Avoiding COVID 2.0

What’s the greatest step you can take to reduce the emergence of infectious diseases?

I was lucky enough to get my first COVID-19 vaccine last Friday and was quite unprepared by how emotional it would be. When we first arrived at the vaccination site, I was filled with gratitude for the small army of volunteers who made sure the process went smoothly and safely. When the angelic RN administered my shot, I became quite teary eyed. But that wasn’t the end of the big emotions, as we drove home I was in awe that I’d been vaccinated in little over a year after COVID reached our shores - well done scientists. As the weekend progressed, I started to realize the end of my seclusion is drawing near and I became full of excitement at the prospect of going to dinner at a friend’s, or even a restaurant. And that’s just the last 3 days! It’s

been a hell of roller coaster ride this year. But the time to wallow in joy is not yet upon us. We’ve lost almost 3 million people, millions more have been struck with long term COVID impacts, and most people on the planet haven’t yet been able to access a vaccine. And, of course, epidemiologists warm we are likely to face more epidemics in the coming years.

The Global Risks Report ranks threats to humanity, considering environmental crises, cyber crimes, terrorism, financial crises, mental health epidemics and anything else likely to have global scale negative impacts on human society. For the first time ever, infectious diseases ranked number one in terms of impact, and fourth in terms of likelihood of occurrence. The impact of new infectious disease was considered as society’s most damaging potential event, but was considered less likely to happen than climate action failure, human environmental damage and extreme weather. Strangely enough, the causes of epidemics, climate change, and ecological damage are not different. If you’ve read my previous newsletters, you’ll know that our consumption is the primary driver of all of these risks.

As I’ve summarized in my book, food, transport, and running our homes drive around 80% of the destruction of many of our natural resources. And, as it turns out, each of these contributes to the rise in emergent infectious diseases. The transport link is straightforward enough. As our travel appetite has increased, from 310 million flights in 1960 to 4.4 billion in 2019, the vectors for disease transmission have of course gone up hand in hand. Indeed, we are said to be within 36 hours of everywhere else on the globe, which is how COVID-19 became a global epidemic within a few months of the first identified case. Next, running our homes requires all kinds of natural resources like fresh water, soil, wood, metals, and fossil fuels to produce our electronics, furniture and fabrics, and so forth. Thus the average American or British home contributes dramatically to the destruction of natural ecosystems. But it is in our consumption of food that we make the greatest impact on the natural world and, thereby create the most opportunities for infectious diseases to erupt in the human population.

Food production is responsible for at least 80% of deforestation and research has shown the biggest driver for emergent infectious disease is land use change - i.e. destroying natural ecosystems and replacing them with pasture, cropland or cities. In fact, land use change is not just a slightly larger driver than other pathways for emergent diseases, rather land use change has been the primary driver for 30% of emergent diseases between 1940 and 2004. This is twice as large as the next biggest driver, which is agricultural industry changes, again a food driver. The third largest driver of emergent infectious disease is travel and commerce. Together, travel, land use and agriculture changes, have driven 60% of the emergent diseases in the past 64 years, while also accounting for two of the three drivers responsible for 80% of natural resource loss. There’s something drastically unhealthy with this state of affairs.

A new infectious disease emerges in people every four months and 75% of these are zoonotic, or pass from animals to humans. If diseases jumping from animals to humans sounds exotic to you, you’ll quickly realize that you’re probably quite familiar with the concept when you consider the following. Mosquitos kill more people than any other animal, including (thus far) other humans. This is because mosquitos are a vector for the zoonotic diseases of malaria, yellow fever, dengue fever and encephalitis. Bats carry rabies and viruses related to SARS, and are quite possibly the source for COVID-19, MERS, Ebola and Nipah. HIV is thought to have come from monkeys. These zoonotic diseases don’t only come from wild animals, many come domesticated animals. Avian flu is known to have been fostered by industrial farming of chickens and the global movement of both people and animals. In the case of SARS, it is suspected that wild animals serve as a reservoir of the disease and a domestic animal is a link host to humans. Less headline grabbing but continuously present and vastly damaging are other zoonotic diseases which are spread by domesticated animals such anthrax, bovine tuberculosis, rabies, pig tape worm, Japanese encephalitis, and sleeping sickness.

Worryingly, the rate at which zoonotic diseases arise in humans has been rising in the past 3 decades. Given the links to habitat destruction this probably won’t be a surprise to many of us. A UN report, Preventing the Next Pandemic, lists 7 reasons emergent infectious diseases are increasing

• Increased demand for meat,

• Unsustainable agricultural intensification - responsible for a full 25% of all emergent infectious diseases,

• Increased use of wild animals - bush meat, medicine, wildlife trade etc,

• Resource use and land use change - creating novel and diverse contact between wildlife, livestock and people,

• Increased travel - we are now a global community,

• More complex food chains - lengthening supply chains and creating more opportunities for cross contamination; industrial meat packaging plants and wildlife markets both are hot spots for transmission and pathogen growth, and

• Climate change - tropical diseases such as malaria are becoming more wide spread.

The report concludes that the best hope is “The One Health” approach, that we manage human, environmental and animal health together. Hmm, seems we are all connected after all.

So, dear readers, if land use change is the number driver of emergent diseases, what can we do to lessen the chance of another pandemic? Anyone? Come on, pipe up. Oh yes, dear little-know-it-all-Pru-at-the-back-of-the-room, you are right. To reduce our risk of infectious diseases we can “reduce our meat consumption”. The vast majority of land use change is due to the conversion of natural lands to pasture or crop land to feed livestock. If we do chose to eat meat, we can still contribute to reducing emergent diseases by purchasing locally raised creatures who have had the freedom to roam and not been locked into disease hothouses. The impact of local, free range, organic meats is huge - avoided deforestation (reduced pathogen exposure), shorter supply chains (less chance of pathogen transmissions) and healthier animals (less transmission again). Who knew we’d end up back here when we started talking about infectious diseases?