Biodiversity is a natural repository for more than half of the medicines that we develop. A large number of disease outbreaks are zoonotic, primarily caused by ecological damage. By changing human behavior, we can make a big difference in terms of handling future pandemics, emphasizes Dr. Carlos Zambrana-Torrelio — Associated Vice-President for Conservation and Health at EcoHealth Alliance and a Research Associate at the Bolivian National Herbarium, in a discussion with Dr. Sean O’Brien — President & CEO at NatureServe
Ecological destruction and loss of habitats of many species causes a lot of problems. Is this also associated with the transmission of viruses from animals to humans?
Most of the diseases in humans come from animals — from domestic and from wildlife. These are called zoonosis, and there are around 435 diseases that jumped from animals over the past 60 years into humans. Over 60% of these “spillover events” are really related to some form of change —for example, deforestation or increases in agricultural activities. What happens is when these human activities occur, the contact with wildlife increases. So, we have more encounters with these animals and therefore we get more viruses coming from these animals to us.
Just to be clear, biodiversity itself doesn’t represent a threat to humanity — it’s that we humans are getting more comfortable with destroying the habitat of these animals and we are having more encounters with them.
Diseases like AIDS and Ebola also originated from animals. Do you think other than deforestation and rampant ecological destruction, poaching and smuggling of exotic wild animals also plays a role in the spread of these contagions?
HIV jumped from primates to humans. Ebola is linked to deforestation and jumped from bats to humans. In Latin America, we have several different examples of hemorrhagic fevers like hantavirus. Recently, in Bolivia we witnessed the Machupa virus that jumped from rodents into humans, leading to very high mortality rate.
But it’s not just that. There are also human activities and practices that cause diseases. In the case of COVID-19, there is strong evidence that it jumped from bats into humans in a wildlife market in Wuhan, China. What happens in these places is that we get wildlife from different regions in China and then people go and buy meat. There are several species of animals in the same place.
So, if you can imagine, we have bats, pangolins, sometimes dogs, cats, civets —all different species of domestic and wild animals mixed together. Since they don’t have necessarily good refrigeration systems, all animals are kept alive there until the moment they are sold to humans. So, when they are sold, there’s the moment when the people kill the animal and all the blood gets mixed into other animals, and then there is the opportunity for spillover of viruses. That’s what we believe has happened this time. There are two hypotheses that have been discussed: one is jumping from a bat directly to a human, and then the other idea is that it jumped from a bat to a pangolin, which changed the virus a little bit, and then it jumped to a human.
As per estimates by the World Economic Forum (WEF), over 50% of modern drugs are developed from natural plant extracts. So, clearly, biodiversity is essential not only for the ecosphere, but also for human health and medicine. What do you think needs to be done to preserve biodiversity in a holistic manner and enhance its role in developing new vaccines?
Several treatments for health come from plants. Recently, it has been discussed that chloroquine medicine that has been used for years to treat malaria, can be used in combination with other medication to cure or to treat COVID-19. But this quinine comes from a plant from the Amazon, so it’s important to keep all this biodiversity, but also work to explore all the active principles that are in these plants and can potentially be used for human health.
What do you think should be done for the realization to hit home that preserving biodiversity is intrinsically connected with human health?
We talk all the time about the risk of emerging infectious diseases and it’s important to clarify that there are three components of risk. One is what we call hazard — in this case, it’s biodiversity, but especially mammal biodiversity, because these mammals are hosts for all these different pathogens. By itself, biodiversity doesn’t represent a risk to humans — it’s when we disturb the biodiversity that we get into trouble.
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The second component is the exposure. Exposure is extremely important, and it’s related to human behavior. We are already in trouble because of human behavior and our ideas. For Instance, there is a widespread belief in China that traditional medicines and particular types of meat make people healthy; it’s putting us in danger. But China is not the only place; this happens all around the world — bushmeat consumption happens in Africa, Latin America; it happens everywhere. By changing human behavior, we will make a big difference in how we handle future pandemics.
Finally, there’s a third component, which is vulnerability. We can understand it as vaccination. That’s why we have been telling people that in this case, people older than 60 years of age are more at risk because they are more vulnerable to this disease. But in other cases, like Zika virus, we also said children that are young, like 5 years or younger, are at risk as well because they are developing the immune system. So, vaccination is important not just for COVID-19 but also for the regular influenza that happens every year.