The basic reproductive number of Ebola and the effects of public health measures: the cases of Congo and Uganda

Despite improved control measures, Ebola remains a serious public health risk in African regions where recurrent outbreaks have been observed since the initial epidemic in 1976. Using epidemic modeling and data from two well-documented Ebola outbreaks (Congo 1995 and Uganda 2000), we estimate the number of secondary cases generated by an index case in the absence of control interventions R0. Our estimate of R0 is 1.83 (SD 0.06) for Congo (1995) and 1.34 (SD 0.03) for Uganda (2000). We model the course of the outbreaks via an SEIR (susceptible-exposed-infectious-removed) epidemic model that includes a smooth transition in the transmission rate after control interventions are put in place. We perform an uncertainty analysis of the basic reproductive number R0 to quantify its sensitivity to other disease-related parameters. We also analyse the sensitivity of the final epidemic size to the time interventions begin and provide a distribution for the final epidemic size. The control measures implemented during these two outbreaks (including education and contact tracing followed by quarantine) reduce the final epidemic size by a factor of 2 relative the final size with a 2-week delay in their implementation.     

Community-Centered Responses to Ebola in Urban Liberia: The View from Below

BackgroundThe West African Ebola epidemic has demonstrated that the existing range of medical and epidemiological responses to emerging disease outbreaks is insufficient, especially in post-conflict contexts with exceedingly poor healthcare infrastructures. In this context, community-based responses have proven vital for containing Ebola virus disease (EVD) and shifting the epidemic curve. Despite a surge in interest in local innovations that effectively contained the epidemic, the mechanisms for community-based response remain unclear. This study provides baseline information on community-based epidemic control priorities and identifies innovative local strategies for containing EVD in Liberia.Conclusions/SignificanceLocal communities’ strategies and recommendations give insight into how urban Liberian communities contained the EVD outbreak while navigating the systemic failures of the initial state and international response. Communities in urban Liberia adapted to the epidemic using multiple coping strategies. In the absence of health, infrastructural and material supports, local people engaged in self-reliance in order to contain the epidemic at the micro-social level. These innovations were regarded as necessary, but as less desirable than a well-supported health-systems based response; and were seen as involving considerable individual, social, and public health costs, including heightened vulnerability to infection.     

Community trust of government and non-governmental organizations during the 2014-16 Ebola epidemic in Liberia

The West African Ebola Virus Disease epidemic of 2014-16 cost more than 11,000 lives. Interventions targeting key behaviors to curb transmission, such as safe funeral practices and reporting and isolating the ill, were initially unsuccessful in a climate of fear, mistrust, and denial. Building trust was eventually recognized as essential to epidemic response and prioritized, and trust was seen to improve toward the end of the epidemic as incidence fell. However, little is understood about how and why trust changed during Ebola, what factors were most influential to community trust, and how different institutions might have been perceived under different levels of exposure to the outbreak. In this large-N household survey conducted in Liberia in 2018, we measured self-reported trust over time retrospectively in three different communities with different exposures to Ebola. We found trust was consistently higher for non-governmental organizations than for the government of Liberia across all time periods. Trust reportedly decreased significantly from the start to the peak of the epidemic in the study site of highest Ebola incidence. This finding, in combination with a negative association found between knowing someone infected and trust of both iNGOs and the government, indicates the experience of Ebola may have itself caused a decline of trust in the community. These results suggest that national governments should aim to establish trust when engaging communities to change behavior during epidemics. Further research on the relationship between trust and epidemics may serve to improve epidemic response efficacy and behavior uptake.     

Primates and pandemics: A biocultural approach to understanding disease transmission in human and nonhuman primates

Investigations into zoonotic disease outbreaks have been largely epidemiological and microbiological, with the primary focus being one of disease control and management. Increasingly though, the human–animal interface has proven to be an important driver for the acquisition and transmission of pathogens in humans, and this requires syncretic bio-socio-cultural enquiries into the origins of disease emergence, for more efficacious interventions. A biocultural lens is imperative for the examination of primate-related zoonoses, for the human-primate interface is broad and multitudinous, involving both physical and indirect interactions that occur due to shared spaces and ecologies. I use the case example of a viral zoonotic epidemic that is currently endemic to India, the Kysanaur Forest Disease, to show how biocultural anthropology provides a broad and integrative perspective into infectious disease ecology and presents new insights into the determinants of disease outbreaks. Drawing on insights from epidemiology, political ecology, primate behavioral ecology and ethnoprimatology, this paper demonstrates how human-primate interactions and shared ecologies impact infectious disease spread between human and nonhuman primate groups.     

