Save forests to stop pandemics, expert warns

Sickening: A third of new diseases are linked to land-use change like deforestation. © Nicole Strubing

Is conservation the long-term answer? As the coronavirus sweeps the world, science is highlighting the link between the rising numbers of new diseases and our treatment of the environment.

More than 300 million schoolchildren can’t go to school.

Italy has quarantined 16 million people.

Euro 2020 and the Tokyo Olympics might be cancelled. Airlines are folding.

Across the globe, Covid-19 is having an unprecedented impact.

But, with the focus on anxiety about infection, a growing number of scientists, this weekend, are warning that it is easy to overlook the fact that the origin and spread of viruses has a lot to do with the impact that we, as humans, have had – and continue to have – on our environment.

To start with, our interaction with the natural world, they say, is at the root of most illnesses: three-quarters of diseases begin in animals and cross over into humans.

This is true of Covid-19, which is believed to have started at a “wet market” in Wuhan, China. Such markets keep live animals on site to butcher for shoppers. Hygiene can slip in these conditions; viruses can leap to humans more easily.

There is a key additional factor, however. Wuhan is a city of more than 11 million people. Having found itself one human host, the virus could quickly infect others.

Urbanisation plays a massive role in the spread of disease – and not just because sickness moves fast in crowded places. The rapid growth of cities has wider environmental consequences, such as deforestation, which make outbreaks more likely.

Deforestation had occurred in the area of Guinea which saw the 2014 outbreak of Ebola. Bats carrying the virus were displaced and forced into closer contact with humans.

In regions of Africa where plague (a bacterial, rather than a viral, infection) is endemic, rats on farmland are twice as likely to carry the disease as those in conserved forest sites.

As humans destroy habitats, predators die out, leaving hosts free to proliferate. Overall, biodiversity falls but a high number of hosts survive. Animals carrying diseases are forced to search for food in human settlements.

For Suresh Kuchipudi, a virologist at Penn State University, these factors are massively increasing the risk of new illnesses reaching humans. “Constructive conservation strategies” are urgently needed to reduce deforestation and keep animals and humans apart.

Is he right?

Conserve to survive

From one point of view, yes, unquestionably. Pandemics have social – not biological – causes. Human-made pressure on the environment will increase in coming decades, with a huge explosion of cities. Climate crisis is adding to environmental damage caused by development. Without new approaches to conservation, we will find ourselves ever more at the mercy of global crises, such as Covid-19.

From another perspective, there are more urgent things to think about. Kuchipudi himself also stresses the need for a “global surveillance system” to track new viruses. The reason Covid-19 has spread across the world is because the early response was too slow when it first appeared in Wuhan. Getting better at identifying and stopping new diseases when they arise should be the priority.

You Decide

  1. Some think we need to reduce animal-human interaction. Would you mind never seeing an animal again if it meant no new diseases?
  2. Which is more important: conserving forests or expanding cities?


  1. You are running a campaign to convince people about the link between deforestation and the spread of diseases. In groups of four, research a two-minute presentation to explain the connections. Choose one of your group to present to the rest of the class.
  2. In pairs, research the links between deforestation, agriculture, and urbanisation. Write a one-page report to the government, outlining the risks posed by failing to conserve the natural environment.

Some People Say...

“An inefficient virus kills its host. A clever virus stays with it.”

James Lovelock, scientist, inventor, and environmentalist

What do you think?

Q & A

What do we know?
Humans have felled 46% percent of all the trees on Earth. Since 1950, the world’s urban population has grown from 751 million to 4.2 billion (in 2018). Recently, its growth has been especially rapid in Asia and Africa, which is also where most new diseases are appearing. The majority of these have originated in animals – the coronaviruses responsible for Sars in 2002, Mers in 2012, and now COVID-19 all started in bats, infected other animals, and then reached us.
What do we not know?
When new diseases will appear; what causes them to become a pandemic, and exactly why deforestation and urbanisation increase the chances of humans getting infected. There are many factors involved and many possible explanations. It is clear from the available evidence, however, that reducing deforestation and animal-human interactions would also reduce the risk of the transmission of new diseases to humans.

Word Watch

Ceasing to operate.
The name for the strain of coronavirus currently infecting people.
Different and more extreme than anything that has happened before.
A circumstance, fact, or influence that contributes to a result.
Humans (or animals) that carry a disease and allow it to be transmitted to others.
The growth of cities and the number of people living in cities.
A virus which has had a number of outbreaks in Africa since the 70s.
Relating to a disease regularly found in a certain place or among certain people.
The natural home of an animal.
Increase in number very quickly.
Scientist who studies viruses.


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