London School of Hygiene & Tropical Medicine, London, UK.
Research and Development Institute, National Infection Service, Public Health England, Porton Down, Salisbury, UK.
Lancet Infect Dis. 2019 Apr;19(4):429-438. doi: 10.1016/S1473-3099(18)30791-6. Epub 2019 Feb 21.
To date, epidemiological studies at the index site of the 2013-16 west African Ebola outbreak in Meliandou, Guinea, have been restricted in their scope. We aimed to determine the occurrence of previously undocumented Ebola virus disease (EVD) cases and infections, and to reconstruct transmission events.
This cross-sectional seroprevalence survey of the adult population of Meliandou used a highly specific oral fluid test and detailed interviews of all households in the village and key informants. Each household was interviewed, with all members prompted to describe the events of the outbreak, any illness within the household, and possible contact with suspected cases. Information for deceased individuals was provided by relatives living in the same household. Symptoms were based on Ebola virus Makona variant EVD case definitions (focusing on fever, vomiting, and diarrhoea). For antibody testing, we used an Ebola virus glycoprotein IgG capture enzyme immunoassay developed from a previously validated assay. A maximum exposure level was assigned to every participant using a predetermined scale. We used a generalised linear model (logit function) to estimate odds ratios for the association of sociodemographic variables and exposure level with Ebola virus infection. We adjusted estimates for age and maximum exposure, as appropriate.
Between June 22, and July 9, 2017, we enrolled 237 participants from 27 households in Meliandou. Two households refused to participate and one was absent. All adults in participating households who were present for the interview provided an oral fluid swab for testing, of which 224 were suitable for analysis. In addition to the 11 EVD deaths described previously, on the basis of clinical description and oral fluid testing, we found two probable EVD deaths and eight previously unrecognised anti-Ebola virus IgG-positive survivors, including one who had mild symptoms and one who was asymptomatic, resulting in a case fatality of 55·6% (95% CI 30·8-78·5) for adults. Health-care work (adjusted odds ratio 6·64, 1·54-28·56; p=0·001) and level of exposure (odds ratio adjusted for linear trend across five levels 2·79, 1·59-4·883; p<0·0001) were independent risk factors for infection.
Ebola virus infection was more widespread in this spillover population than previously recognised (21 vs 11 cases). We show the first serological evidence of survivors in this population (eight anti-Ebola virus IgG seropositive) and report a case fatality lower than previously reported (55·6% vs 100% in adults). These data show the high community coverage achievable by using a non-invasive test and, by accurately documenting the beginnings of the west African Ebola virus outbreak, reveal important insight into transmission dynamics and risk factors that underpin Ebola virus spillover events.
US Food and Drug Administration, Wellcome Trust, and German Research Council.
截至目前，在 2013-2016 年西非埃博拉疫情的首发地——几内亚梅利达州进行的流行病学研究，其范围一直受到限制。我们旨在确定以前未记录的埃博拉病毒病（EVD）病例和感染情况，并重建传播事件。
本项针对梅利达州成年人口的横断面血清流行率调查使用了高度特异的口服液检测和对该村所有家庭以及关键知情人的详细访谈。对每个家庭进行访谈，促使所有成员描述疫情爆发期间、家庭内任何疾病以及与疑似病例可能接触的情况。对于已死亡的个体，信息由居住在同一家庭的亲属提供。症状基于埃博拉病毒 Makona 变异 EVD 病例定义（侧重于发热、呕吐和腹泻）。对于抗体检测，我们使用了从先前验证的检测方法开发的埃博拉病毒糖蛋白 IgG 捕获酶免疫测定法。使用预定的量表为每位参与者分配最大暴露水平。我们使用广义线性模型（logit 函数）来估计社会人口统计学变量和暴露水平与埃博拉病毒感染的关联的优势比。我们根据年龄和最大暴露情况，适当调整了估计值。
在 2017 年 6 月 22 日至 7 月 9 日期间，我们从梅利达州的 27 户家庭中招募了 237 名参与者。有两个家庭拒绝参与，一个家庭不在。参与家庭中所有接受访谈且在场的成年人都提供了一份口腔液拭子进行检测，其中 224 份适合分析。除了之前描述的 11 例 EVD 死亡外，根据临床描述和口服液检测，我们发现了两例可能的 EVD 死亡和 8 例以前未识别的抗埃博拉病毒 IgG 阳性幸存者，包括一例症状轻微和一例无症状，导致成年人的病死率为 55.6%（95%CI 30.8-78.5）。卫生保健工作（调整后的比值比为 6.64，1.54-28.56；p=0.001）和暴露水平（调整为五个水平的线性趋势的比值比为 2.79，1.59-4.883；p<0.0001）是感染的独立危险因素。
在此次溢出人群中，埃博拉病毒感染的范围比以前认识到的更为广泛（21 例与 11 例）。我们首次提供了该人群中幸存者的血清学证据（8 例抗埃博拉病毒 IgG 血清阳性），并报告病死率低于以前报告的水平（55.6%对成年人中的 100%）。这些数据表明，使用非侵入性检测可实现高社区覆盖率，并通过准确记录西非埃博拉病毒疫情的开始，深入了解传播动态和风险因素，这些因素是埃博拉病毒溢出事件的基础。
美国食品和药物管理局、惠康信托基金会和德国研究委员会。
