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1.
The explosive outbreak of Ebola virus disease (EVD) in West Africa in 2014 appeared to have lessened in 2015, but potentially continues be a global public health threat. A simple mathematical model, the Richards model, is utilized to gauge the temporal variability in the spread of the Ebola virus disease (EVD) in West Africa in terms of its reproduction number R and its temporal changes via detection of epidemic waves and turning points during the 2014 outbreaks in the three most severely affected countries; namely, Guinea, Liberia, and Sierra Leone. The results reveal multiple waves of infection in each of these three countries, of varying lengths from a little more than one week to more than one month. All three countries exhibit marginally fluctuating reproduction numbers during June-October before gradually declining. Although high mobility continues between neighboring populations of these countries across the borders, outbreak in these three countries exhibits decidedly different temporal patterns. Guinea had the most waves but maintained consistently low transmissibility and hence has the smallest number of reported cases. Liberia had highest level of transmission before October, but has remained low since, with no detectable wave after the New Year. Sierra Leone has gradually declining waves since October, but still generated detectable waves up to mid-March 2015, and hence has cumulated the largest number of cases—exceeding that of Guinea and Liberia combined. Analysis indicates that, despite massive amount of international relief and intervention efforts, the outbreak is persisting in these regions in waves, albeit more sparsely and at a much lower level since the beginning of 2015.  相似文献   

2.
In 2000, we investigated the Rift Valley fever (RVF) outbreak on the Arabian Peninsula—the first outside Africa—and the risk of nosocomial transmission. In a cross-sectional design, during the peak of the epidemic at its epicenter, we found four (0.6%) of 703 healthcare workers (HCWs) IgM seropositive but all with only community-associated exposures. Standard precautions are sufficient for HCWs exposed to known RVF patients, in contrast to other viral hemorrhagic fevers (VHF) such as Ebola virus disease (EVD) in which the route of transmission differs. Suspected VHF in which the etiology is uncertain should be initially managed with the most cautious infection control measures.  相似文献   

3.
BackgroundEbola virus disease is a highly virulent and transmissible disease. The largest recorded fatality from Ebola virus disease epidemic is ongoing in a few countries in West Africa, and this poses a health risk to the entire population of the world because arresting the transmission has been challenging. Vaccination is considered a key intervention that is capable of arresting further spread of the disease and preventing future outbreak. However, no vaccine has yet been approved for public use, although various recombinant vaccines are undergoing trials and approval for public use is imminent. Therefore, this study aimed to determine the acceptability of and willingness-to-pay for Ebola virus vaccine by the public.MethodsThe study was a community-based cross-sectional qualitative and quantitative interventional study conducted in two communities, each in two states in Nigeria. An interviewer-administered questionnaire was used to collect information on respondents’ knowledge of the Ebola virus, the ways to prevent the disease, and their preventive practices, as well as their acceptability of and willingness-to-pay for a hypothetical vaccine against Ebola virus disease. The association between acceptability of the vaccine and other independent variables were evaluated using multivariate regression analysis.ResultsEbola virus disease was considered to be a very serious disease by 38.5% of the 582 respondents (224/582), prior to receiving health education on Ebola virus and its vaccine. Eighty percent (80%) accepted to be vaccinated with Ebola vaccine. However, among those that accepted to be vaccinated, most would only accept after observing the outcome on others who have received the vaccine. More than 87.5% was willing to pay for the vaccine, although 55.2% was of the opinion that the vaccine should be provided free of charge.ConclusionThe level of acceptability of Ebola virus vaccine among respondents was impressive (though conditional), as well as their willingness to pay for it if the vaccine is not publicly funded. In order to achieve a high uptake of the vaccine, information and education on the vaccine should be extensively shared with the public prior to the introduction of the vaccine, and the vaccine should be provided free of charge by government.  相似文献   

