Mortality among PCR negative admitted Ebola suspects during the 2014/15 outbreak in Conakry, Guinea: A retrospective cohort study

Clinical and epidemiological performance of WHO Ebola case definitions: a systematic review and meta-analysis

BACKGROUND

Ebola virus disease case definition is a crucial surveillance tool to detect suspected cases for referral and as a screening tool for clinicians to support admission and laboratory testing decisions at Ebola health facilities. We aimed to assess the performance of the WHO Ebola virus disease case definitions and other screening scores.

METHODS

In this systematic review and meta-analysis, we searched PubMed, Scopus, Embase, and Web of Science for studies published in English between June 13, 1978, and Jan 14, 2020. We included studies that estimated the sensitivity and specificity of WHO Ebola virus disease case definitions, clinical and epidemiological characteristics (symptoms at admission and contact history), and predictive risk scores against the reference standard (laboratory-confirmed Ebola virus disease). Summary estimates of sensitivity and specificity were calculated using bivariate and hierarchical summary receiver operating characteristic (when four or more studies provided data) or random-effects meta-analysis (fewer than four studies provided data).

FINDINGS

We identified 2493 publications, of which 14 studies from four countries (Sierra Leone, Guinea, Liberia, and Angola) were included in the analysis. 12 021 people with suspected disease were included, of whom 4874 were confirmed as positive for Ebola virus infection. Six studies explored the performance of WHO case definitions in non-paediatric populations, and in all of these studies, suspected and probable cases were combined and could not be disaggregated for analysis. The pooled sensitivity of the WHO Ebola virus disease case definitions from these studies was 81·5% (95% CI 74·1-87·2) and pooled specificity was 35·7% (28·5-43·6). History of contact or epidemiological link was a key predictor for the WHO case definitions (seven studies) and for risk scores (six studies). The most sensitive symptom was intense fatigue (79·0% [95% CI 74·4-83·0]), assessed in seven studies, and the least sensitive symptom was pain behind the eyes (1·0% [0·0-7·0]), assessed in three studies. The performance of fever as a symptom varied depending on the cutoff used to define fever.

INTERPRETATION

WHO Ebola virus disease case definitions perform suboptimally to identify cases at both community level and during triage at Ebola health facilities. Inclusion of intense fatigue as a key symptom and contact history could improve the performance of case definitions, but implementation of these changes will require effective collaboration with, and trust of, affected communities.

FUNDING

Médecins sans Frontières.

Pulmonary Involvement during the Ebola Virus Disease

Filoviruses have become a worldwide public health concern, especially during the 2013-2016 Western Africa Ebola virus disease (EVD) outbreak-the largest outbreak, both by number of cases and geographical extension, recorded so far in medical history. EVD is associated with pathologies in several organs, including the liver, kidney, and lung. During the 2013-2016 Western Africa outbreak, Ebola virus (EBOV) was detected in the lung of infected patients suggesting a role in lung pathogenesis. However, little is known about lung pathogenesis and the controversial issue of aerosol transmission in EVD. This review highlights the pulmonary involvement in EVD, with a special focus on the new data emerging from the 2013-2016 Ebola outbreak.

Evaluation of Ebola virus disease surveillance system in Tonkolili District, Sierra Leone

Introduction

The Ebola Virus Disease (EVD) epidemic devastated West Africa, with Sierra Leone recording over 50% of the 28,610 cases across the three most affected countries. Enhanced surveillance system was developed for improved identification of cases and response in Sierra Leone. Here, we evaluated the surveillance system to determine its strengths and challenges in meeting the set objectives.

Methods

The EVD surveillance system in Tonkolili District, Sierra Leone, was assessed using the CDC updated guidelines for evaluating public health surveillance. In particular, the simplicity, stability, acceptability, flexibility, representativeness, sensitivity, positive predictive value and data quality of the system were assessed using EVD surveillance data and information from key informant interviews with program stakeholders.

Results

The EVD surveillance system in Tonkolili District provided information and data on disease trends and outbreak report through official and rumours sources. Case definitions were well understood by participants, with willingness to continue surveillance activities after the EVD outbreak. Standardized data collection tools were in place and data communication was clear with feedback to surveillance units at all levels. The EVD surveillance was not operated within the Integrated Disease Surveillance and Response framework (IDSR). Data completeness was about 91%, consistency existed but data quality was poor (incompletely filled data and missing data existed). Regarding timeliness, samples arrived designated laboratory within 24 - 48 hours in 174 (84.9%). Sensitivity of the surveillance system was 88.5%. Predictive value positive was 25.8%. The stability was questionable since the government of Sierra Leone were not fully in charge of the system.

Conclusion

While the simplicity of the EVD surveillance system in Tonkolili District facilitated its implementation, users suggested that the system did not meet expectations in terms of timeliness, flexibility and acceptability. There was a need to channel efforts towards integrating EVD surveillance into the IDSR. Data completeness and timeliness needed more attention. The District Health Management Team need to take ownership of the surveillance system for sustainability.