Prevalence of Immunoglobulin G Antibodies to 4 Ebola Virus Species

Bats are considered a reservoir species for Ebola viruses, but nonhuman primates (NHPs) have represented a source of infection in several outbreaks in humans. Here we report serological screening of blood or fecal samples from monkeys (n = 2322) and apes (n = 2327). Thirty-six NHP species from Cameroon, Democratic Republic of the Congo, and Ivory Coast were tested with a sensitive and specific Luminex-based assay for immunoglobulin G antibodies to 4 Ebola virus species. Using the simultaneous presence of antibodies to nucleoproteins and glycoproteins to define positivity, we showed that specific Ebola virus antibodies are not widespread among NHPs. Only 1 mustached monkey (Cercopithecus cephus) from Cameroon was positive for Sudan ebolavirus. These observations support that NHPs are most likely intermediate hosts for Ebola viruses. With the increasing frequency of Ebola outbreaks, it is crucial to identify the animal reservoir and understand the ecology of Ebola viruses to inform disease control.

Systematic Comparison of Two Animal-to-Human Transmitted Human Coronaviruses: SARS-CoV-2 and SARS-CoV

After the outbreak of the severe acute respiratory syndrome (SARS) in the world in 2003, human coronaviruses (HCoVs) have been reported as pathogens that cause severe symptoms in respiratory tract infections. Recently, a new emerged HCoV isolated from the respiratory epithelium of unexplained pneumonia patients in the Wuhan seafood market caused a major disease outbreak and has been named the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This virus causes acute lung symptoms, leading to a condition that has been named as "coronavirus disease 2019" (COVID-19). The emergence of SARS-CoV-2 and of SARS-CoV caused widespread fear and concern and has threatened global health security. There are some similarities and differences in the epidemiology and clinical features between these two viruses and diseases that are caused by these viruses. The goal of this work is to systematically review and compare between SARS-CoV and SARS-CoV-2 in the context of their virus incubation, originations, diagnosis and treatment methods, genomic and proteomic sequences, and pathogenic mechanisms.

Implementing One Health approaches to confront emerging and re-emerging zoonotic disease threats: lessons from PREDICT

Recurring outbreaks of emerging and re-emerging zoonoses, such as Ebola virus disease, avian influenza, and Nipah virus, serve as a reminder that the health of humans, animals, and the environment are interconnected and that early response to emerging zoonotic pathogens requires a coordinated, interdisciplinary, cross-sectoral approach. As our world becomes increasingly connected, emerging diseases pose a greater threat, requiring coordination at local, regional, and global levels. One Health is a multisectoral, transdisciplinary, and collaborative approach promoted to more effectively address these complex health threats. Despite strong advocacy for One Health, challenges for practical implementation remain. Here we discuss the value of the One Health approach for addressing global health challenges. We also share strategies applied to achieve successful outcomes through the USAID Emerging Pandemic Threats Program PREDICT project, which serve as useful case studies for implementing One Health approaches. Lastly, we explore methods for promoting more formal One Health implementation to capitalize on the added value of shared knowledge and leveraged resources.

Spillover of ebolaviruses into people in eastern Democratic Republic of Congo prior to the 2018 Ebola virus disease outbreak

BACKGROUND

The second largest Ebola virus disease (EVD) outbreak began in the Democratic Republic of Congo in July 2018 in North Kivu Province. Data suggest the outbreak is not epidemiologically linked to the 2018 outbreak in Equateur Province, and that independent introduction of Ebola virus (EBOV) into humans occurred. We tested for antibodies to ebolaviruses in febrile patients seeking care in North Kivu Province prior to the EVD outbreak.

METHODS

Patients were enrolled between May 2017 and April 2018, before the declared start of the outbreak in eastern DRC. Questionnaires were administered to collect demographic and behavioural information to identify risk factors for exposure. Biological samples were evaluated for ebolavirus nucleic acid, and for antibodies to ebolaviruses. Prevalence of exposure was calculated, and demographic factors evaluated for associations with ebolavirus serostatus.

RESULTS

Samples were collected and tested from 272 people seeking care in the Rutshuru Health Zone in North Kivu Province. All patients were negative for filoviruses by PCR. Intial screening by indirect ELISA found that 30 people were reactive to EBOV-rGP. Results were supported by detection of ebolavirus reactive linear peptides using the Serochip platform. Differential screening of all reactive serum samples against the rGP of all six ebolaviruses and Marburg virus (MARV) showed that 29 people exhibited the strongest reactivity to EBOV and one to Bombali virus (BOMV), and western blotting confirmed results. Titers ranged from 1:100 to 1:12,800. Although both sexes and all ages tested positive for antibodies, women were significantly more likely to be positive and the majority of positives were in February 2018.

