Copyright Darius A. Irani,2023
Most pathogens are designed to be killing machines and have been around for thousands of years. So, it is interesting to study if their frequency and behavior changed as our population changed. However, understanding their impact on human society had to wait until men started keeping a record of these events and how they had shaped their lives. The earliest such record is during the siege of Jerusalem in 701 BCE. In the intervening 2,700 years there have been close to 100 recorded events of epidemics and pandemics.
In the early years knowledge of medicine was almost nonexistent. Trying to diagnose what a pathogen might have been based on the descriptions provided by laymen almost three millennia ago is challenging. Thankfully, there are many modern scientists who have devoted much effort to analyzing the documented symptoms and providing a best guess as to the nature of these killers. Equally important is a parallel body of research that provides us with estimates of changes in the world’s population during this period. So, finding such a correlation, if there is one, is possible.
However, as one digs into the available data, one realizes that we are dealing with something much more complicated. Not only is there a correlation between the frequency of the pathogens and the growth of the human population, but we also see four other traits: some pathogens exhibit a singularity of purpose; some an ability to go dormant, when necessary; some have a subsequent influence on the course of history far out of proportion to the impact of the pandemics themselves; and, some display an ability to adapt to our defenses and to evolve into lethal variations. When looked at holistically we are tempted to question the very nature of Nature. Is Nature just a benign aggregate of all living things around us? In which case these events are random and accidental. Or, is Nature far more complex? Potentially even sentient. If so, with what ultimate purpose?
(At the end of this essay is an Xcel spreadsheet. It contains a list of all the known pandemics/epidemics, their date and possible nature of the pathogen.)
CORRELATION or COINCIDENCE
Our population increase has not been a gradual linear process. Instead, it has been periods of exponential growth. Our span of 2,700 (701 BCE to modern times) years can logically be broken into three eras for deeper analysis.
E1: 701 BCE to 1499 CE (2,200 years) The world’s population grew from 75 million to 450 million. A very modest average of less than 200,000 per year. There are only 11 recorded events. Three were smallpox, five were the plague (Yersinia pestis), and three are not fully understood. This averages out to one event every 200 years. During this span, our knowledge of medicine was limited. We did not know what was causing these illnesses or how to stop them, so they were able to run rampant until they petered out on their own. The most devastating pandemic ever recorded occurred in this era. The Black Death of 1347 – 1351. It is estimated that as many as 150 million died during this single event.
E2: 1500 CE to 1899 CE (400 years) We transition from the Middle Ages to modern times. There was an explosion in both the world’s population and in international exploration. The population tripled to 1.6 billion. This is an average increase of four million every year. The number of pandemics also tripled to 37. We are now looking at a major event about every eleven years, or twenty times more frequently than in E1. The bacterias dominate for the last time with 26 events. The nature of the bacterium changed abruptly in 1816 when the old reliable plague had run its course and was replaced with cholera (more on this later). Smallpox starts to emerge as an efficient killer worldwide. Many sources suggest that in 18th century Europe it killed about 400,000 every year, and 500 million in the century preceding its extinction in 1980. Its spread worldwide can be directly linked to human exploration and colonization. Indigenous peoples in America and Australia had no resistance to it and were decimated, allowing for easy conquest.
E3: 1900 CE to 2020 CE (120 years) The human population now increases 5-fold to 7.8 billion. This is an astounding rate of 65 million per year, or 185,000 more births than deaths every day. The attacks keep pace with 44 events, about once every two and a half years, or four times as frequently as in E2. The numbers do not lie, bad things are happening more frequently, and in direct correlation with our population increase.
This was an egregious and selfish increase. No other species could sustain such an expansion. There is simply not enough space or naturally occurring food on the planet. Humans, however, have been endowed with some unique skills. We are the only species that can grow our own food and mold our environment to suit our needs. We can expand into areas we were not adapted for by building shelters and controlling their environments to keep us comfortable. This, together with advances in medicine and agriculture, has enabled us to not only sustain this population growth, but to continue to increase it.
This population explosion is even more astounding when one considers the travesty that was the 20th century. It was a time full of anguish and despair. A total of 51 wars and 50 genocides would take 250 million lives. Pathogens would kill at least another 86 million. Many millions would be forced out of their ancestral homes and become permanent refugees in squalid camps. Yet, our need to procreate is apparently so primal that despite the uncertainty and even depravation of the basics of everyday life - or maybe because of it – we accelerated headlong down the path of geocide and self-destruction.