丝状病毒出血热的血清流行病学调查研究及现状

丝状病毒(包括马尔堡与埃波拉病毒)被发现已有40余年,对其自然流行病学尚不清楚。综述了该病血清流行病学调查结果,丝状病毒出现的频率,地理生态学分布,及病毒生物学特性,为该病流行因素提供了信息与框架。然而,对病毒宿主,传入人类的起源、地理分布、具体区域等流行生态学有待进一步研究。     

埃博拉病毒/埃博拉病—2014

2014年2月,死亡率极高的埃博拉病(EVD)开始在西部非洲的几内亚暴发流行,接下来,暴发流行出现在塞拉利昂、利比里亚、尼日利亚和塞内加尔另四个西部非洲的国家。现在,几内亚、利比里亚和塞拉利昂的疫情最重。迄今为止,已有4 784人患EVD,且人数仍在倍增,这次暴发流行已成为自40年前EVD被发现以来规模最大的一次,已形成了波及其他地区和国家的巨大危险。在此,综述2014年EVD暴发流行的起因,埃博拉病毒(EBOV)及其传播,EVD的诊断治疗,EBOV疫苗的研制以及EBOV感染的防控。     

The Power of Environmental Knowledge: Ethnoecology and Environmental Conflicts in Mexican Conservation

Theory in political ecology emphasizes the role of competing interests in shaping resource use. Although supportive of these approaches, this article draws on the importance of meanings assigned to ecological systems to question how epistemological differences also contribute to environmental conflicts. Following calls to examine the interface between environmental knowledge and action, consideration is given to ethnoecological constructs of forests on Mexico's southern Yucatan peninsula, home to the Calakmul Biosphere Reserve. To quiet opposition to the Reserve, government agents increased financial aid to the region in the form of conservation development projects. With the counsel of a Reserve director, local residents effectively used these projects to press for an environmentalism based on sustainable resource use. This position has associations with a local ethnoecology of land as a place of work. In examining how ethnoecologies played out in contests surrounding conservation, possibilities for a localized, alternative environmentalism are discussed, as well as the importance of environmental constructs for research in political ecology.     

The politics of pathology: how obesity became an epidemic disease

Americans' recent weight gains have been widely described as an "obesity epidemic." Such a characterization, however, has many problems: the average American weight gain has been relatively low (eight to 12 pounds over the last 20 years), and the causal linkages between adiposity, morbidity, and mortality are unclear. Nevertheless, the media and numerous health officials continue to sound dire warnings that obesity has become an epidemic disease. In this article, I examine how and why America's growing weight became an "obesity epidemic." I find the disease characterization has less to do with the health consequences of excess weight and more with the various financial and political incentives of the weight loss industry, medical profession, and public health bureaucracy. This epidemic image was also assisted by the method of displaying information about weight gain with maps in PowerPoint slides. Such characterizations, I argue, are problematic. Given the inconclusive scientific evidence and the absence of a safe and effective weight loss regimen, calling America's growing weight an epidemic disease is likely to cause more harm than good.     

中国埃博拉诊疗中心布局流程的设计与思考

为了应对西非埃博拉病毒病疫情,中国人民解放军援利医疗队在利比里亚建立并独立运营了埃博拉诊疗中心。中心严格按照传染病医院的防护要求和标准,设计科学合理的布局流程,实现有效的感染防控。详细说明了中国埃博拉诊疗中心的布局与流程设计,归纳阐述其特点,并对做好布局流程应把握的几个重点问题进行了探讨。     

Unusually severe symptoms are a characteristic of the current epidemic of mosaic virus disease of cassava in Uganda

Mosaic disease (MD) is more severe in cassava plants infected within the area of the current epidemic in northern and central Uganda than to the south of the affected area. This difference in severity was recorded within a single cultivar as well as amongst the mixtures of cultivars found commonly in farmers' fields. An increase in severity also occurred as the epidemic passed through localities. Varietal or agroecological factors coincident with the area of the epidemic are therefore unlikely to cause the increased severity. The severe disease could also be graft and cutting transmitted and could super-infect mildly diseased plants. Both mildly and severely diseased plants gave positive reactions in ELISA tests to antisera prepared against African cassava mosaic virus (ACMV) and an unusually severe form of ACMV or a closely related geminivirus is likely to be the cause of the severe mosaic disease. The epidemic also involves increased populations of the whitefly vector of ACMV, Bemisia tabaci , and possible hypotheses are presented as to how these phenomena may be related.     