4.
As an emergent infectious disease outbreak unfolds, public health response is reliant on information on key epidemiological quantities, such as transmission potential and serial interval. Increasingly, transmission models fit to incidence data are used to estimate these parameters and guide policy. Some widely used modelling practices lead to potentially large errors in parameter estimates and, consequently, errors in model-based forecasts. Even more worryingly, in such situations, confidence in parameter estimates and forecasts can itself be far overestimated, leading to the potential for large errors that mask their own presence. Fortunately, straightforward and computationally inexpensive alternatives exist that avoid these problems. Here, we first use a simulation study to demonstrate potential pitfalls of the standard practice of fitting deterministic models to cumulative incidence data. Next, we demonstrate an alternative based on stochastic models fit to raw data from an early phase of 2014 West Africa Ebola virus disease outbreak. We show not only that bias is thereby reduced, but that uncertainty in estimates and forecasts is better quantified and that, critically, lack of model fit is more readily diagnosed. We conclude with a short list of principles to guide the modelling response to future infectious disease outbreaks.  相似文献   

5.

Background

A rapid review, guided by a protocol, was conducted to inform development of the World Health Organization’s guideline on personal protective equipment in the context of the ongoing (2013–present) Western African filovirus disease outbreak, with a focus on health care workers directly caring for patients with Ebola or Marburg virus diseases.

Methods

Electronic databases and grey literature sources were searched. Eligibility criteria initially included comparative studies on Ebola and Marburg virus diseases reported in English or French, but criteria were expanded to studies on other viral hemorrhagic fevers and non-comparative designs due to the paucity of studies. After title and abstract screening (two people to exclude), full-text reports of potentially relevant articles were assessed in duplicate. Fifty-seven percent of extraction information was verified. The Grading of Recommendations Assessment, Development and Evaluation framework was used to inform the quality of evidence assessments.

Results

Thirty non-comparative studies (8 related to Ebola virus disease) were located, and 27 provided data on viral transmission. Reporting of personal protective equipment components and infection prevention and control protocols was generally poor.

Conclusions

Insufficient evidence exists to draw conclusions regarding the comparative effectiveness of various types of personal protective equipment. Additional research is urgently needed to determine optimal PPE for health care workers caring for patients with filovirus.  相似文献   

6.
BackgroundFuture infectious disease epidemics are likely to disproportionately affect countries with weak health systems, exacerbating global vulnerability. To decrease the severity of epidemics in these settings, lessons can be drawn from the Ebola outbreak in West Africa. There is a dearth of literature on public perceptions of the public health response system that required citizens to report and treat Ebola cases. Epidemiological reports suggested that there were delays in diagnosis and treatment. The purpose of our study was to explore the barriers preventing Sierra Leoneans from trusting and using the Ebola response system during the height of the outbreak.MethodsUsing an experienced ethnographer, we conducted 30 semi-structured in-depth interviews in public spaces in Ebola-affected areas. Participants were at least age 18, spoke Krio, and reported no contact in the recent 21 days with an Ebola-infected person. We used inductive coding and noted emergent themes.FindingsMost participants feared that calling the national hotline for someone they believed had Ebola would result in that person’s death. Many stated that if they developed a fever they would assume it was not Ebola and self-medicate. Some thought the chlorine sprayed by ambulance workers was toxic. Although most knew there was a laboratory test for Ebola, some erroneously assumed the ubiquitous thermometers were the test and most did not understand the need to re-test in the presence of Ebola symptoms.ConclusionFears and misperceptions, related to lack of trust in the response system, may have delayed care-seeking during the Ebola outbreak in Sierra Leone. Protocols for future outbreak responses should incorporate dynamic, qualitative research to understand and address people’s perceptions. Strategies that enhance trust in the response system, such as community mobilization, may be particularly effective.  相似文献   

