Feasibility of Xpert Ebola Assay in Médecins Sans Frontières Ebola Program,Guinea

Rapid diagnostic methods are essential in control of Ebola outbreaks and lead to timely isolation of cases and improved epidemiologic surveillance. Diagnosis during Ebola outbreaks in West Africa has relied on PCR performed in laboratories outside this region. Because time between sampling and PCR results can be considerable, we assessed the feasibility and added value of using the Xpert Ebola Assay in an Ebola control program in Guinea. A total of 218 samples were collected during diagnosis, treatment, and convalescence of patients. Median time for obtaining results was reduced from 334 min to 165 min. Twenty-six samples were positive for Ebola virus. Xpert cycle thresholds were consistently lower, and 8 (31%) samples were negative by routine PCR. Several logistic and safety issues were identified. We suggest that implementation of the Xpert Ebola Assay under programmatic conditions is feasible and represents a major advance in diagnosis of Ebola virus disease without apparent loss of assay sensitivity.     

Reemerging Sudan ebola virus disease in Uganda, 2011

Two large outbreaks of Ebola hemorrhagic fever occurred in Uganda in 2000 and 2007. In May 2011, we identified a single case of Sudan Ebola virus disease in Luwero District. The establishment of a permanent in-country laboratory and cooperation between international public health entities facilitated rapid outbreak response and control activities.     

Incubation Period of Ebola Hemorrhagic Virus Subtype Zaire

Objectives

Ebola hemorrhagic fever has killed over 1300 people, mostly in equatorial Africa. There is still uncertainty about the natural reservoir of the virus and about some of the factors involved in disease transmission. Until now, a maximum incubation period of 21 days has been assumed.

Methods

We analyzed data collected during the Ebola outbreak (subtype Zaire) in Kikwit, Democratic Republic of the Congo, in 1995 using maximum likelihood inference and assuming a log-normally distributed incubation period.

Results

The mean incubation period was estimated to be 12.7 days (standard deviation 4.31 days), indicating that about 4.1% of patients may have incubation periods longer than 21 days.

Conclusion

If the risk of new cases is to be reduced to 1% then 25 days should be used when investigating the source of an outbreak, when determining the duration of surveillance for contacts, and when declaring the end of an outbreak.     

Potential mammalian filovirus reservoirs

Ebola and Marburg viruses are maintained in unknown reservoir species; spillover into human populations results in occasional human cases or epidemics. We attempted to narrow the list of possibilities regarding the identity of those reservoir species. We made a series of explicit assumptions about the reservoir: it is a mammal; it supports persistent, largely asymptomatic filovirus infections; its range subsumes that of its associated filovirus; it has coevolved with the virus; it is of small body size; and it is not a species that is commensal with humans. Under these assumptions, we developed priority lists of mammal clades that coincide distributionally with filovirus outbreak distributions and compared these lists with those mammal taxa that have been tested for filovirus infection in previous epidemiologic studies. Studying the remainder of these taxa may be a fruitful avenue for pursuing the identity of natural reservoirs of filoviruses.     

Safety of Recombinant VSV–Ebola Virus Vaccine Vector in Pigs

The ongoing Ebola outbreak in West Africa has resulted in fast-track development of vaccine candidates. We tested a vesicular stomatitis virus vector expressing Ebola virus glycoprotein for safety in pigs. Inoculation did not cause disease and vaccine virus shedding was minimal, which indicated that the vaccine virus does not pose a risk of dissemination in pigs.     

埃博拉出血热的研究进展

埃博拉病毒(ebola virus,EBOV)是传染性疾病埃博拉出血热(ebola hemorrhagic fever,EBHF)的病原体,已在非洲造成多次大规模的暴发流行,死亡率极高。它可通过与患者体液直接接触,或与患者擦伤的皮肤、暴露的黏膜等接触而传染。典型症状及体征主要表现为常规的发热、乏力、肌肉酸痛、头痛、咽喉痛、结膜出血和休克,随后出现呕吐、腹泻、皮疹及多器官功能衰竭等。其致病机制与病毒包膜糖蛋白(viral envelope glycoprotein,GP)有密切的关系。现已制造出使猴群不会被埃博拉病毒感染的疫苗,但尚无对人类有效的疫苗。     

丝状病毒及其相关疾病的研究进展

丝状病毒传染性强,病死率高,主要引起马尔堡出血热和埃博拉出血热,对人类健康危害较大.此文从病原学、流行病学、发病机制、诊断及实验室检查、治疗及预防等方面将两种疾病的研究进展作了综述.     

Ecologic and geographic distribution of filovirus disease

We used ecologic niche modeling of outbreaks and sporadic cases of filovirus-associated hemorrhagic fever (HF) to provide a large-scale perspective on the geographic and ecologic distributions of Ebola and Marburg viruses. We predicted that filovirus would occur across the Afrotropics: Ebola HF in the humid rain forests of central and western Africa, and Marburg HF in the drier and more open areas of central and eastern Africa. Most of the predicted geographic extent of Ebola HF appear to have been observed; Marburg HF has the potential to occur farther south and east. Ecologic conditions appropriate for Ebola HF are also present in Southeast Asia and the Philippines, where Ebola Reston is hypothesized to be distributed. This first large-scale ecologic analysis provides a framework for a more informed search for taxa that could constitute the natural reservoir for this virus family.