Such an expansion is not without a price. As the need for arable land increased, we started burning down our forests and woodlands. The other species that called these spaces their home were pushed out and started dying off. And, when the land was not enough to sustain us, we started denuding the oceans and polluting them. This is madness. We live in a spaceship. Everything we need to survive must come from within the ship. Just because we can grow our own food does not mean we can also provide the other prerequisites for life. For example, we cannot produce more Oxygen. There is ONLY ONE way in which our planet’s Oxygen is replenished. That is through photosynthesis in trees and through organisms in our oceans. Between deforestation, our population explosion and our dependency on combustion for providing energy, we are already seeing a steady decline in the level of atmospheric Oxygen. The end will not come for many generations, but when it does it will not be pleasant.
WHY ONLY US – A JUSTIFIED PARANOIA
As organisms go, viruses are very primitive. They do not even meet the accepted criteria to be called living. On their own they are ineffective and die after a brief lifespan. However, lodge them in a host and there is no stopping them. They will take over the resources of the host and multiply until they kill the host itself. Smallpox, Polio, and Measels are three of the most prominent of the historic viral killers. They also have something in common. They are all non-zoonotic. They have NO OTHER hosts in nature. Even our nearest relatives - chimps - cannot host them.
Cholera is a bacterium. It does not need a host to survive. It is alive in its own right. Starting in the latter half of the 19th century, it replaced the plague as the dominant bacterial killer. It too very rarely affects any species other than humans. There is no known insect vector for it, and no animal reservoir has been found.
There you have it. Four of the most prolific killers of all time have only ONE purpose. To maim and kill humans!
At some level this either makes no sense or poses a profound question. There was no evolutionary advantage for these viruses to restrict themselves to just one host – especially a host that lives in well-defined spaces. In fact, it is a death sentence. We discovered vaccines for all three viral killers, isolated humans who were infected, surrounded them with a ring of vaccinated humans and strangled the viruses into extinction. This would have been impossible if they had been zoonotic.
Smallpox has been around for thousands of years. It has killed millions of our species by making billions of copies of itself in its hosts. All this multiplication, and not a single mutation!! Compare it to Covid-19. In just three years we have seen over a dozen mutations, and they keep on coming. Modern estimates are that humans and chimps (and bonobos) have 98.7% of their DNA in common. All it would have needed was a small, fortuitous change, a minor alteration and smallpox could have jumped to a primate and still be around. But no. Whatever created it gave it strict instructions. You can ONLY kill humans. You cannot infect or harm ANY OTHER living creature. What then created such a killer, and why? If we can ever answer this question, we may have taken the first step in understanding what we are and why we are here.
AN INCOGNITO JOURNEY
Smallpox is an old-world disease. The early Spanish explorers brought it to the new world. In 1520, barely 20 years after Columbus landed on Hispaniola the first recorded pandemic would kill about 8 million in Mexico. Its journey across the Atlantic poses a conundrum. In those days, Spanish ships would leave the mainland and stop at the Canary Islands to replenish before starting the crossing. From there it would take about 35 days before landfall in the West Indies. Because it is non-zoonotic, the carrier had to be a crew member. It usually took 10 days after infection for the first symptoms to emerge. Even if he had been infected on the last day before leaving the islands, barely a third of the journey would have been completed before he showed symptoms and became infectious himself. In the cramped quarters of the ships of that time, the disease would have ravaged the crew. Yet, they appear to have arrived safely and mingled with the local population before the disease started its killing. This raises alarming possibilities. Can Smallpox can go dormant? Current thinking is that there are five viruses that can go dormant, but Smallpox is not one of them. If it did not go dormant then how did it cross the Atlantic? Might it actually be Zoonotic and we just don't know what the host is? Neither of these possibilities bode well for our species.
This could also be a warning to us that we are just one big, connected tribe – even more so now. There is nowhere we can go that is beyond nature’s reach. It did not need an intercontinental jet that could cross the Atlantic in eight hours. Just a small wooden boat propelled only by wind and sail was more than enough.
DECIDING BATTLES AND CHANGING HISTORY
Our perpetual belligerence and resulting wars - which are also well documented – have often played into the hands of these killers. Battlefields are a fertile breeding ground for pathogens. The weary survivors are easy prey for these microscopic predators, becoming unsuspecting carriers for spreading the diseases on their trek back to their homelands. In many cases, these pathogens have altered the course of a struggle with unforeseen consequences for years to come.
The earliest known record is during the siege of Jerusalem in 701 BCE by King Sennacherib of Assyria. It is referenced three times in the Bible (II Kings 18 & 19; Chronicles 32; and the Book of Isaiah 36 & 37.) “For I will defend this city to save it for mine own sake, and for my servant David’s sake. Then the angel of the Lord went forth, and smote in the camp of the Assyrians ….” (Isaiah) The implication is that God saved his people by infecting the Assyrians with some fatal disease. A more likely explanation is that the water wells outside the city walls had been deliberately poisoned. Whatever the cause, the Assyrians had bigger fish to fry and decided to move on from this place of death and pestilence. Thus, sparing Jerusalem and its fledging new religion, Judaism.
