A zoonosis is any disease that's naturally transmissible between people and animals and
it could be bacterial, it could be viral, it could be parasitic or could be through other infectious agents.
The majority of emerging infectious diseases are in fact from of the zoonotic origin.
Around 60% of the of such diseases are known to have been transmitted from animals and only in
very exceptional circumstances do we have the right combination that means that we are facing
something of global impact such as the current COVID19 epidemic.
Diseases can move from animals into
humans in numerous and sometimes complex ways including direct contact with livestock or with
captive wild animals or with pets, both exotic and and domestic pets. And this can both be the direct
contact with the animals themselves or perhaps contact with some of their
secretions including saliva, blood, urine or fecal matter.
But the pandemic potential of a zoonotic
disease is strictly linked to the ability of that disease to pass between people. And so it needs to
involve both contact and a specific disease that's able to transmit directly between people.
So how did COVID-19 pass between animals and humans? There's a lot of debate in this area, there's a
lot that we don't know and might never know but there's evidence that coronaviruses that infect
people originated in bats and rodents. We know that coronaviruses can have intermediates in pigs
cattles, palm civets, dromedary camels and other species and there's a lot of uncertainty about the
exact path that COVID-19 took to reach people. The virus with the closest match has been found in
several Horseshoe bat species and this indicates that this could have been an ancestral origin of
the virus but even the closest relative of these doesn't have a strong capability to infect people.
We know that situations that involve close contact between multiple wild species, domestic species and
people may allow for recombination. Combination of different viruses more distantly related viruses
to create a new type. And this could have pandemic potential.
For our work we looked at all categories
of animals so both livestock but also animals which are wild but farmed. So for instance
civets or bamboo rats but also we looked at pets both exotic and domestic pets and therefore
we included all categories of animals. And we believe that this is very important going forward.
So who is at the root of the cause of disease emergence is it people or is it animals?
Unfortunately it's definitely people and that's because how our societies interact with wildlife
wild spaces directly or indirectly is driving changes and this is increasing
pandemic risk. Every day we're coming into closer and more intense contact with wild
animals in world spaces, converted spaces and domestic animals in farmed and other settings.
It's a lottery but every single day we're buying more and more tickets.
We will never be able to completely prevent the transmission of diseases from animals into humans. It has
gone on since we humans first appeared and it's likely to to continue. For spillover to occur and
for a pathogen to move into human populations and be able to transmit between people there's a
huge number of barriers and the more that we learn about these barriers the better we might be able
to use them to our advantage. And this will involve changing human society, how we behave in particular
interfaces with wildlife and domesticated and farmed animals.
We need to seriously consider investing and supporting food production systems especially in the developing world that are
responsible and that are adequate in relation to to hygienic and safe food production because
ultimately as this pandemic shows health problems can can become global rather than being restricted
at the national level. In addition to that we should also look and identify alternatives for
for products whether that would be meat or skin or traditional medicine or any other animal products
that are currently high risk but which could be substituted with less risky alternatives whether
that's synthetic or plant-based alternatives. All of this has the potential to to reduce
the risks that that we are facing in relation to a potential new pandemic of animal origin.