7.
An Ebola outbreak of unprecedented scope emerged in West Africa in December 2013 and presently continues unabated in the countries of Guinea, Sierra Leone, and Liberia. Ebola is not new to Africa, and outbreaks have been confirmed as far back as 1976. The current West African Ebola outbreak is the largest ever recorded and differs dramatically from prior outbreaks in its duration, number of people affected, and geographic extent. The emergence of this deadly disease in West Africa invites many questions, foremost among these: why now, and why in West Africa? Here, we review the sociological, ecological, and environmental drivers that might have influenced the emergence of Ebola in this region of Africa and its spread throughout the region. Containment of the West African Ebola outbreak is the most pressing, immediate need. A comprehensive assessment of the drivers of Ebola emergence and sustained human-to-human transmission is also needed in order to prepare other countries for importation or emergence of this disease. Such assessment includes identification of country-level protocols and interagency policies for outbreak detection and rapid response, increased understanding of cultural and traditional risk factors within and between nations, delivery of culturally embedded public health education, and regional coordination and collaboration, particularly with governments and health ministries throughout Africa. Public health education is also urgently needed in countries outside of Africa in order to ensure that risk is properly understood and public concerns do not escalate unnecessarily. To prevent future outbreaks, coordinated, multiscale, early warning systems should be developed that make full use of these integrated assessments, partner with local communities in high-risk areas, and provide clearly defined response recommendations specific to the needs of each community.  相似文献   

8.
As anthropogenic stressors threaten the health of marine ecosystems, there is a need to better understand how the public processes and responds to information about ocean health. Recent studies of public perceptions about ocean issues report high concern but limited knowledge, prompting calls for information campaigns to mobilize public support for ocean restoration policy. Drawing on the literature from communication, psychology and related social science disciplines, we consider a set of social-cognitive challenges that researchers and advocates are likely to encounter when communicating with the public about ocean health and emerging marine diseases—namely, the psychological distance at which ocean issues are construed, the unfamiliarity of aquatic systems to many members of the public and the potential for marine health issues to be interpreted through politicized schemas that encourage motivated reasoning over the dispassionate consideration of scientific evidence. We offer theory-based strategies to help public outreach efforts address these challenges and present data from a recent experiment exploring the role of message framing (emphasizing the public health or environmental consequences of marine disease) in shaping public support for environmental policy.  相似文献   

9.

Background

As Sierra Leone celebrates the end of the Ebola Virus Disease (EVD) outbreak, we can begin to fully grasp its impact on already weak health systems. The EVD outbreak in West Africa forced many hospitals to close down or reduce their activity, either to prevent nosocomial transmission or because of staff shortages. The aim of this study is to assess the potential impact of EVD on nationwide access to obstetric care in Sierra Leone.

Methods and Findings

Community health officers collected weekly data between January 2014—May 2015 on in-hospital deliveries and caesarean sections (C-sections) from all open facilities (public, private for-profit and private non-profit sectors) offering emergency obstetrics in Sierra Leone. This was compared to official data of EVD cases per district. Logistic and Poisson regression analyses were used to compute risk and rate estimates. Nationwide, the number of in-hospital deliveries and C-sections decreased by over 20% during the EVD outbreak. The decline occurred early on in the EVD outbreak and was mainly attributable to the closing of private not-for-profit hospitals rather than government facilities. Due to difficulties in collecting data in the midst of an epidemic, limitations of this study include some missing data points.

Conclusions

Both the number of in-hospital deliveries and C-sections substantially declined shortly after the onset of the EVD outbreak. Since access to emergency obstetric care, like C-sections, is associated with decreased maternal mortality, many women are likely to have died due to the reduced access to appropriate care during childbirth. Future research on indirect health effects of health system breakdown should ideally be nationwide and continue also into the recovery phase. It is also important to understand the mechanisms behind the deterioration so that important health services can be reestablished.  相似文献   

10.
One of the current international public health emergencies is the outbreak of Ebola virus disease (EVD), requiring extraordinary response. The current outbreak in West Africa is the most dangerous since Ebola was first discovered on 26 August 1976. Till January 6th 2015, It resulted in 13,387 laboratory confirmed human cases and 8274 deaths. Ebola virus has 5 strains, 4 are pathogenic in humans while the 5th strain Ebola reston strain is not. The current outbreak is caused by Ebola most pathogenic strain, Ebola Zaire strain whose genome differs from that of Reston Ebola virus strain, by the existence of several open reading frames containing large numbers of UGA codons. These codons act as stop codons and in addition they may encode for Selenocysteine, the 21st aminoacid, which is essential for the formation of Selenoproteins. Selenoproteins are integral to the metabolism and have been linked to the progression of certain viral diseases. In this review, we discuss the relation between Selenium and the progression of the current EVD in Africa supported by geographical distribution of Se and genetic evidence.  相似文献   

11.