Sennacherib had no idea that this decision to spare Jerusalem would be one of the most important turning points in history. Had the Assyrians prevailed, “...Judaism would have disappeared from the face of the earth and the two daughter religions of Christianity and Islam could not possibly have come into existence. In short, our world would be profoundly different in ways we cannot really imagine.” (Infectious Alternatives by William H. McNeill)
The very next recorded epidemic is the Athenian plague of 430 BCE. It struck in the second year of the Peloponnesian war, when Athens was under siege and seriously overpopulated with refugees. The pathogen would decimate about a quarter of the city's population - about 75,000 - and was a significant contributor to its eventual defeat.
Early in 165 CE the Romans launched a military operation against Parthia. The returning troops brought Smallpox back with them. What followed was the first recorded pandemic. The effect on Rome was so devastating that it is thought to have created the conditions for the decline and ultimate fall of the Roman Empire. The ultimate killer was the plague/Black Death (Yersinia pestis). It coincided with the start of the 100-year war between England and France. Between them they had allies from 12 other European regions. Given the extensive breeding grounds, multiple carriers, and long journeys home, it would be the greatest killing event in all recorded history. Estimates of the number of dead vary from 75 million to 200 million.
ADAPTING TO OUR DEFENSES
Until the early 19th century, the dominant bacterium continued to be Y. pestis. Although the root cause of the plague would not be discovered until 1894, Europeans had realized as early as the “Great Northern Plague” of 1700 that separation of the sick from the healthy was the only way to contain this killer. Infected locations would be sealed off by ‘cordons sanitaires’ and the infected would be quarantined in plague houses. By the time of “Caragea’s plague” in 1813, Y. pestis’ ability to spread and kill was being severely curtailed.
Nature responded by coming up with a new killer. Gone now were the clearly recognizable buboes. Rats and fleas were no longer relevant. Nature started using water - the most essential of our nutrients to kill us. During the 19th century, cholera would break out in the form of six pandemics. It was so contagious that outbreaks that started in India would within a year spread throughout Europe and Asia. The timing of these outbreaks is enigmatic. Cholera is borne out of poor sanitation resulting in unsafe water and food. It would seem more likely that the Middle Ages, with their significantly poorer living conditions, would have provided a better breeding ground for such a pathogen. Yet it is conspicuously absent until the 19th century. It is almost as if Nature was hiding Cholera up its sleeve, waiting for Y. Pestis to run its course before unleashing it!
There are only two strains of cholera. The “classical” variant, and the modern version called El Tor. Both have existed in the waters of the Bay of Bengal for thousands of years. Yet, as we have seen, the classical version only became active late in the 19th century. Once it started, it remained unchanged, and spent the next 150 years emerging from the Ganges Delta at will to kill humans. Eventually, the advent of antibiotics would limit its mortality, though it still emerges in poor or war-torn countries where for obvious reasons sanitation has broken down. Late into the 19th century scientists began to recognize the efficacy of antibacterial chemicals and in 1928, with the discovery of penicillin the bacterial killers start to fade away. Eventually even smallpox was eradicated. Our planet was now facing a double threat: the human population was growing out of control and the ancestral killers that had served nature for centuries were now ineffective. So nature has now turned to a new class of pathogens – the Zoonotic viruses.
THE ZOONOTIC AGE
Because they are zoonotic, they cannot be eradicated. We cannot kill every host living in the wild. It is neither possible nor practical. Being viruses, we have no broad-spectrum antidotes like antibiotics. Each one needs a specific vaccine to control it. Within their hosts, they are free to mutate. Even a small mutation could render an existing vaccine useless. Our only remedy is to stay on top of the mutations and limit their damage. Then there are the anti-vaxers...
Humans started the 20th century with a catastrophe called WWI. Not to be outdone, Nature had its own calamity in store for us - the flu pandemic of 1918. It is thought to have started at Camp Funston in Kansas – the location of the first registered case – and then spread to Europe as thousands of US soldiers were deployed to the war zone. Initially it looked just like a virulent strain of the seasonal flu. By the spring of 1918 over half of the British and French troops living in the squalid cramped trenches of the Western front were infected, but not killed. By August 1918 it looked as though it had run its course. Sadly, this was not so. Somewhere in Europe it evolved into something so lethal that it could kill perfectly fit young humans within 24 hours of being infected. Before it finally petered out it had infected about a quarter of the world's population and killed as many as 50 million.
