Potential for large outbreaks of Ebola virus disease.
Ontology highlight
ABSTRACT:
SUBMITTER: Camacho A
PROVIDER: S-EPMC4255970 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Tropical forests are undergoing land use change in many regions of the world, including the African continent. Human populations living close to forest margins fragmented and disturbed by deforestation may be particularly exposed to zoonotic infections because of the higher likelihood for humans to be in contact with disease reservoirs. Quantitative analysis of the nexus between deforestation and the emergence of Ebola virus disease (EVD), however, is still missing. Here we use land cover change data in conjunction with EVD outbreak records to investigate the association between recent (2004-2014) outbreaks in West and Central Africa, and patterns of land use change in the region. We show how in these EVD outbreaks the index cases in humans (i.e. spillover from wildlife reservoirs) occurred mostly in hotspots of forest fragmentation.
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Project description:Recent evidence suggests that sexual contact may give rise to transmission of Ebola virus long after infection has been cleared from blood. We develop a simple mathematical model that incorporates contact transmission and sexual transmission parametrized from data relating to the 2013-2015 West African Ebola epidemic. The model explores scenarios where contact transmission is reduced following infection events, capturing behaviour change, and quantifies how these actions reducing transmission may be compromised by sexual transmission in terms of increasing likelihood, size and duration of outbreaks. We characterize the extent to which sexual transmission operates in terms of the probability of initial infection resolving to sexual infectiousness and the sexual transmission rate, and relate these parameters to the overall case burden. We find that sexual transmission can have large effects on epidemic dynamics (increasing attack ratios from 25% in scenarios without sexual transmission but with contact-transmission-reducing behaviour, up to 80% in equivalent scenarios with sexual transmission).
| S-EPMC4938036 | biostudies-literature
Project description:Ebola virus disease (EVD) is a contagious, severe and often lethal form of hemorrhagic fever in humans. The association of EVD outbreaks with forest clearance has been suggested previously but many aspects remained uncharacterized. We used remote sensing techniques to investigate the association between deforestation in time and space, with EVD outbreaks in Central and West Africa. Favorability modeling, centered on 27 EVD outbreak sites and 280 comparable control sites, revealed that outbreaks located along the limits of the rainforest biome were significantly associated with forest losses within the previous 2 years. This association was strongest for closed forests (>83%), both intact and disturbed, of a range of tree heights (5->19 m). Our results suggest that the increased probability of an EVD outbreak occurring in a site is linked to recent deforestation events, and that preventing the loss of forests could reduce the likelihood of future outbreaks.
| S-EPMC5662765 | biostudies-literature
Project description:The average time required to detect an Ebola virus disease (EVD) outbreak following spillover of Ebola virus (EBOV) to a primary human case has remained essentially unchanged for over 40 years, with some of the longest delays in detection occurring in recent decades. In this review, our aim was to examine the relationship between delays in detection of EVD and the duration and size of outbreaks, and we report that longer delays are associated with longer and larger EVD outbreaks. Historically, EVD outbreaks have typically been comprised of less than 100 cases (median?=?60) and have lasted less than 4 months (median?=?118 days). The ongoing outbreak in Democratic Republic of the Congo, together with the 2013-2016 west Africa outbreak, are stark outliers amidst these trends and had two of the longest delays in detection on record. While significant progress has been made in the development of EVD countermeasures, implementation during EVD outbreaks is problematic. Thus, EVD surveillance must be improved by the broad deployment of modern diagnostic tools, as prompt recognition of EVD has the potential to stem early transmission and ultimately limit the duration and size of outbreaks.
