At times like this, I am glad for my ears, else I would not be able to wear a face mask. Masks are now a mandatory requirement on public transport and in many establishments here in France. However, as someone with an acute sense of smell, wearing face masks is not a little dispiriting.
I am now less likely to be enticed down little alleys following the scent of a fragrant boulangerie or to appreciate the perfumes on elegant women. On the plus side, people with halitosis are less of a problem. While we struggle to get past this Covid-19 pandemic, perhaps we can accept the current travails as a trial run for the next pandemic. Because there will very likely be another pandemic, perhaps not in our current lifetimes, but the probability is almost a certainty. Let me explain why.
Zoonoses are diseases that are transmissible from animals to humans, such as Covid-19. However, humans can also transmit diseases to animals and these are called zooanthroponoses. The main problem with zooanthroponoses is that these diseases can return and re-infect humans, perhaps in a modified state.
For example, Staphylococcus aureus was transmitted to animals at livestock farms and have returned to infect humans as Oxacillin-resistant Staphylococcus aureus (ORSA). Basically, a zooanthroponose can acquire resistance to antimicrobials due to constant exposure to animal feed containing such compounds before the disease returns to humans as a harder-to-cure or even untreatable malady.
Zooanthroponoses have been a problem for some time, though the incidence levels are usually low enough at present not to cause widespread alarm. The most well-known examples are probably Mycobacterium tuberculosis and methicillin-resistant Staphylococcus aureus (MRSA) and I know the latter well because it was what killed my father.
But at least zooanthroponoses are generally known to scientists and the medical profession. There is a much wider problem with zoonoses which are not known to researchers at the moment, but which are likely to have a significant effect on human populations, perhaps even worse than Covid-19.
Let us review first the impact of currently known zoonoses. An earlier 2012 study estimated 56 zoonoses were responsible for around 2.5 billion cases of human illnesses and 2.7 million human deaths every year. The top 13 zoonoses were responsible for 2.4 billion cases of human illnesses and 2.2 million deaths annually; all 13 were related to livestock and/or associated with wildlife. The most deadly were gastrointestinal diseases caused by zoonotic bacteria – curiously most of the 43 newly-detected zoonoses between 2004 and 2012 were viruses, not bacteria.
Compounding the problem is the development of antimicrobial resistance (AMR) in many zoonotic pathogens. In 2019, the World Health Organisation (WHO) estimated at least 700,000 humans die each year from AMR – this figure is projected to rise above 10 million deaths annually by 2050. If you are curious, there is an earlier article, ‘What’s Bugging Meat?’ which reviews a measure called P50 used to measure AMR.
As a comparison, the current estimate is that Covid-19 will cause the deaths of over one million people by the end of this year, although the actual final number will be a function of how seriously countries and people around the world enforce measures such wearing face masks, social distancing and hygiene. At present, some countries have a bizarrely casual attitude to health safety which means that a second wave of Covid-19 will be pretty much a certainty for them in the coming weeks and months. It is basic maths.
So if you believe the statistics from the WHO, one might suggest the world is already having a slow-burning but growing pandemic called AMR which is currently killing much more than half a million people a year, and Covid-19 is just another disease adding another million or so to the death toll this year.
The huge difference is that mitigation against Covid-19 is possibly easier than protection against AMR. Also the expectation is that deaths from Covid-19 will decline either due to the availability of a vaccine (somewhat unlikely) or better therapeutic medications (more likely). However, deaths from AMR are not forecast to decline for the next 30 years, mainly because the nature of AMR precludes any treatment options.Our food supply – why does it matter so much?To say our planet and food production systems have been badly managed for some time is probably too euphemistic. The impact humans have on the planet, usually to do with industrialisation and commercial food production have created the following impairments to our environment:
> Climate change
> Land cover change
> Land degradation
> Loss of wetlands and other habitats
> Loss of biodiversity
> Depletion and contamination of freshwater resources
> Effects of urbanisation
> Damage to coastal reefs, ecosystems and widespread pollution of oceans
The impacts on humans are widespread and varied, and some examples are:
> Air pollution
> Chemical pollution
> Population displacement
> Regional conflicts
> Alteration of the profiles of infectious diseases
The last point is what we will focus on today.
It is widely believed that an early variant of the coronavirus that eventually became SARS-CoV-2 originated in bats, and this pathogen may have had its virulence “enhanced” by transitioning through another animal host before it reached humans. Until we can identify Patient Zero, we can never be sure – and there seems to be little chance of finding him or her now.
The main point is that human activities which cause the destruction of the environment and natural habitats also increases the chances of brand new pathogens evolving – and humans have no innate immunity against such novel pathogens.
Our food supply is one example of human activity which is destroying our environment, causing global warming, huge losses of biodiversity while at the same time wiping out vast swathes of wildlife habitats which will never be able to return to normal.
A species can only be extinct once, and at least 200 to 2,000 species a year become extinct. The remaining species are adapting to humans in ways which may be uncomfortable and also somewhat complicated. It is not just the species that we can see that are adapting – it is the unseen viruses and bacterium in other species that are hopping over to using humans as hosts.
Intensification of livestock farming and meat production are mixing animals, drugs and wildlife together in chaotic ways even as humans operate meat production in the most expedient and economically profitable manner. Not only that, such animals are kept in crowded and extremely stressful environments which lower their immune systems hence turning them into walking disease laboratories constantly evolving strategies against antimicrobials and animal immune systems. Reduced natural environments increase contact between animals and humans; this offer an ideal platform for diseases to evolve and refine themselves.
It is not a huge leap for an animal pathogen to adapt and jump to humans, in what is termed a “zoonotic transfer” and such transfers may involve more than one species along the way as the pathogens pick up new strategies from pathogens in other animals before infecting humans.
Even though we cannot see them, pathogens are mutating every day and we only get to know those that survive. And there are not a few of them. There have been at least 200 infectious diseases which have caused more than 12,000 outbreaks in human populations over the last 30 years. On average, a new kind of zoonotic transfer happens every four months.
Such high incidences of zoonotic transfers means that it is only a matter of time before another major pandemic hits our planet. Believe it or not, we have been lucky with Covid-19 because the mortality rate is lower than it could have been, and it could also have been more infectious.
Our luck may soon be affected by the melting permafrost (due to global warming) which is causing the release of countless thousands of viruses currently frozen in the ground in Artic areas. The impact of these ancient, prehistoric viruses on humans is currently unknown, but scientists have been able to revive and activate viruses such as Pithovirus sibericum which had been locked in the Siberian permafrost for over 30,000 years.
If one is interested in reducing the probability of a new zoonotic pandemic, then the best option would be for everyone to cut the consumption of meat. The production or sourcing of meat is one of the major causes of global warming, land/water pollution and destruction of the environment. Additionally, 16 out of the 21 major zoonoses in the UK are related to meat production and/or consumption. Note that SARS-CoV-2 is very probably another zoonose linked to wildlife meat.
Put another way, there has never been any zoonotic transfer between vegetables and humans, so eating vegetables is safer in terms of zoonoses.
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