The ecology of Ebola virus

Since Ebola virus was first identified more than 30 years ago, tremendous progress has been made in understanding the molecular biology and pathogenesis of this virus. However, the means by which Ebola virus is maintained and transmitted in nature remains unclear despite dedicated efforts to answer these questions. Recent work has provided new evidence that fruit bats might have a role as a reservoir species, but it is not clear whether other species are also involved or how transmission to humans or apes takes place. Two opposing hypotheses for Ebola emergence have surfaced; one of long-term local persistence in a cryptic and infrequently contacted reservoir, versus another of a more recent introduction of the virus and directional spread through susceptible populations. Nevertheless, with the increasing frequency of human filovirus outbreaks and the tremendous impact of infection on the already threatened great ape populations, there is an urgent need to better understand the ecology of Ebola virus in nature.     

Sustaining ignorance: the uncertainties of groundwater and its extraction in the Salar de Atacama,northern Chile

The extraction of groundwater and the regulation of its use in many parts of the world have been found to present a particular kind of problem. A contest involving mining companies, an ‘impacted’ community, and the state arising from groundwater and its extraction in the Salar de Atacama, northern Chile, provides a stark example. What marks the case are the many uncertainties about underground water and the quantities extracted. This article argues that uncertainty characterizes conditions of ‘late industrialism’ and that corporate practice that sustains ignorance is a form of powerful agency that in turn maintains the conditions for potentially harmful extractive activity. Critically engaging with the proposition that water may act in the relational process of unknowing contributes to the analysis of how corporate practice may sustain ignorance. This also suggests that alternative political responses to uncertainty are possible.     

Health seeking behavior after the 2013–16 Ebola epidemic: Lassa fever as a metric of persistent changes in Kenema District,Sierra Leone

BackgroundThe West African Ebola epidemic of 2013–2016 killed nearly 4,000 Sierra Leoneans and devastated health infrastructure across West Africa. Changes in health seeking behavior (HSB) during the outbreak resulted in dramatic underreporting and substantial declines in hospital presentations to public health facilities, resulting in an estimated tens of thousands of additional maternal, infant, and adult deaths per year. Sierra Leone’s Kenema District, a major Ebola hotspot, is also endemic for Lassa fever (LF), another often-fatal hemorrhagic disease. Here we assess the impact of the West African Ebola epidemic on health seeking behaviors with respect to presentations to the Kenema Government Hospital (KGH) Lassa Ward, which serves as the primary health care referral center for suspected Lassa fever cases in the Eastern Province of Sierra Leone.Methodology/Principal findingsPresentation frequencies for suspected Lassa fever presenting to KGH or one of its referral centers from 2011–2019 were analyzed to consider the potential impact of the West African Ebola epidemic on presentation patterns. There was a significant decline in suspected LF cases presenting to KGH following the epidemic, and a lower percentage of subjects were admitted to the KGH Lassa Ward following the epidemic. To assess general HSB, a questionnaire was developed and administered to 200 residents from 8 villages in Kenema District. Among 194 completed interviews, 151 (78%) of respondents stated they felt hospitals were safer post-epidemic with no significant differences noted among subjects according to religious background, age, gender, or education. However, 37 (19%) subjects reported decreased attendance at hospitals since the epidemic, which suggests that trust in the healthcare system has not fully rebounded. Cost was identified as a major deterrent to seeking healthcare.Conclusions/SignificanceAnalysis of patient demographic data suggests that fewer individuals sought care for Lassa fever and other febrile illnesses in Kenema District after the West African Ebola epidemic. Re-establishing trust in health care services will require efforts beyond rebuilding infrastructure and require concerted efforts to rebuild the trust of local residents who may be wary of seeking healthcare post epidemic.     