Background

Ebolaviruses cause a severe and often fatal haemorrhagic fever in humans, with some species such as Ebola virus having case fatality rates approaching 90%. Currently, the worst Ebola virus outbreak since the disease was discovered is occurring in West Africa. Although thought to be a zoonotic infection, a concern is that with increasing numbers of humans being infected, Ebola virus variants could be selected which are better adapted for human-to-human transmission.

Results

To investigate whether genetic changes in Ebola virus become established in response to adaptation in a different host, a guinea pig model of infection was used. In this experimental system, guinea pigs were infected with Ebola virus (EBOV), which initially did not cause disease. To simulate transmission to uninfected individuals, the virus was serially passaged five times in naïve animals. As the virus was passaged, virulence increased and clinical effects were observed in the guinea pig. An RNAseq and consensus mapping approach was then used to evaluate potential nucleotide changes in the Ebola virus genome at each passage.

Conclusions

Upon passage in the guinea pig model, EBOV become more virulent, RNA editing and also coding changes in key proteins become established. The data suggest that the initial evolutionary trajectory of EBOV in a new host can lead to a gain in virulence. Given the circumstances of the sustained transmission of EBOV in the current outbreak in West Africa, increases in virulence may be associated with prolonged and uncontrolled epidemics of EBOV.  相似文献   

12.

Background

Poverty has been implicated as a challenge in the control of the current Ebola outbreak in West Africa. Although disparities between affected countries have been appreciated, disparities within West African countries have not been investigated as drivers of Ebola transmission. To quantify the role that poverty plays in the transmission of Ebola, we analyzed heterogeneity of Ebola incidence and transmission factors among over 300 communities, categorized by socioeconomic status (SES), within Montserrado County, Liberia.

Methodology/Principal Findings

We evaluated 4,437 Ebola cases reported between February 28, 2014 and December 1, 2014 for Montserrado County to determine SES-stratified temporal trends and drivers of Ebola transmission. A dataset including dates of symptom onset, hospitalization, and death, and specified community of residence was used to stratify cases into high, middle and low SES. Additionally, information about 9,129 contacts was provided for a subset of 1,585 traced individuals. To evaluate transmission within and across socioeconomic subpopulations, as well as over the trajectory of the outbreak, we analyzed these data with a time-dependent stochastic model. Cases in the most impoverished communities reported three more contacts on average than cases in high SES communities (p<0.001). Our transmission model shows that infected individuals from middle and low SES communities were associated with 1.5 (95% CI: 1.4–1.6) and 3.5 (95% CI: 3.1–3.9) times as many secondary cases as those from high SES communities, respectively. Furthermore, most of the spread of Ebola across Montserrado County originated from areas of lower SES.

Conclusions/Significance

Individuals from areas of poverty were associated with high rates of transmission and spread of Ebola to other regions. Thus, Ebola could most effectively be prevented or contained if disease interventions were targeted to areas of extreme poverty and funding was dedicated to development projects that meet basic needs.  相似文献   

13.
In support of the response to the 2013–2016 Ebola virus disease (EVD) outbreak in Western Africa, we investigated the persistence of Ebola virus/H.sapiens-tc/GIN/2014/Makona-C05 (EBOV/Mak-C05) on non-porous surfaces that are representative of hospitals, airplanes, and personal protective equipment. We performed persistence studies in three clinically-relevant human fluid matrices (blood, simulated vomit, and feces), and at environments representative of in-flight airline passenger cabins, environmentally-controlled hospital rooms, and open-air Ebola treatment centers in Western Africa. We also compared the surface stability of EBOV/Mak-C05 to that of the prototype Ebola virus/H.sapiens-tc/COD/1976/Yambuku-Mayinga (EBOV/Yam-May), in a subset of these conditions. We show that on inert, non-porous surfaces, EBOV decay rates are matrix- and environment-dependent. Among the clinically-relevant matrices tested, EBOV persisted longest in dried human blood, had limited viability in dried simulated vomit, and did not persist in feces. EBOV/Mak-C05 and EBOV/Yam-May decay rates in dried matrices were not significantly different. However, during the drying process in human blood, EBOV/Yam-May showed significantly greater loss in viability than EBOV/Mak-C05 under environmental conditions relevant to the outbreak region, and to a lesser extent in conditions relevant to an environmentally-controlled hospital room. This factor may contribute to increased communicability of EBOV/Mak-C05 when surfaces contaminated with dried human blood are the vector and may partially explain the magnitude of the most recent outbreak, compared to prior outbreaks. These EBOV persistence data will improve public health efforts by informing risk assessments, structure remediation decisions, and response procedures for future EVD outbreaks.  相似文献   