CONCLUSIONS

We provide the first documented evidence of exposure to Ebola virus in people in eastern DRC. We detected antibodies to EBOV in 10% of febrile patients seeking healthcare prior to the declaration of the 2018-2020 outbreak, suggesting early cases may have been missed or exposure ocurred without associated illness. We also report the first known detection of antibodies to BOMV, previously detected in bats in West and East Africa, and show that human exposure to BOMV has occurred. Our data suggest human exposure to ebolaviruses may be more frequent and geographically widespread.

The ability of single genes vs full genomes to resolve time and space in outbreak analysis

Background

Inexpensive pathogen genome sequencing has had a transformative effect on the field of phylodynamics, where ever increasing volumes of data have promised real-time insight into outbreaks of infectious disease. As well as the sheer volume of pathogen isolates being sequenced, the sequencing of whole pathogen genomes, rather than select loci, has allowed phylogenetic analyses to be carried out at finer time scales, often approaching serial intervals for infections caused by rapidly evolving RNA viruses. Despite its utility, whole genome sequencing of pathogens has not been adopted universally and targeted sequencing of loci is common in some pathogen-specific fields.

Results

In this study we highlighted the utility of sequencing whole genomes of pathogens by re-analysing a well-characterised collection of Ebola virus sequences in the form of complete viral genomes (≈19 kb long) or the rapidly evolving glycoprotein (GP, ≈2 kb long) gene. We have quantified changes in phylogenetic, temporal, and spatial inference resolution as a result of this reduction in data and compared these to theoretical expectations.

Conclusions

We propose a simple intuitive metric for quantifying temporal resolution, i.e. the time scale over which sequence data might be informative of various processes as a quick back-of-the-envelope calculation of statistical power available to molecular clock analyses.

Ebola virus disease: An emerging and re-emerging viral threat

The genus Ebolavirus from the family Filoviridae is composed of five species including Sudan ebolavirus, Reston ebolavirus, Bundibugyo ebolavirus, Taï Forest ebolavirus, and Ebola virus (previously known as Zaire ebolavirus). These viruses have a large non-segmented, negative-strand RNA of approximately 19 kb that encodes for glycoproteins (i.e., GP, sGP, ssGP), nucleoproteins, virion proteins (i.e., VP 24, 30,40) and an RNA dependent RNA polymerase. These viruses have become a global health concern because of mortality, their rapid dissemination, new outbreaks in West-Africa, and the emergence of a new condition known as "Post-Ebola virus disease syndrome" that resembles inflammatory and autoimmune conditions such as rheumatoid arthritis, systemic lupus erythematosus and spondyloarthritis with uveitis. However, there are many gaps in the understanding of the mechanisms that may induce the development of such autoimmune-like syndromes. Some of these mechanisms may include a high formation of neutrophil extracellular traps, an uncontrolled "cytokine storm", and the possible formation of auto-antibodies. The likely appearance of autoimmune phenomena in Ebola survivors suppose a new challenge in the management and control of this disease and opens a new field of research in a special subgroup of patients. Herein, the molecular biology, pathogenesis, clinical manifestations, and treatment of Ebola virus disease are reviewed and some strategies for control of disease are discussed.

Long-term wildlife mortality surveillance in northern Congo: a model for the detection of Ebola virus disease epizootics

Ebolavirus (EBOV) has caused disease outbreaks taking thousands of lives, costing billions of dollars in control efforts and threatening great ape populations. EBOV ecology is not fully understood but infected wildlife and consumption of animal carcasses have been linked to human outbreaks, especially in the Congo Basin. Partnering with the Congolese Ministry of Health, we conducted wildlife mortality surveillance and educational outreach in the northern Republic of Congo (RoC). Designed for EBOV detection and to alert public health authorities, we established a low-cost wildlife mortality reporting network covering 50 000 km². Simultaneously, we delivered educational outreach promoting behavioural change to over 6600 people in rural northern RoC. We achieved specimen collection by training project staff on a safe sampling protocol and equipping geographically distributed bases with sampling kits. We established in-country diagnostics for EBOV testing, reducing diagnostic turnaround time to 3 days and demonstrated the absence of EBOV in 58 carcasses. Central Africa remains a high-risk EBOV region, but RoC, home to the largest remaining populations of great apes, has not had an epidemic since 2005. This effort continues to function as an untested early warning system in RoC, where people and great apes have died from past Ebola virus disease outbreaks. This article is part of the theme issue 'Dynamic and integrative approaches to understanding pathogen spillover'.

