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Epidemiological Overview of the 10th Ebola outbreak in the Democratic Republic of the Congo, May 2018 – May 2020

Background: The 10th Ebola virus disease (EVD) outbreak was the longest and widest EVD outbreak experienced by the Democratic Republic of the Congo. More than forty national and international partners supported the response under the overall leadership of the Ministry of Health (MoH) with the support of the World Health Organization (WHO). Several innovations were brought to the response arsenal to support prevention, surveillance, and case management. We summarise key epidemiological features and surveillance operations deployed during this outbreak. 
 
Methods: Alert, suspected, probable, and confirmed case definitions were adapted by the MoH from WHO guidelines. All alerts were generated through passive and active notifications and further investigated using a standardised investigation form. Laboratory confirmation was conducted using GeneXpert Ebola assay on whole blood or buccal swabs. Data were captured using the EpiInfo-VHF application, supplemented by other datasets. 
 
Findings: Over the course of the outbreak, 981121 alerts were reported requiring investigation, isolation, specialized care, and laboratory testing. A total of 3481 cases were recorded in 211 health areas of 29 health zones of three provinces, including five cases exported to Kasese District, Uganda. The overall case-fatality ratio was 66% (2299/3461) and a third (33%) of all cases died outside of a treatment centre. Although, 87% of contacts were followed for 21 days, almost half (48%) of all cases were not registered contacts at time of detection. 
 
Interpretation: The response relied highly upon the surveillance teams’ capacity to detect and investigate thoroughly incident cases in order to identify chains of transmission and prevent further spread of the disease. The improvement of contact tracing indicators was followed by decreased delays to admission and improved outcome. Lessons learned from this outbreak will be essential to guide future responses to future EVD outbreaks by leveraging new tools implemented during this epidemic. 
 
Funding: None 
 
Declaration of Interest: None