14.

Background

Central Africa is a “hotspot” for emerging infectious diseases (EIDs) of global and local importance, and a current outbreak of ebolavirus is affecting multiple countries simultaneously. Ebolavirus is suspected to have caused recent declines in resident great apes. While ebolavirus vaccines have been proposed as an intervention to protect apes, their effectiveness would be improved if we could diagnostically confirm Ebola virus disease (EVD) as the cause of die-offs, establish ebolavirus geographical distribution, identify immunologically naïve populations, and determine whether apes survive virus exposure.

Methodology/Principal findings

Here we report the first successful noninvasive detection of antibodies against Ebola virus (EBOV) from wild ape feces. Using this method, we have been able to identify gorillas with antibodies to EBOV with an overall prevalence rate reaching 10% on average, demonstrating that EBOV exposure or infection is not uniformly lethal in this species. Furthermore, evidence of antibodies was identified in gorillas thought previously to be unexposed to EBOV (protected from exposure by rivers as topological barriers of transmission).

Conclusions/Significance

Our new approach will contribute to a strategy to protect apes from future EBOV infections by early detection of increased incidence of exposure, by identifying immunologically naïve at-risk populations as potential targets for vaccination, and by providing a means to track vaccine efficacy if such intervention is deemed appropriate. Finally, since human EVD is linked to contact with infected wildlife carcasses, efforts aimed at identifying great ape outbreaks could have a profound impact on public health in local communities, where EBOV causes case-fatality rates of up to 88%.  相似文献   

15.
The ability of influenza A viruses (IAVs) to cross species barriers and evade host immunity is a major public health concern. Studies on the phylodynamics of IAVs across different scales – from the individual to the population – are essential for devising effective measures to predict, prevent or contain influenza emergence. Understanding how IAVs spread and evolve during outbreaks is critical for the management of epidemics. Reconstructing the transmission network during a single outbreak by sampling viral genetic data in time and space can generate insights about these processes. Here, we obtained intra-host viral sequence data from horses infected with equine influenza virus (EIV) to reconstruct the spread of EIV during a large outbreak. To this end, we analyzed within-host viral populations from sequences covering 90% of the infected yards. By combining gene sequence analyses with epidemiological data, we inferred a plausible transmission network, in turn enabling the comparison of transmission patterns during the course of the outbreak and revealing important epidemiological features that were not apparent using either approach alone. The EIV populations displayed high levels of genetic diversity, and in many cases we observed distinct viral populations containing a dominant variant and a number of related minor variants that were transmitted between infectious horses. In addition, we found evidence of frequent mixed infections and loose transmission bottlenecks in these naturally occurring populations. These frequent mixed infections likely influence the size of epidemics.  相似文献   

16.
2014年在非洲爆发流行的埃博拉病毒严重威胁人类健康和生命安全,迄今尚未有治疗药物,目前国内外许多医药机构尝试从不同视角发现抗埃博拉病毒的有效药物.本文在对抗流感病毒中药及活性成分进行回顾的基础上提出了抗埃博拉病毒活性化合物的发现策略,为从中药中发现抗埃博拉病毒有效物质提供借鉴和参考.  相似文献   

