In the last century, a combination of population growth and reduction in ecosystems and biodiversity has created unprecedented opportunities for zoonotic diseases - where pathogens pass between animals and people. In 2016, the United Nations Environment Programme (UNEP) and the International Livestock Research Institute (ILRI) flagged a worldwide increase in zoonotic epidemics.
This year, with the outbreak of COVID-19 having affected every country in the world, UNEP and researchers from the International Livestock Research Institute have conducted a scientific assessment to consolidate knowledge and identify areas of policy focus. Titled Preventing the Next Pandemic: zoonotic diseases and how to break the chain of transmission, the assessment is to be published in July.
In advance of World Environment Day (5 June), UNEP Chief of Wildlife, Doreen Robinson and Professor of Veterinary Infectious Diseases at the University of Liverpool, Eric Fèvre discuss how we might prevent and manage zoonotic diseases in the future.
What is the connection between zoonotic diseases and biodiversity?
Robinson: The relationship between the environment and the emergence and spread of disease is very complex. In the last century, our environment has changed tremendously: population growth and associated altering of land for settlements, agriculture, logging, extractive industries or other uses has led to habitat and biodiversity loss. This has created many opportunities for pathogens to pass between animals and people as the natural buffers between humans and animals have disappeared. We also know that higher levels of native biodiversity has been associated with reduced transmission of some zoonotic diseases.
Changes in temperature, humidity and seasonality directly affect the survival of microbes in the environment. As we alter habitats, we change these conditions. Evidence suggests that disease epidemics will become more frequent, as the climate continues to change. We also cannot forget that biological diversity is one of humanity’s greatest sources of medicine and treatments. By stopping biodiversity loss and investing in a planetary health, we safeguard human health.
Coronavirus transmission has been associated with traditional wet markets. Does this mean that wet markets should be banned?
Fèvre: The term “wet market” is sometimes misunderstood and laden with judgment. What are referred to as wet markets are really just a type of fresh food market. Selling low volume fresh food is also an essential way in which millions–perhaps billions–of people access affordable food on a day to day basis. To consider banning them would ignore their essential role in food security and in providing livelihoods to the people who supply them, often through informal market systems. More importantly, we might think about how they are managed; provide support and, where needed, legislation that ensures environments are more propitious to food safety and public health.
A related–but distinct–issue is the sale of wildlife products in such environments. It is important to ensure that illegal wildlife products are not sold in these markets, and this requires improved trade legislation and enforcement in some cases. However, preventing the sale of illegal wildlife should not be confused with banning the existence of the market itself.
The impact of COVID-19 has varied from one country to another. Why is this?
Fèvre: Populations in different countries and regions behave and interact differently and have different demographic characteristics. In sub-Saharan Africa, for example, urban populations tend to be dominated by younger age groups, compared to cities in Europe. Social and economic interactions also vary, such that contact networks between people will exhibit very different patterns. And some regions of the world are far less globally connected than others, meaning fewer infected people entering those populations. Certain countries also took action to reduce the risk of transmission much earlier than others, preventing the early, rapid and silent spread of COVID-19 that occurred elsewhere.
COVID-19 is just one in a long string of coronaviruses to have broken out in recent decades. Should we accept them as the new normal, or is there something we can do to prevent them?
Fèvre: The emergence of coronaviruses–and indeed other viruses–is something we should expect to happen. Given our footprint on Earth, COVID-19’s emergence is not surprising. What is surprising is how quickly it became a global issue. Preventing the spread and devastating economic consequences of pandemics can, to some extent, be managed by better and routine surveillance in emerging hotspots; and by incorporating disease risks as a factor in decision-making in transportation and trade networks.
Robinson: While the exact environment linkages to the current pandemic are still being investigated, we know that investing in a healthy environment, by halting habitat loss and degradation, can mitigate risk of zoonotic diseases. Improving biosafety and sanitary standards along the entire food value chain can also mitigate risks. We need to invest in a One Health approach that integrates the full human, animal and environment dimensions of preventing zoonotic diseases at international, national and local levels.
We know that the assessment will not be published until July, but is there anything you can reveal in advance?
Robinson: Zoonotic disease risk is associated with human activity on the planet—ranging from unsustainable agricultural intensification and increasing human demand for animal protein; to changes in food supply chains; to increased exploitation of wildlife; to more travel and transportation, and many others. We have to address these root causes. The report speaks to this.
The other main point we hope people will take from the report is that we cannot afford to retreat to what was “normal” before the crisis. We need to build back better: our policy responses must be evidence-based and nuanced to the realities associated with zoonotic disease emergence and the social, economic and cultural contexts of different countries. We need to raise more awareness on health and environment risks and prevention; expand our scientific inquiry into zoonotic diseases using multi-sectoral approaches linking human, animal and environment health; and enhance monitoring and regulation to mitigate specific risks. Operationalizing a One Health approach that breaks down siloes of human, animal and environment health offers our best way forward.
Want to find out more about zoonotic diseases? Click here to read key messages from the upcoming report.