We will see this trio of dangers repeated in all the zoonotics: they are impossible to eradicate; once infected they can rarely be treated with any medication; and, to stay alive, they will evolve faster than we can keep up. Influenza type A variant H1N1 which was responsible for the outbreak in 1918 continued to evolve and circulate for the next 100 years. H2N2 emerged as the Asian flu in 1957-58, H3N2 as the Hong Kong flu in 1968-70 etc. Then, suddenly in 2009 it evolved into something quite different. Existing flu vaccines were ineffective in treating this new variant, and the result was a pandemic that may have killed as many as 500,000 worldwide.
In 1976 a new virus emerged from Africa – Ebola. It had remained hidden in the back waters of the Ebola River for 10,000 years. Its natural reservoir is suspected to be fruit bats which do not appear to be affected by it. Like smallpox and cholera, it almost exclusively targets primates, so it was primed to jump to humans. As our population mushroomed, our need for arable land and protein also increased. We went on a binge of deforestation and consumption of wild meat. This took us deeper into places we were probably not meant to go to. Someone ate an infected monkey, and Ebola jumped to humans.
It is a hemorrhaging disease. The Zaire variety has a mortality rate of over 80%, and death is a very bloody affair. The only reason it is contained is that transmission is not easy. It can only be spread by close and direct contact with an infected person’s bodily fluids. If it was any more contagious it would be the perfect killing machine.
AIDS emerged in 1981 and is still lurking. Its transmission is about as difficult as that of Ebola. Yet, Ebola has remained confined mostly to the African continent and the total number of deaths attributed to it are about 15 thousand, whereas AIDS has spread worldwide and is responsible for over 32 million deaths. Hmm.
This brings us face to face with THE zoonotic of our time – COVID 19. Like the other killers, the family of Corona viruses has been around for thousands of years. They all start out feeling like the common cold, but at least three variants are fatal to humans. The first is SARS CoV-1. It emerged from China in 2002. Its weakness was that it was not contagious during the incubation period, only after symptoms emerged. Thus, it was easy to identify and isolate the infected and prevent its spread. It only killed about 800 and was thousands of miles away, so we ignored it. Next came MERS-CoV in 2012. It jumped to humans from camels. It had a worrisome mortality rate of 35%. Because of the limited interaction between humans and camels, it could not get a large base of victims and petered out.
COVID-19 is the name of the disease that is caused by the SARS CoV-2 virus. It evolved from a pathogen that infected just a few thousand in 2002 (SARS CoV-1) to a pandemic that by 2022 had infected over 51 million worldwide and killed over one million. It is still around, evolving at a steady pace. It is zoonotic, so eliminating it is impossible, and every single host, both human and nonhuman, is a factory where random mutations are constantly occurring. We cannot control them or their effect on us.
There is no fairy tale happy conclusion here. The evolutionary trend does not end in some kind of peaceful coexistence between host and killer. The viruses want to live just as much as we do. They will constantly strive towards greater virulence. This ensures the largest number of hosts, which in turn provides the greatest number of factories churning out copies and mutations. We cannot afford an isolationist attitude. In the current age of jet travel, we are just one big, connected tribe. A virus that killed 800 Asians half a world away evolved into something that killed over 230,000 of our friends and families, on our doorsteps, just a few years later. If we had not ignored it in 2002 then we could have been ahead of the game with a vaccine when it got to our doorstep. The enemy is relentless and has an evolving arsenal that we can barely begin to comprehend. Denial and complacency will play right into its hands.
THE CONUNDRUM THAT WONT GO AWAY
Fast forward to September 2024. After 25 years, Polio has emerged in the war torn Gaza Strip. What has it been doing for all this time? It is a virus, so it must have a host to survive. It is non Zoonotic so the host can only be one of us. This leaves us with three alternatives:
Somewhere in Gaza - about the most densly populated place on Earth - an unfortunate family has for two and a half decades sheltered members who were infected with Polio. Within this family the virus has stayed alive with no one finding out about it, and no medical help being given to the victims. Hmmm!
The virus has somehow gone dormant waiting for just the right opportunity to wake up. What does it even mean for a virus to go dormant? It would require acquiring a human host and then suppressing its primal genetic disposition to multipy and kill. Polio, like Smallpox, is not one of the five viruses that we know can go dormant. However, if it could go dormant, the current war torn environment would be the perfect time to wake up.
Finally, we have to consider that our assumption that it is non Zoonotic is incorrect. Somewhere in Gaza it found an alternate host and stayed alive waiting for what it knew would eventually happen. As we have done throughout our history, we started killing each other again.
Either alternative 2 or 3 would also explain how smallpox crossed the Atlantic ten centuries ago.