17.
The current outbreak of Zika virus poses a severe threat to human health. While the range of the virus has been cataloged growing slowly over the last 50 years, the recent explosive expansion in the Americas indicates that the full potential distribution of Zika remains uncertain. Moreover, many studies rely on its similarity to dengue fever, a phylogenetically closely related disease of unknown ecological comparability. Here we compile a comprehensive spatially-explicit occurrence dataset from Zika viral surveillance and serological surveys based in its native range, and construct ecological niche models to test basic hypotheses about its spread and potential establishment. The hypothesis that the outbreak of cases in Mexico and North America are anomalous and outside the native ecological niche of the disease, and may be linked to either genetic shifts between strains, or El Nino or similar climatic events, remains plausible at this time. Comparison of the Zika niche against the known distribution of dengue fever suggests that Zika is more constrained by the seasonality of precipitation and diurnal temperature fluctuations, likely confining autochthonous non-sexual transmission to the tropics without significant evolutionary change. Projecting the range of the diseases in conjunction with three major vector species (Aedes africanus, Ae. aegypti, and Ae. albopictus) that transmit the pathogens, under climate change, suggests that Zika has potential for northward expansion; but, based on current knowledge, our models indicate Zika is unlikely to fill the full range its vectors occupy, and public fear of a vector-borne Zika epidemic in the mainland United States is potentially informed by biased or limited scientific knowledge. With recent sexual transmission of the virus globally, we caution that our results only apply to the vector-borne transmission route of the pathogen, and while the threat of a mosquito-carried Zika pandemic may be overstated in the media, other transmission modes of the virus may emerge and facilitate naturalization worldwide.  相似文献   

18.
Avian influenza viruses (AIVs) have been pivotal to the origination of human pandemic strains. Despite their scientific and public health significance, however, there remains much to be understood about the ecology and evolution of AIVs in wild birds, where major pools of genetic diversity are generated and maintained. Here, we present comparative phylodynamic analyses of human and AIVs in North America, demonstrating (i) significantly higher standing genetic diversity and (ii) phylogenetic trees with a weaker signature of immune escape in AIVs than in human viruses. To explain these differences, we performed statistical analyses to quantify the relative contribution of several potential explanations. We found that HA genetic diversity in avian viruses is determined by a combination of factors, predominantly subtype-specific differences in host immune selective pressure and the ecology of transmission (in particular, the durability of subtypes in aquatic environments). Extending this analysis using a computational model demonstrated that virus durability may lead to long-term, indirect chains of transmission that, when coupled with a short host lifespan, can generate and maintain the observed high levels of genetic diversity. Further evidence in support of this novel finding was found by demonstrating an association between subtype-specific environmental durability and predicted phylogenetic signatures: genetic diversity, variation in phylogenetic tree branch lengths, and tree height. The conclusion that environmental transmission plays an important role in the evolutionary biology of avian influenza viruses—a manifestation of the “storage effect”—highlights the potentially unpredictable impact of wildlife reservoirs for future human pandemics and the need for improved understanding of the natural ecology of these viruses.  相似文献   

19.
Ebola virus infection causes severe hemorrhagic fevers with high fatality rates up to 90% in humans, for which no effective treatment is currently available. The ongoing Ebola outbreak in West Africa that has caused over 14,000 human infections and over 5000 deaths underscores its serious threat to the public health. While licensed vaccines against Ebola virus infection are still not available, a number of vaccine approaches have been developed and shown to protect against lethal Ebola virus infection in animal models. This review aims to summarize the advancement of different strategies for Ebola vaccine development with a focus on the discussion of their protective efficacies and possible limitations. In addition, the development of animal models for efficacy evaluation of Ebola vaccines and the mechanism of immune protection against Ebola virus infection are also discussed.  相似文献   

20.
In 49 patients with known Ebola virus disease outcomes during the ongoing outbreak in Sierra Leone, 13 were coinfected with the immunomodulatory pegivirus GB virus C (GBV-C). Fifty-three percent of these GBV-C+ patients survived; in contrast, only 22% of GBV-C patients survived. Both survival and GBV-C status were associated with age, with older patients having lower survival rates and intermediate-age patients (21 to 45 years) having the highest rate of GBV-C infection. Understanding the separate and combined effects of GBV-C and age on Ebola virus survival may lead to new treatment and prevention strategies, perhaps through age-related pathways of immune activation.  相似文献   

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