Is it likely to have another pandemic while still drowned in COVID-19? This is a very scary thought but not unrealistic or as improbable as one may think. Here is why.
As world population is growing, as we deplete more and more of the preciously saved Sun’s energy in the form of coal and fossil fuel, other species are being stressed. Why should we care? Because other mammals like bats and rats, when stressed, shed viruses that has never been exposed to human before. As you may already know, the origin of SARS-CoV-2, the virus that triggered COVID-19, has been traced to bats hidden in a remote cave in the Yunnan province in China far from any human dwellings. As shown in the figure below, other more recent outbreaks like SARS and MERS in 2002 and 2012 respectively are triggered by spillover of SARS-CoV-1 and MERS-CoV viruses by bats. The source of SARS-CoV-2 that causes COVID-19 is missing in the figure, which is now linked to a coronavirus from bats and the intermediate host is a mammal called pangolin, an engendered species.
If we think this is an accident and will soon fade like symptoms of flu, you are so wrong. Let us look into the history to get some perspective on such events.
The black death of 1347 that killed 75-200 million people across the world is caused by Yersinia pestis, a bacterium commonly found in fleas carried by rodents. Due to climate change in Asia rodents moved out from dried out grassland to areas inhabited by human, bringing with it fleas that acted as a conduit for Yersinia pestis between rat and human, triggering the great plague that travelled to the West from Asia via the silk route.
The plague of Justinian 541-549 AD, also caused by Yesinia pestis, killed 25-100 million over 200 years causing religious, social and economic upheaval in Europe. A comparison of the genomes of a modern-day Yersinia pestis with those that caused Justinian plague in 2013 nails the source of the bacterium to be Tian Shan, a system of mountain ranges on the borders of Kyrgyzstan, Kazakhstan, and China. This finding suggests that the expansion of nomadic peoples who moved across the Eurasian steppe, such as the Xiongnu and the later Huns, had a role in spreading plague to West Eurasia from an origin in Central Asia.
Plague is a serious bacterial infection that is transmitted primarily by fleas, which has fed on small infected rodents or humans handling animals. There are three types of plague: bubonic affecting lymph nodes, septicemic that affects blood and pneumonic affecting the lung. Of these, pneumonic plagues is the most dreadful as it can infect human to human just like COVID-19. It can be deadly if not treated promptly with antibiotics. What scares me the most is the vulnerability of COVID-19 survivors with compromised lung from COVID-19.
Among other diseases that devastated humanity is malaria and smallpox. In Guns, Germs and Steel, Jared Diamond has given a chilling account of the impact of diseases crossing the Atlantic along with slave trade to the Americas. These diseases killed the invadors and the invaded with equal ferocity. Slaves with immunity to the diseases of their homeland survived in big numbers and became the most important labor commodity in building America, providing justification for even more slave trade and endless onslaught by diseases. In the book Mosquito, Timothy Winegard described the devastation caused by mosquitoes to native Americans. Malaria and other mosquito borne diseases, including dengue and yellow fever, is known to have penetrated deep into Americas faster than the invaders could travel. Native Americans were killed by tens of millions even before they could set their eyes on a single white man. Tens of millions of native Americans died by mosquito borne diseases rendering the thickly populated land, estimated to be 100 million at the time Columbus arrived, empty for invaders to simply walk in. It is really mosquito that conquered Americas. I wonder, who will be occupying the property I own in Marin if mosquito did not side with the invaders.
Getting back to the point, human migration, invasion, trade and, more recently, global economy has created a perfect storm to repeat history several times at an incresaing frequency. As convincingly said by Thom Hartmann’s in his book The Last Hours of Ancient Sunlight, population exploded from a shear 500 million worldwide in the year 1000 to 5 billion in 1800 because of exploiting ancient sunlight in the form of coal and fossil fuel. Like inherited savings account, human started spending more sunlight everyday than what is falling on earth every day. This is akin to spending more than your earnings by borrowing from your parents, which unlike credit cards, is not only interest free but is also principal free. Keeping with the pace, in the last 200 years we added another 2.5 billion people. It is shocking to note that India had only 300 million people when I was a child.
This growth in population and its uncontrolled dependence on ancient sunlight is leading to climate change. Although this is contested, simple commonsense and a basic knowledge of science will convince you otherwise. Not only are forests critical to store Sun’s energy that fall on us today, they also have the potential to convert the large amounts of C02 that gets dumped in the air by our excessive dependence on coal/oil, back into oxygen. Apparently, each tree in the Amazonian jungle provides 40 acres of leaf surface for this conversion. Nature is beautiful!
Politics has gotten the worst of us. Instead of educating people, we shamelessly, use their ignorance about science and nature to our political advantage. According to Thom Hartman we have extracted 1300 billion barrels of oil so far and it is estimated that 1500 more barrels may be left. It should be mentioned that the first 1300 barrels were low hanging fruits. It is not clear if the extraction of remaining barrels will even be cost effective. At the current rate of consumption and growth in population our great-grandchildren will inherit no coal or no oil. We will perhaps hear their curses and turn helplessly/hopelessly in our graves.
Mammals shed when stressed. Bats are home to a large number of commensal viruses that are not infectious to human. However, if we do nothing about the climate change, mammals like bats, which are sensitive to mild change in temperatures, can shed viruses. These events are called spillover. When bats continue to be stressed and continue to spill from human activities, the odds of the viruses infecting other mammals, say farm animals, become high. If animals get sick, viruses get opportunities to multiply in large numbers acquiring new mutations making them infectious to other animals. This can go on for several years without any harm to human. However, mutation within the animals could continue for several years until a day when a human, handling the animal, unfortunately get infected by a mutated version making him sick. At this point, the virus may still not be ready for human to human transmission. But the virus now has opportunity to mutate within infected human and select for mutations that can make human to human transmission possible, setting an epidemic and then turning into a pandemic like COVID-19.
COVID-19 is no different than other pandemics in the past. It killed more people in a distant, more vulnerable population. As we get ready to handle this crisis, I read an article in New York times regarding rats getting stressed from lockdown of restaurants (https://www.nytimes.com/2020/05/24/us/cdc-coronavirus-rats.html). Anyone who visited NYC would know the menace caused by rats surviving on waste from the restaurants. You are right, I am worried about starving rats. Not joking! The stressed rats may start shedding, who knows what. Their lowered immune system from lack of food also make them vulnerable and a carrier of other diseases including viral, microbial or parasitic.
Where is the Pied Piper when we need him the most?