Acceptability and Willingness-to-Pay for a Hypothetical Ebola Virus Vaccine in Nigeria

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.     

Ebola in great apes – current knowledge,possibilities for vaccination,and implications for conservation and human health

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Phylogeography, hybridization and Pleistocene refugia of the kob antelope (Kobus kob)

Mitochondrial DNA control region sequences and seven microsatellites were used to estimate the genetic structuring, evolutionary history and historic migration patterns of the kob antelope (Kobus kob). Ten populations were analysed, representing the three recognized K. kob subspecies: K. k. kob in west Africa, K. k. thomasi in Uganda and K. k. leucotis in Sudan and Ethiopia. Despite being classified as K. k. thomasi and being phenotypically identical to the kob in Queen Elizabeth National Park (NP), the Murchison Falls population in Uganda showed high genetic similarity with the phenotypically distinct K. k. leucotis populations in Sudan and Ethiopia. This was regardless of marker type. Pairwise comparisons and genetic distances between populations grouped Murchison with K. k. leucotis, as did the Bayesian analysis, which failed to find any genetic structuring within the group. We propose that the divergent phenotype and life-history adaptations of K. k. leucotis reflect the isolation of kob populations in refugia in west and east Africa during the Pleistocene. Subsequent dispersal has led to secondary contact and hybridization in northern Uganda between lineages, which was supported by high levels of genetic diversity in Murchison. The reduced variability observed in Queen Elizabeth NP reflects a small founder population from west Africa and in part the decimation of Uganda's wildlife during the country's political turmoil in the 1970s. Due to similarities in phenotype and ecology, and the joint evolutionary history of their mtDNA sequences, the taxonomic status of K. k. kob and K. k. thomasi as separate subspecies is called into question.     

A participatory epidemiological and One Health approach to explore the community’s capacity to detect emerging zoonoses and surveillance network opportunities in the forest region of Guinea

The Ebola virus disease epidemic that threatened West Africa between 2013 and 2016 was of unprecedented health magnitude. After this health crisis, studies highlighted the need to introduce community-based surveillance systems and to adopt a One Health approach. This study aimed to provide preparatory insights for the definition of a community-based surveillance system for emerging zoonoses such as viral hemorrhagic fevers in Guinea. The objective was to explore the disease detection capacity and the surveillance network opportunities at the community level in two pilot areas in the forest region of Guinea, where the epidemic emerged. Based on a participatory epidemiological and One Health approach, we conducted Focus Group Discussions with human, animal and ecosystem health actors. We used a range of participatory tools, included semi-structured interviews, ranking, scoring and flow diagram, to estimate the local knowledge and perception of diseases and clinical signs and to investigate the existing health information exchange network and its related strengths and weaknesses. The results showed that there is heterogeneity in knowledge of diseases and perception of the clinical signs among actors and that there are preferred and more effective health communication channels opportunities. This preparatory study suggests that it is necessary to adapt the case definitions and the health communication channels to the different actors who can play a role in a future community-based surveillance system and provides recommendations for future surveillance activities to be carried out in West Africa.     

The 1901 uganda sleeping sickness epidemic revisited: a case of mistaken identity?

The great sleeping sickness epidemic that occurred in Busoga at the turn of the century was caused by a trypanosome identified by Bruce as Trypanosoma gambiense. A study of trypanosomes from the recent epidemic in southeast Uganda has shed new light on the origins of the disease in Busoga. Thorsten Koerner, Peter de Raadt and Ian Maudlin suggest that the epidemic of the turn of the century was of T. p. rhodesiense sleeping sickness, brought about then, as now by social upheaval.     

Evaluating Subcriticality during the Ebola Epidemic in West Africa

The 2014–2015 Ebola outbreak is the largest and most widespread to date. In order to estimate ongoing transmission in the affected countries, we estimated the weekly average number of secondary cases caused by one individual infected with Ebola throughout the infectious period for each affected West African country using a stochastic hidden Markov model fitted to case data from the World Health Organization. If the average number of infections caused by one Ebola infection is less than 1.0, the epidemic is subcritical and cannot sustain itself. The epidemics in Liberia and Sierra Leone have approached subcriticality at some point during the epidemic; the epidemic in Guinea is ongoing with no evidence that it is subcritical. Response efforts to control the epidemic should continue in order to eliminate Ebola cases in West Africa.