Long-term wildlife mortality surveillance in northern Congo: a model for the detection of Ebola virus disease epizootics

Abstract

Ebolavirus (EBOV) has caused disease outbreaks taking thousands of lives, costing billions of dollars in control efforts and threatening great ape populations. EBOV ecology is not fully understood but infected wildlife and consumption of animal carcasses have been linked to human outbreaks, especially in the Congo Basin. Partnering with the Congolese Ministry of Health, we conducted wildlife mortality surveillance and educational outreach in the northern Republic of Congo (RoC). Designed for EBOV detection and to alert public health authorities, we established a low-cost wildlife mortality reporting network covering 50 000 km². Simultaneously, we delivered educational outreach promoting behavioural change to over 6600 people in rural northern RoC. We achieved specimen collection by training project staff on a safe sampling protocol and equipping geographically distributed bases with sampling kits. We established in-country diagnostics for EBOV testing, reducing diagnostic turnaround time to 3 days and demonstrated the absence of EBOV in 58 carcasses. Central Africa remains a high-risk EBOV region, but RoC, home to the largest remaining populations of great apes, has not had an epidemic since 2005. This effort continues to function as an untested early warning system in RoC, where people and great apes have died from past Ebola virus disease outbreaks. This article is part of the theme issue 'Dynamic and integrative approaches to understanding pathogen spillover'.

Keywords: Ebola spillover; One Health; carcass; community outreach; great ape; surveillance.

Figure 1.

Community-based carcass surveillance network in the RoC. Confirmed EBOV outbreaks in the northern DRC-RoC-Gabon-Cameroon region (large red dots), the villages visited for educational outreach between April 2008–September 2018 (green, n = 268) and the GPS locations of carcasses sampled and analysed for the presence of EBOV (yellow). Protected areas are highlighted in grey. CAR, Central Africa Republic; NNNP, Nouabalé-Ndoki National Park. The sampling station (red circles) distribution reflects partly the accessibility of the terrain. Ouesso base (named, with red circle) can reach the villages south of the base within 1–2 days. Longest distances that our teams have travelled to sample a carcass have been over 200 km from the Ouesso base. In the national parks, carcasses only 30 km away may take over a day to reach. In these areas, the sampling bases have been set up more frequently into the available camps.

Figure 2.

Clockwise from top: deployable complete carcass sampling kit with instructions; teams practice sampling during training; scavenged and decomposed remnants of a week-old juvenile gorilla carcass. (Online version in colour.)