RESUMEN
The natural ecology of Ebola virus infection remains enigmatic. No clear reservoir species has been confirmed but there is evidence of infection in a wide spectrum of mammals, including humans, non-human primates, domestic and wild ungulates and a variety of bat species, both frugivorous and insectivorous. Humans and most other species examined appear to be spillover hosts and suffer disease. Bats are the exception and are tolerant to infection in some laboratory studies. Some surveys show a low prevalence of antibodies against Zaire Ebola virus (ZEBOV) strains in bats during human outbreaks and inter-epidemic periods, and this order of mammals is considered to be the likely reservoir for the virus. Other putative sources include insects but this hypothesis is unproven in the field or laboratory. Moreover, some potential sources, such as aquatic species, have yet to be investigated. There are a number of environmental, human behavioural and ecological risk factors proposed with respect to spillover and spread. In the West African outbreak, which was unprecedented in scale and geographic spread, the source of the spillover remains unproven, although an association exists between the proposed index case and a colony of insectivorous bats. In all but a few Ebola virus disease events, spillover has only been superficially investigated and this was also the case in the West African epidemic. The authors suggest that, to address risks at the human-animal-environmental interface, using a One Health approach, more effort is needed to investigate spillover factors at the time of a ZEBOV epidemic, in addition to conducting inter-epidemic surveys in peridomestic environments. The true prevalence of ZEBOV infection in any species of bats remains unknown. Large-scale, expensive, non-randomised surveys, with low sampling numbers per species, are unlikely to provide evidence for Ebola virus reservoirs or to improve our epidemiological understanding.
L'écologie naturelle de l'infection par le virus Ebola demeure énigmatique. Si aucune espèce réservoir au sens strict n'a été clairement identifiée, le virus peut infecter un large spectre d'espèces de mammifères, parmi lesquelles l'être humain, des primates non humains, des ongulés domestiques et sauvages ainsi que de très nombreuses espèces de chauves-souris tant frugivores qu'insectivores. Les humains et la plupart des espèces animales étudiées semblent être des hôtes incidents chez qui la maladie se développe. Les chauves-souris constituent l'exception, certaines études de laboratoire ayant prouvé qu'elles sont tolérantes à l'infection. Des enquêtes ayant montré la présence d'anticorps dirigés contre les souches Zaïre du virus Ebola (Ebola-Zaïre) chez les chauves-souris, à un taux faible de prévalence, pendant les périodes d'activité des foyers chez l'homme ou dans les intervalles inter-épidémiques, cet ordre de mammifères est considéré comme un réservoir possible du virus. Les insectes constituent aussi des sources présumées mais cette hypothèse n'est pas encore démontrée sur le terrain ni même au laboratoire. D'autres sources potentielles doivent encore être étudiées, par exemple parmi les espèces aquatiques. Un certain nombre de facteurs de risque environnementaux, anthropiques et écologiques ont été proposés pour expliquer la transmission entre espèces et la propagation du virus. En ce qui concerne le foyer survenu en Afrique de l'Ouest, sans précédent par son ampleur et par son étendue géographique, la source de la transmission demeure inconnue bien qu'une corrélation ait été observée entre le cas index présumé et la présence d'une colonie de chauves-souris insectivores. Dans pratiquement tous les événements dus au virus Ebola (et l'épidémie en Afrique de l'Ouest ne fait pas exception), l'origine de la transmission n'a guère fait l'objet d'investigations approfondies. Pour que les risques à l'interface humains animauxenvironnement puissent être traités selon la méthode Une seule santé, les auteurs estiment indispensable d'élucider au préalable les facteurs de transmission qui ont pu intervenir lors des épidémies dues au virus Ebola-Zaïre, en plus des enquêtes à effectuer entre deux épidémies et dans un environnement péridomestique. Nous ignorons encore quelle est la prévalence réelle de l'infection par le virus EbolaZaïre chez les chauves-souris, toutes espèces confondues. Il est peu probable que des enquêtes à grande échelle, onéreuses et basées sur des échantillons non aléatoires constitués d'un faible nombre d'individus par espèce parviennent à identifier les réservoirs du virus Ebola ou à améliorer nos connaissances sur son épidémiologie.
La ecología natural de la infección por el virus del Ebola sigue siendo enigmática. No hay especie en la que esté probada una clara función de reservorio, aunque existen datos demostrativos de infección en muy diversos mamíferos, como el ser humano, primates no humanos, ungulados domésticos y silvestres y varias especies de murciélago, tanto frugívoras como insectívoras. El ser humano y la mayoría de las especies estudiadas parecen ser hospedadores no preferentes y padecer la enfermedad, con la única excepción de los murciélagos, que a tenor de ciertos estudios de laboratorio son tolerantes a la infección. En estos animales, algunas investigaciones realizadas sobre el terreno muestran una baja prevalencia de anticuerpos contra cepas de la especie Zaire del virus durante los brotes de infección en el hombre y en los periodos interepidémicos, y se considera probable que este orden de mamíferos sea el reservorio del virus. Se presume que otra fuente podrían ser los insectos, pero ni los datos de laboratorio ni los obtenidos sobre el terreno avalan por ahora tal hipótesis. Además, aún hay otras posibles fuentes por estudiar, como ciertas especies acuáticas. Con respecto a la extensión secundaria y la propagación del virus se han apuntado una serie de posibles factores de riesgo de índole ambiental o ecológica o ligados al comportamiento humano. En el caso del brote habido en África Occidental, que revistió una escala y un alcance geográfico sin precedentes, no se ha demostrado aún cuál fue la fuente de la extensión secundaria, aunque existe una relación entre el caso índice propuesto y una colonia de murciélagos insectívoros. En casi todos los episodios de enfermedad por el virus del Ebola la extensión secundaria se ha investigado solo de forma superficial, como también fue el caso de la epidemia de África Occidental. Los autores sugieren que, para abordar los riesgos existentes en la interfaz del ser humano, los animales y el medio ambiente en clave de Una sola salud, es preciso investigar más a fondo los factores que inducen la extensión secundaria durante una epidemia del virus Zaire del Ebola, además de efectuar estudios del medio peridoméstico en las fases interepidémicas. En ninguna especie de murciélago se conoce aún la verdadera prevalencia de la infección por el virus Zaire. Es poco probable que la realización de onerosos estudios no aleatorizados a gran escala, con la obtención de un pequeño número de muestras por especie, depare indicios sólidos en cuanto a los reservorios del virus del Ebola o nos sirva para entender mejor su epidemiología.