Filovirus Disease Outbreaks: A Chronological Overview

Filoviruses cause outbreaks which lead to high fatality in humans and non-human primates, thus tagging them as major threats to public health and species conservation. In this review, we give account of index cases responsible for filovirus disease outbreaks that have occurred over the past 52 years in a chronological fashion, by describing the circumstances that led to the outbreaks, and how each of the outbreaks broke out. Since the discovery of Marburg virus and Ebola virus in 1967 and 1976, respectively, more than 40 filovirus disease outbreaks have been reported; majority of which have occurred in Africa. The chronological presentation of this review is to provide a concise overview of filovirus disease outbreaks since the discovery of the viruses, and highlight the patterns in the occurrence of the outbreaks. This review will help researchers to better appreciate the need for surveillance, especially in areas where there have been no filovirus disease outbreaks. We conclude by summarizing some recommendations that have been proposed by health and policy decision makers over the years.

Serologic Evidence of Ebolavirus Infection in a Population With No History of Outbreaks in the Democratic Republic of the Congo

Background

Previous studies suggest that cases of Ebola virus disease (EVD) may go unreported because they are asymptomatic or unrecognized, but evidence is limited by study designs and sample size.

Methods

A large population-based survey was conducted (n = 3415) to assess animal exposures and behaviors associated with Ebolavirus antibody prevalence in rural Kasai Oriental province of the Democratic Republic of Congo (DRC). Fourteen villages were randomly selected and all healthy individuals ≥1 year of age were eligible.

Results

Overall, 11% of subjects tested positive for Zaire Ebolavirus (EBOV) immunoglobulin G antibodies. Odds of seropositivity were higher for study participants older than 15 years of age and for males. Those residing in Kole (closer to the outbreak site) tested positive at a rate 1.6× higher than Lomela, with seropositivity peaking at a site located between Kole and Lomela. Multivariate analyses of behaviors and animal exposures showed that visits to the forest or hunting and exposure to rodents or duikers predicted a higher likelihood of EBOV seropositivity.

Conclusions

These results provide serologic evidence of Ebolavirus exposure in a population residing in non-EBOV outbreak locations in the DRC and define statistically significant activities and animal exposures that associate with EBOV seropositivity.

Behavioral responses around conspecific corpses in adult eastern gorillas (Gorilla beringei spp.)

Humans were once considered unique in having a concept of death but a growing number of observations of animal responses to dying and dead conspecifics suggests otherwise. Complex arrays of behaviors have been described ranging from corpse removal and burial among social insects to quiet attendance and caregiving among elephants and primates. Less frequently described, however, are behavioral responses of individuals from different age/sex classes or social position toward the death of conspecifics. We describe behavioral responses of mountain gorillas (Gorilla beringei beringei) to the deaths of a dominant silverback and a dominant adult female from the same social group in Volcanoes National Park in Rwanda and the responses of Grauer’s gorillas (Gorilla b. graueri) to the corpse of an extra-group silverback in Kahuzi-Biega National Park, Democratic Republic of Congo. In gorillas, interactions between groups or with a lone silverback often result in avoidance or aggression. We predicted that: (i) more individuals should interact with the corpses of same-group members than with the corpse of the extra-group silverback; (ii) adult females with infants should avoid the corpse of the extra-group silverback; and (iii) in the mountain gorilla cases, individuals that shared close social relationships with the dead individual should spend more time with the corpse than other individuals in the group. We used a combination of detailed qualitative reports, photos, and videos to describe all occurrences of affiliative/investigative and agonistic behaviors observed at the corpses. We observed similar responses toward the corpses of group and extra-group individuals. Animals in all three cases showed a variety of affiliative/investigative and agonistic behaviors directed to the corpses. Animals of all age/sex classes interacted with the corpses in affiliative/investigative ways but there was a notable absence of all adult females at the corpse of the extra-group silverback. In all three cases, we observed only silverbacks and blackbacks being agonistic around and/or toward the corpses. In the mountain gorilla cases, the individuals who spent the most time with the corpses were animals who shared close social relationships with the deceased. We emphasize the similarity in the behavioral responses around the corpses of group and extra-group individuals, and suggest that the behavioral responses were influenced in part by close social relationships between the deceased and certain group members and by a general curiosity about death. We further discuss the implications close interactions with corpses have for disease transmission within and between gorilla social groups.

