Animal-to-Human Disease Transmission Linked to Wildlife Stresses and Habitat Destruction
Camels and bats, rats, birds, pigs, ticks, mosquitos, fleas, armadillos and cattle: what do they all have in common? It might sound like the cast list of a macabre Tim Burton movie, but in real-life these animals and insects have played lead roles in a deadly series of outbreaks known as zoonotic diseases.
Zoonotic diseases are those transferred from animal to human, either by direct exposure to the animals or by the consumption of food made from these animals. Zoonotic diseases have been around for a long-time. Covid-19 is one of them.
Also included on the list of zoonotic diseases to have impacted on humankind are the 1918 Spanish influenza, reported to have wiped out over 50 million people worldwide; the 1957 Asian flu pandemic which killed 1-2 million; the 1968 flu pandemic which was responsible for 1-4 million deaths; bubonic plagues; forms of leprosy and most lethal of all, the Black Death (also known as The Plague) which wiped out 70-200 million people in the 14th century.
Most of those examples may sound of biblical heritage or at the very least in the rather ancient past. Worryingly though, a resurgence of zoonotic outbreaks sees modern medicine still struggling to keep up with the adaptability of our most unwelcome passengers.
Recent examples show these outbreaks are happening at an increasing rate, as we have seen with the outbreaks of Ebola, SARS and the even more obviously alarming current pandemic. A report published by the United Nation’s Food and Agriculture Organisation (FAO) said that over 70% of new diseases that have emerged in recent decades are of animal origin. The report, which was supported by the Government of Ireland (World Livestock 2013: Changing disease landscapes) indicated that human health is closely linked to livestock and animal health.
Described by the Centres for Disease Control as the world’s deadliest animal, the mosquito has topped the list of animals/ insects responsible for the highest number of human deaths for some time now. While the humble mosquito has been responsible for in the region of 750,000 human deaths annually, via zoonotic transfer and its spread of diseases such as malaria, dengue, West Nile Virus and yellow fever; over the past year at least, the mosquito’s zoonotic death toll was topped by the latest zoonosis, Covid-19, a killer that has left almost 2 million deaths in its wake so far.
Zoonotics aside, in recent years, second only to mosquitoes, the human species (with its uniquely-human homicidal tendencies) was the other animal most responsible for annual human deaths.
While there’s some debate about whether Covid has its origins in pangolin, bat or other wildlife populations in China, we could arguably say that human beings should be top of the above list.
Science concurs that the impacts of human-made climate change, biodiversity decline and habitat wipe-out are linked to the rise in zoonotic diseases. Humankind, it appears, is ultimately most responsible for the threats to its own survival.
These self-made problems can only be put right by a continued rise in resources, research, monitoring and action aimed at halting climate change, and biodiversity and habitat decline. With the rise in zoonotic diseases we are seeing, the timeline is urgent and further proof of why the Dáil’s declaration in 2019 of a climate emergency, was apt. It’s an ongoing emergency on many levels and it’s on our doorsteps.
Human activity has been responsible for nature loss as a result of the destruction of ecosystems (in particular deforestation which is responsible for 31% of zoonotic diseases) driven by unsustainable levels of consumption, with large-scale industrial farming being a factor, as well as the illegal wildlife trade.
Links to the destruction of nature is also borne out in more recent communications from the UN. In April 2020 the United Nations Environment Programme (UNEP) published two short videos explaining the links. In July 2020 they published a report along with the International Livestock Research Institute entitled Preventing the Next Pandemic – Zoonotic Diseases and how to Break the Chain of Transmission.
The UN reported that COVID-19 is just one example of the rising trend of diseases “caused by viruses that have jumped from animal hosts into the human population.”
The rising trend in zoonotic diseases, the report confirms, is driven by an increased demand for animal protein; a rise in intense and unsustainable farming and “by the degradation of our natural environment – through land degradation, wildlife exploitation, resource extraction, climate change, and other stresses.”
As the COVID-19 death toll continues to rise (despite the best efforts of governments and health services) and the pandemic disrupts economies across the world, the report warns that unless governments take active measures to prevent other zoonotic diseases from crossing into the human population, we can expect to see a steady stream of these diseases in the years ahead.
Healthy, biodiverse ecosystems are resilient, adaptable and help to regulate diseases. The changes in temperature and humidity caused by climate change facilitates the spread of diseases though.
Other factors also come into play, including: increased migration of animals driven from their habitats by climate change; closer contact between animals and humans; animal population reductions and other stresses resulting in plummeting genetic diversity, which facilitates virus spread. Links between zoonotic disease outbreaks and floods and droughts have already been scientifically established. The impacts of climate change is seeing the frequency of these events increasing.
Our continuing encroachment on ecosystems to satisfy our consumption demands have lead experts to warn that we are entering the “era of pandemics”. We cannot go ‘back to normal’ once Covid-19 is behind us. ‘Normal’ will only bring us more devastating pandemics.
A massive effort is required to protect our natural world. Covid-19 has reminded us of the devastating consequences of failing to do so. Initiatives are only as good as their levels of implementation, but there is room for hope around the many measures that can and must be taken, including the following:
We must change course, reassess our relationship with nature and rethink our food and trade systems, reducing the rampant consumption that drives deforestation and wildlife exploitation.
Greater conservation of protected areas is vital, as well as proactive engagement in nature restoration – reversing biodiversity loss and reshaping our agricultural practices with a move away from intensive industrial farming. Health systems should be strengthened, not just for humans but for animals and wildlife, with ramped up surveillance of infectious disease in wildlife and livestock.
The knowledge and the will is there to make these changes. Public concern and engagement has never been stronger. Later this year, the Convention of Biological Diversity will hold a global conference (COP15) in Kunming, China. It’s hoped that the Kunming conference will do for biodiversity loss, what the Paris Agreement did for climate change by agreeing binding, global targets. Agreeing to protect 30% of the planet’s land and oceans by 2030 would be a good start.
At EU level, this week in the European Parliament there will be a Public Hearing on ‘Facing the Sixth Mass Extinction and Increasing Risk of Pandemics’ examining the role of the EU Biodiversity Strategy for 2030. We’ll also be holding an exchange of views with the European Commission on the Environment Action Programme to 2030.
Work on a far-reaching piece of legislation is well under way on the legislative-review-stage of The 8th Environment Action Programme, of which I am Rapporteur (European Parliament’s lead-negotiator). Setting and putting in place -long-term goals, monitoring and measuring tools and the framework for increasingly committed worldwide targets is crucial, and The 8th Environment Action Programme is about all of these things and more.
Also at EU level, the European Commission is expected to come out with a legislative proposal on minimising the EU’s contribution to deforestation, as well as another legislative proposal on nature restoration. For Ireland, this will be particularly important as we urgently, for example, need to restore our degraded peatlands, with their massive carbon-capture potential.
The health of our society and economy depends on the health of our environment. The UN identify the ‘One Health’ approach, which unites public health, veterinary and environmental expertise, as the optimal method for preventing as well as responding to zoonotic disease outbreaks and pandemics.
When we fight to protect the health of our environment, we are implicitly fighting to save lives and to protect human health, the health of our society and the health of our economy.