Asunto(s)
Ebolavirus , Fiebre Hemorrágica Ebola , África Occidental/epidemiología , Animales , Quirópteros/virología , Brotes de Enfermedades/prevención & control , Reservorios de Enfermedades , Ebolavirus/fisiología , Fiebre Hemorrágica Ebola/epidemiología , Fiebre Hemorrágica Ebola/virología , HumanosRESUMEN
As of January 3, 2015, Ebola virus disease (Ebola) has killed more than 2,500 persons in Sierra Leone since the epidemic began there in May 2014. Ebola virus is transmitted principally by direct physical contact with an infected person or their body fluids during the later stages of illness or after death. Contact with the bodies and fluids of persons who have died of Ebola is especially common in West Africa, where family and community members often touch and wash the body of the deceased in preparation for funerals. These cultural practices have been a route of Ebola transmission. In September 2014, CDC, in collaboration with the Sierra Leone Ministry of Health and Sanitation (MOH), assessed burial practices, cemetery management, and adherence to practices recommended to reduce the risk for Ebola virus transmission. The assessment was conducted by directly observing burials and cemetery operations in three high-incidence districts. In addition, a community assessment was conducted to assess the acceptability to the population of safe, nontraditional burial practices and cemetery management intended to reduce the risk for Ebola virus transmission. This report summarizes the results of these assessments, which found that 1) there were not enough burial teams to manage the number of reported deaths, 2) Ebola surveillance, swab collection, and burial team responses to a dead body alert were not coordinated, 3) systematic procedures for testing and reporting of Ebola laboratory results for dead bodies were lacking, 4) cemetery space and management were inadequate, and 5) safe burial practices, as initially implemented, were not well accepted by communities. These findings were used to inform the development of a national standard operating procedure (SOP) for safe, dignified medical burials, released on October 1. A second, national-level, assessment was conducted during October 10-15 to assess burial team practices and training and resource needs for SOP implementation across all 14 districts in Sierra Leone. The national-level assessment confirmed that burial practices, challenges, and needs at the national level were similar to those found during the assessment conducted in the three districts. Recommendations based on the assessments included 1) district-level trainings on the components of the SOP and 2) rapid deployment across the 14 districts of additional trained burial teams supplied with adequate personal protective equipment (PPE), other equipment (e.g., chlorine, chlorine sprayers, body bags, and shovels), and vehicles. Although these assessments were conducted very early on in the response, during October-December national implementation of the SOP and recommendations might have made dignified burial safer and increased community support for these practices; an evaluation of this observation is planned.
Asunto(s)
Entierro/métodos , Cementerios , Epidemias/prevención & control , Fiebre Hemorrágica Ebola/prevención & control , Fiebre Hemorrágica Ebola/epidemiología , Humanos , Sierra Leona/epidemiologíaRESUMEN
BACKGROUND: Convalescent blood therapy has been a promising form of treatment for Ebola Virus Disease (EVD), but less attention has been focused on it for treatment. METHOD: We assessed the effectiveness of convalescent whole blood (CWB) in the treatment of consented EVD patients. We recruited 69 subjects in December 2014 up to April 2015, at the 34 Military Hospital in Wilberforce and the PTS 1 Ebola Treatment Unit in Hastings, Freetown. Forty-four were given CWB, and 25 who consented but preferred to be exempted from the CWB treatment were used to compare clinical outcomes. All were given routine treatment used at the Ebola Treatment Unit. RESULTS: One of 44 subjects treated with CWB dropped out of the study and 31 recovered while 12 succumbed to the disease with a case fatality rate of 27.9%. For the group that was given routine treatment without CWB, 11 died with a case fatality rate of 44%. There was a significant difference between admission viral load and viral load after the first 24 h of treatment with convalescent whole blood (P < 0.01). The odds ratio for survival with CWB was 2.3 (95% CI, 0.8-6.5). CONCLUSION: CWB is promising for treating EVD in resource-poor settings, especially in the early phases of outbreaks when resource-mobilization is done. Even though our sample size was small and the evaluation was not randomised, our results contribute to existing evidence that convalescent whole blood could be considered as a useful candidate for treating EVD. Further studies that are randomised will be required to further assess the efficacy of CWB as treatment option during any EVD outbreak.
Asunto(s)
Transfusión Sanguínea , Fiebre Hemorrágica Ebola/terapia , Sueros Inmunes/administración & dosificación , Inmunización Pasiva , Adolescente , Adulto , Niño , Convalecencia , Brotes de Enfermedades , Femenino , Fiebre Hemorrágica Ebola/epidemiología , Fiebre Hemorrágica Ebola/mortalidad , Hospitalización , Humanos , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Sierra Leona/epidemiología , Carga Viral/efectos de los fármacos , Adulto JovenRESUMEN
[This corrects the article DOI: 10.1186/s13017-016-0089-y.].