Wild meat consumption is common in Southeast Asia, and can result in virus spillover to humans. It was probably in this region that the SARS-CoV-2 virus behind the Covid-19 pandemic originated.
It was these issues, and more precisely the surveillance and early detection of pathogens hosted by wildlife that the ZooCov project, coordinated by CIRAD, studied for a year and a half in Cambodia.
The goal of the ZooCov project is to produce new knowledge about wildmeat distribution and consumption chains in Cambodia, establish an inventory of the diversity of beta-CoVs circulating through these chains, and develop an integrated system to monitor the risk of beta-CoV transmission to humans.
Combining animal, human and environmental health questions
ZooCov was launched right at the start of the pandemic, with funding from the Agence nationale de la recherche and the Occitanie Regional Council, and focused on four lines of research:
- Identifying and analysing the main wildlife trade chains in two pilot areas;
- Analysing wild meat consumption practices;
- the diversity of betacoronaviruses in wild meat and in certain bat and rodent colonies in the study areas;
- human exposure to those betacoronaviruses;
- predictors of that human exposure to betacoronaviruses;
- Developing a methodological framework to incorporate early detection of viral spillover events.
Two years on, the project has delivered its results.
The first success is the concrete implementation of the One Health approach, which consists in tackling animal health, human health and environmental health issues simultaneously. This type of approach will serve to build disease emergence prevention strategies, notably against zoonotic diseases, before humans begin to be affected.
This work was facilitated by the support received from the three Cambodian ministries concerned: Agriculture, Environment, and Health. That support made it possible to build international collaboration between the 17 project partners – research organizations, NGOs, universities, private institutes, etc. – working in the fields of ecology, conservation, the social sciences, epidemiology and virology*.
Samples taken from more than 2100 animals and 1000 people
It was within that multidisciplinary framework that the teams involved worked to describe local commercial supply chains. The scientists identified the main species hunted and consumed, the pathogens in circulation, and the people in closest contact with animals, hence at greatest risk of being infected.
They took samples from more than 2100 animals – rodents, civet cats, monkeys, bats, deer, etc. The samples were then tested for coronaviruses, and 24 proved positive (1.1%), some of them for viruses similar to SARS-CoV2.
An initiative to assess coronavirus circulation patterns in several bat species found in Cambodia has revealed opportunities for the early detection of infection outbreaks in these animals – with the long-term goal of safeguarding biodiversity and containing spillover to humans.
At the same time, samples were taken from more than 1000 people to quantify their exposure to those pathogens. Sociological surveys were also done to ask those people about their consumption and hunting practices and what motivated or restricted those practices.
Including a sociological approach, one of the key elements of the project
The inclusion of social sciences right from the start of the project is another of its successes, which served to build a substantial anthropology component.
Thanks to the surveys, the project now has results on how local people see the wild meat trade and the risks to which they are exposed, and on how the Covid-19 crisis has affected hunting and/or consumption practices.
For instance, in one of the provinces studied, where 107 households were visited, 77% of people declared that they had eaten wild meat in the past month. In another zone, almost 80% of people were in contact with and exposed to wildlife during a range of activities: wildlife hunting, wild meat consumption and sales, or their work as rangers or foresters.
Those figures will serve to anchor the future integrated surveillance network for which CIRAD and its partners have already laid the foundations, in line with the One Health approach. "We based ourselves on a wildlife surveillance network led by the WCS", says Véronique Chevalier, a veterinarian from CIRAD who coordinated the project. "We assessed the sensitivity of the network, in other words its ability to detect pathogen circulation."
Lastly, the team looked at the legal framework regulating the trade in Cambodia, and the position of the various players – rangers, traders, the authorities, and also consumers and hunters – in relation to that framework. This was intended to improve the adoption, acceptability and sustainability of surveillance.
Results that pave the way for large-scale projects
The project team is now looking into various possibilities of improvement. To this end, they are using the data concerning the people most at risk and the seasons in which betacoronavirus circulation peaks.
One possible improvement would be to combine this wildlife surveillance network with so-called "syndromic" human health surveillance, in other words based on detecting general symptoms such as fever or coughing.
Other prospects such as ecological surveillance or active blood testing of wild and/or domestic animals will be assessed by wider-ranging projects based, among other things, on ZooCov's results.
The BCOMING project, in particular, intends to look at biodiversity conservation as a way of reducing the risks of infectious disease emergence. It will be funded by the Horizon Europe programme, with a budget of 6 million euros, and is to be coordinated by CIRAD.
* CIRAD's partners in the ZooCov project
- BirdLife International
- Cambodia Disease Control Center
- Centre Nationale de la Recherche Scientifique (CNRS)
- Collège de France
- Elephant Livelihood Initiative Environment (ELIE)
- Flora and Fauna International (FFI)
- Hong Kong University (HKU)
- Institut Pasteur of Cambodia (IPC)
- Institut de Recherche pour le Développement (IRD)
- International Development Enterprise (iDE)
- Jahoo, World Hope International
- Ministry of Agriculture, Forests and Fisheries Resources, Cambodia
- Ministry of the Environment, Cambodia
- Ministry of Health, Cambodia
- GREASE network
- Wildlife Conservation Society (WCS)
- World Wild Fund for Nature (WWF)