Postmortem Surveillance for Ebola Virus Using OraQuick Ebola Rapid Diagnostic Tests, Eastern Democratic Republic of the Congo, 2019–2020

After a pilot study, we tested 443 cadavers using OraQuick Ebola rapid diagnostic tests during surveillance after the 10th Ebola outbreak in the Democratic Republic of the Congo. No false negative and 2% false-positive results were reported. Quickly returning results and engaging the community enabled timely public health actions.

Health Organization have recommended its use for testing cadaver fluids of suspected EVD patients (9). Ethics approval and participant consent were not deemed necessary because specimens were collected for outbreak response and data were de-identified before analysis. A consortium of laboratory, epidemiology, communication, and community engagement professionals, led by the DRC Ministry of Health, formed an RDT technical working group to coordinate field implementation, including SDBs, community engagement, and data collection. A steering committee composed of senior leaders from the Institut National de Recherche Biomédicale (INRB) and international partners advised the RDT Working Group.
The Lessons learned from the pilot study included the need for better community engagement, improved data collection and reporting, and more indepth healthcare worker training. After the pilot study, RDT postepidemic (August 1-October 31, 2020) surveillance was conducted on cadavers in 19 health areas of the Beni health zone (Figure 1), the last health zone affected during the outbreak. RDTs were administered by 32 teams of locally trained healthcare workers, each composed of a laboratorian or nurse, a hygienist, a community engagement specialist, and a supervisor. The laboratorian/nurse collected 1 swab sample with the pad of the OraQuick device for the RDT and stored another swab sample in viral transport medium for quantitative RT-PCR confirmation. The hygienist oversaw biosafety practices and ensured that biologic waste (used RDT kits and personal protective equipment) was properly incinerated. A community engagement specialist communicated with the family, provided psychosocial support, and engaged the community using media and interactions with local leaders. The supervisor assumed responsibility for RDT quality control. Field teams were provided with the testing algorithm ( Figure 2), a field training manual, and communication materials to assist with community engagement. SDB teams were on standby for safe burials as requested by families or if a sample was reactive/invalid.
Data were collected using tablets outfitted with a free, open-source, Kobo-based mobile data collection tool (https://www.humanitarian response.info/fr/ applications/kobotoolbox), developed for this purpose using a set of 75 questions in French. The data collection tool operated offline. RDT data, collection site geolocations, and photographs of RDT results were transmitted daily to the Kobo server when inter- net connection was available. A dashboard displaying key indicators was updated automatically twice a day. We used R software (10) to assess the diagnostic accuracy of the RDTs, using quantitative RT-PCR results as the standard. After receiving permission from decedents' families, the laboratorian/nurse hygienist performed the test following instructions in the manual (S2). Results were read, interpreted, and photographed at 30 minutes, according to the manufacturer's instructions. If the RDT was nonreactive, families could proceed with traditional burial. If the RDT was reactive or invalid, the sample in viral transport medium, packaged in cooler boxes with ice packs, was transported immediately to an INRB lab for confirmation by GeneXpert Ebola quantitative RT-PCR (Cepheid, https://www. cepheid.com), with result turnaround time under 24 hours. An RDT was considered invalid when, after 1 repeat, no line appeared in the C area of the test, a purple background obscured the results, or a partial line appeared in the C or T area after 30 minutes.

Conclusions
Trained local healthcare workers successfully used OraQuick Ebola RDTs for enhanced postmortem surveillance after the 10th EVD outbreak in DRC. Molecular testing revealed no false-negative RDT results, suggesting that quick public health actions can be based on RDT results alone. The low cycle thresholds observed in positive samples during the pilot study (Appendix Table, https://wwwnc.cdc.gov/ EID/article/28/2/21-0981-App1.pdf) support using RDTs in cadavers, in which viral loads are expected to be high (11)(12)(13). Our study shows that RDTs can detect EVD-related deaths and reduce the risk for community transmission. The utility of this tool in EVD surveillance is supported by recent observations that SDBs were not conducted during early stages of recent EVD resurgences in North Kivu and Guinea (CDC 2021 Ebola Response, unpub. data).
In conclusion, postmortem OraQuick Ebola RDTs effectively complemented outbreak-response efforts, improved community trust, and decreased the number of SDBs. However, the reported 2% false-positive tests required further confirmation and were not immediately actionable. SDBs requested by families despite nonreactive RDT further highlight the need for further community engagement.

About the Authors
Dr. Sanogo is a microbiologist and epidemiologist in the Emergency Response and Recovery Branch (Global Rapid Response Team), Division of Global Health Protection, Center for Global Health, Centers for Disease Control and Prevention. His research interests encompass laboratory diagnostics of emerging pathogens, including vectorborne diseases, hemorrhagic fever viruses, next-generation sequencing, and strengthening laboratory capacity in resource-limited countries. Dr. Mukadi is a physician and medical virologist at the Institut National de Recherche Biomédicale in Kinshasa, DRC. His expertise includes setup and coordination of field laboratories in response to Ebola outbreaks and evaluation of rapid diagnostic tests.