Did you know that around 60 per cent of all infectious diseases in humans are zoonotic, as are 75 per cent of all emerging infectious diseases, in other words they come to us via animals?

Zoonoses that emerged or re-emerged recently are Ebola, bird flu, Middle East respiratory syndrome (MERS), the Nipah virus, Rift Valley fever, sudden acute respiratory syndrome (SARS), West Nile virus, Zika virus disease, and, now, the coronavirus. They are all linked to human activity.

The Ebola outbreak in West Africa was the result of forest losses leading to closer contacts between wildlife and human settlements; the emergence of avian influenza was linked to intensive poultry farming; and the Nipah virus was linked to the intensification of pig farming and fruit production in Malaysia.  

Scientists and specialists working at the United Nations Environment Programme (UNEP) have been pulling together the latest scientific facts about the coronavirus—what we know about the virus and what we don’t know.

While the origin of the outbreak and its transmission pathway are yet to be discovered, here are six important points worth knowing:

1. The interaction of humans or livestock with wildlife exposes them to the risk of spillover of potential pathogens. For many zoonoses, livestock serve as an epidemiological bridge between wildlife and human infections.
2. The drivers of zoonotic disease emergence are changes in the environment—usually the result of human activities, ranging from land use change to changing climate; changes in animals or human hosts; and changes in pathogens, which always evolve to exploit new hosts. 
3. For example, bat-associated viruses emerged due to the loss of bat habitat from deforestation and agricultural expansion. Bats play important roles in ecosystems by being night pollinators and eating insects.
4. Ecosystem integrity underlines human health and development. Human-induced environmental changes modify wildlife population structure and reduce biodiversity, resulting in new environmental conditions that favour particular hosts, vectors, and/or pathogens.
5. Ecosystem integrity can help regulate diseases by supporting a diversity of species so that it is more difficult for one pathogen to spill over, amplify or dominate.
6. It is impossible to predict where the next outbreak will come from or when it will be. Growing evidence suggests that outbreaks or epidemic diseases may become more frequent as climate continues to change.  

“Never before have so many opportunities existed for pathogens to pass from wild and domestic animals to people, says UNEP Executive Director Inger Andersen. “Our continued erosion of wild spaces has brought us uncomfortably close to animals and plants that harbour diseases that can jump to humans.”

UNEP staff are continuing work in these important areas. Notes shared by its Science Division are available online with additional information, including a list of questions yet to be answered.  

Nature is in crisis, threatened by biodiversity and habitat loss, global heating and toxic pollution. Failure to act is failing humanity. Addressing the novel coronavirus (COVID-19) pandemic and protecting ourselves against future global threats requires sound management of hazardous medical and chemical waste; strong and global stewardship of nature and biodiversity; and a clear commitment to “building back better”, creating green jobs and facilitating the transition to carbon neutral economies. Humanity depends on action now for a resilient and sustainable future.

For more information, please contact: Maarten Kappelle at [email protected]