| S-EPMC7034085 | biostudies-literature
Project description:BackgroundThe origins of Ebola disease outbreaks remain enigmatic. Historically outbreaks have been attributed to spillover events from wildlife. However, recent data suggest that some outbreaks may originate from human-to-human transmission of prior outbreak strains instead of spillover. Clarifying the origins of Ebola disease outbreaks could improve detection and mitigation of future outbreaks.MethodsWe reviewed the origins of all Ebola disease outbreaks from 1976-2022 to analyze the earliest cases and characteristics of each outbreak. The epidemiology and phylogenetic relationships of outbreak strains were used to further identify the likely source of each outbreak.ResultsFrom 1976-2022 there were 35 Ebola disease outbreaks with 48 primary/index cases. While the majority of outbreaks were associated with wildlife spillover, resurgence of human-to-human transmission could account for roughly a quarter of outbreaks caused by Ebola virus. Larger outbreaks were more likely to lead to possible resurgence, and nosocomial transmission was associated with the majority of outbreaks.ConclusionWhile spillover from wildlife has been a source for many Ebola disease outbreaks, multiple outbreaks may have originated from flare-ups of prior outbreak strains. Improving access to diagnostics as well as identifying groups at risk for resurgence of ebolaviruses will be crucial to preventing future outbreaks.
| S-EPMC10651193 | biostudies-literature
Project description:The 2013-2016 Ebola Zaire virus (EBV) outbreak in West Africa resulted in over 28,000 cases and 11,000 deaths. Ebola virus disease (EVD) is a highly virulent systemic disease with a high case fatality rate of ~ 50%. EVD results in hemorrhagic fever marked by an exaggerated systemic inflammatory response, and impaired vascular and coagulation systems. The immune response of patients who either survived or died is characterized by strong differences. Notably, fatalities showed a diminished capacity to mount an appropriate immune response, resulting in high viremia and increased pro-inflammatory cytokine production. In this study, we analyzed 38 sequential samples collected from 12 patients: 8 survivors and 4 fatalities. Our analytical strategy combined three protein-based platforms covering three different fractions of the plasma proteome: the undepleted classical plasma proteome, the depleted plasma proteome, and cytokines/chemokines, using LC/MS- and antibody-based assays, resulting in over 1000 quantified host and pathogen proteins. For depletion of the most abundant plasma proteins, we advanced a perchloric acid-based precipitation method. This method is low cost, high-throughput and robust.
2022-03-29 | PXD030260 | Pride
Project description:Ebola virus disease (EVD) is a severe and frequently lethal disease caused by Ebola virus (EBOV). EVD outbreaks typically start from a single case of probable zoonotic transmission, followed by human-to-human transmission via direct contact or contact with infected bodily fluids or contaminated fomites. EVD has a high case-fatality rate; it is characterized by fever, gastrointestinal signs and multiple organ dysfunction syndrome. Diagnosis requires a combination of case definition and laboratory tests, typically real-time reverse transcription PCR to detect viral RNA or rapid diagnostic tests based on immunoassays to detect EBOV antigens. Recent advances in medical countermeasure research resulted in the recent approval of an EBOV-targeted vaccine by European and US regulatory agencies. The results of a randomized clinical trial of investigational therapeutics for EVD demonstrated survival benefits from two monoclonal antibody products targeting the EBOV membrane glycoprotein. New observations emerging from the unprecedented 2013-2016 Western African EVD outbreak (the largest in history) and the ongoing EVD outbreak in the Democratic Republic of the Congo have substantially improved the understanding of EVD and viral persistence in survivors of EVD, resulting in new strategies toward prevention of infection and optimization of clinical management, acute illness outcomes and attendance to the clinical care needs of patients.