Early transmission and case fatality of Ebola virus at the index site of the 2013-16 west African Ebola outbreak: a cross-sectional seroprevalence survey

BACKGROUND

To date, epidemiological studies at the index site of the 2013-16 west African Ebola outbreak in Meliandou, Guinea, have been restricted in their scope. We aimed to determine the occurrence of previously undocumented Ebola virus disease (EVD) cases and infections, and to reconstruct transmission events.

METHODS

This cross-sectional seroprevalence survey of the adult population of Meliandou used a highly specific oral fluid test and detailed interviews of all households in the village and key informants. Each household was interviewed, with all members prompted to describe the events of the outbreak, any illness within the household, and possible contact with suspected cases. Information for deceased individuals was provided by relatives living in the same household. Symptoms were based on Ebola virus Makona variant EVD case definitions (focusing on fever, vomiting, and diarrhoea). For antibody testing, we used an Ebola virus glycoprotein IgG capture enzyme immunoassay developed from a previously validated assay. A maximum exposure level was assigned to every participant using a predetermined scale. We used a generalised linear model (logit function) to estimate odds ratios for the association of sociodemographic variables and exposure level with Ebola virus infection. We adjusted estimates for age and maximum exposure, as appropriate.

FINDINGS

Between June 22, and July 9, 2017, we enrolled 237 participants from 27 households in Meliandou. Two households refused to participate and one was absent. All adults in participating households who were present for the interview provided an oral fluid swab for testing, of which 224 were suitable for analysis. In addition to the 11 EVD deaths described previously, on the basis of clinical description and oral fluid testing, we found two probable EVD deaths and eight previously unrecognised anti-Ebola virus IgG-positive survivors, including one who had mild symptoms and one who was asymptomatic, resulting in a case fatality of 55·6% (95% CI 30·8-78·5) for adults. Health-care work (adjusted odds ratio 6·64, 1·54-28·56; p=0·001) and level of exposure (odds ratio adjusted for linear trend across five levels 2·79, 1·59-4·883; p<0·0001) were independent risk factors for infection.

INTERPRETATION

Ebola virus infection was more widespread in this spillover population than previously recognised (21 vs 11 cases). We show the first serological evidence of survivors in this population (eight anti-Ebola virus IgG seropositive) and report a case fatality lower than previously reported (55·6% vs 100% in adults). These data show the high community coverage achievable by using a non-invasive test and, by accurately documenting the beginnings of the west African Ebola virus outbreak, reveal important insight into transmission dynamics and risk factors that underpin Ebola virus spillover events.

FUNDING

US Food and Drug Administration, Wellcome Trust, and German Research Council.

A Novel Orthohepadnavirus Identified in a Dead Maxwell's Duiker (Philantomba maxwellii) in Taï National Park, Côte d'Ivoire

New technologies enable viral discovery in a diversity of hosts, providing insights into viral evolution. We used one such approach, the virome capture sequencing for vertebrate viruses (VirCapSeq-VERT) platform, on 21 samples originating from six dead Maxwell’s duikers (Philantomba maxwellii) from Taï National Park, Côte d’Ivoire. We detected the presence of an orthohepadnavirus in one animal and characterized its 3128 bp genome. The highest viral copy numbers were detected in the spleen, followed by the lung, blood, and liver, with the lowest copy numbers in the kidney and heart; the virus was not detected in the jejunum. Viral copy numbers in the blood were in the range known from humans with active chronic infections leading to liver histolytic damage, suggesting this virus could be pathogenic in duikers, though many orthohepadnaviruses appear to be apathogenic in other hosts, precluding a formal test of this hypothesis. The virus was not detected in 29 other dead duiker samples from the Côte d’Ivoire and Central African Republic, suggesting either a spillover event or a low prevalence in these populations. Phylogenetic analysis placed the virus as a divergent member of the mammalian clade of orthohepadnaviruses, though its relationship to other orthohepadnaviruses remains uncertain. This represents the first orthohepadnavirus described in an artiodactyl. We have tentatively named this new member of the genus Orthohepadnavirus (family Hepadnaviridae), Taï Forest hepadnavirus. Further studies are needed to determine whether it, or some close relatives, are present in a broader range of artiodactyls, including livestock.