| S-EPMC7223853 | biostudies-literature
Project description:Uganda has reported eight outbreaks caused by filoviruses between 2000 to 2016, more than any other country in the world. We used species distribution modeling to predict where filovirus outbreaks are likely to occur in Uganda to help in epidemic preparedness and surveillance. The MaxEnt software, a machine learning modeling approach that uses presence-only data was used to establish filovirus - environmental relationships. Presence-only data for filovirus outbreaks were collected from the field and online sources. Environmental covariates from Africlim that have been downscaled to a nominal resolution of 1km x 1km were used. The final model gave the relative probability of the presence of filoviruses in the study area obtained from an average of 100 bootstrap runs. Model evaluation was carried out using Receiver Operating Characteristic (ROC) plots. Maps were created using ArcGIS 10.3 mapping software. We showed that bats as potential reservoirs of filoviruses are distributed all over Uganda. Potential outbreak areas for Ebola and Marburg virus disease were predicted in West, Southwest and Central parts of Uganda, which corresponds to bat distribution and previous filovirus outbreaks areas. Additionally, the models predicted the Eastern Uganda region and other areas that have not reported outbreaks before to be potential outbreak hotspots. Rainfall variables were the most important in influencing model prediction compared to temperature variables. Despite the limitations in the prediction model due to lack of adequate sample records for outbreaks, especially for the Marburg cases, the models provided risk maps to the Uganda surveillance system on filovirus outbreaks. The risk maps will aid in identifying areas to focus the filovirus surveillance for early detection and responses hence curtailing a pandemic. The results from this study also confirm previous findings that suggest that filoviruses are mainly limited by the amount of rainfall received in an area.
| S-EPMC5614672 | biostudies-literature
Project description:As of 20 May 2016 there have been 28,646 cases and 11,323 deaths resulting from the West African Ebola virus disease (EVD) outbreak reported to the World Health Organization. There continue to be sporadic flare-ups of EVD cases in West Africa.EVD presentation is nonspecific and characterized initially by onset of fatigue, myalgias, arthralgias, headache, and fever; this is followed several days later by anorexia, nausea, vomiting, diarrhea, and abdominal pain. Anorexia and gastrointestinal losses lead to dehydration, electrolyte abnormalities, and metabolic acidosis, and, in some patients, acute kidney injury. Hypoxia and ventilation failure occurs most often with severe illness and may be exacerbated by substantial fluid requirements for intravascular volume repletion and some degree of systemic capillary leak. Although minor bleeding manifestations are common, hypovolemic and septic shock complicated by multisystem organ dysfunction appear the most frequent causes of death.Males and females have been equally affected, with children (0-14 years of age) accounting for 19 %, young adults (15-44 years) 58 %, and older adults (?45 years) 23 % of reported cases. While the current case fatality proportion in West Africa is approximately 40 %, it has varied substantially over time (highest near the outbreak onset) according to available resources (40-90 % mortality in West Africa compared to under 20 % in Western Europe and the USA), by age (near universal among neonates and high among older adults), and by Ebola viral load at admission.While there is no Ebola virus-specific therapy proven to be effective in clinical trials, mortality has been dramatically lower among EVD patients managed with supportive intensive care in highly resourced settings, allowing for the avoidance of hypovolemia, correction of electrolyte and metabolic abnormalities, and the provision of oxygen, ventilation, vasopressors, and dialysis when indicated. This experience emphasizes that, in addition to evaluating specific medical treatments, improving the global capacity to provide supportive critical care to patients with EVD may be the greatest opportunity to improve patient outcomes.
| S-EPMC4965892 | biostudies-other
Project description:Since its initial outbreak in 1976, Ebola virus disease (EVD) has affected thousands of people, causing severe illness with high mortality rates. In the absence of a vaccine or effective specific treatment, as well as the lack of early diagnostic and detective methods, the EVD outbreak has generated a significant worldwide health concern. Insufficient health-care system resources, deficient infection control measures, and the shortage of appropriate personal protective equipment acted as amplifiers of the outbreak extension, especially in poorly resourced and unprepared communities. Operating on the frontlines, health-care workers must be familiar, not only with the identification of the disease, but also with the ability to protect themselves and initiate the appropriate response. This review seeks to provide essential information required to identify and manage the disease, with an emphasis on pathogenesis, transmission, diagnosis, treatment, and prevention. We conducted a literature search in MEDLINE/PubMed and Google Scholar using the following keywords: "Ebola, Ebola virus disease, Hemorrhagic Fever, Outbreak." We included all types of publications. To augment our study, we searched the reference lists of identified reviews.
| S-EPMC5525473 | biostudies-other