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Know the Enemy Part 1: Know the (microscopic) enemy, power in numbers and strength in diversity

It is said that if you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle.

―The Art of War by Sun Tzu

Chinese General, Military Strategist & Philosopher

Each of us is a singular representative of the human species. Likewise, each bacterium and virus in the human body and in nature is a discrete entity, representative of its species. In the human body, it is thought that bacterial cells outnumber human cells 10 to 1, or 100 trillion to 10 trillion. Although recent studies suggest less skewed differences, this does not take into account other microbes and the even more microscopic viruses housed in the human body. And so, in order to gain perspective and visualize the enemy, we will keep things simple.

These trillions (or quadrillions) of microbes are akin to an army of individual organisms within one human body. The human “microbiome” is a community of bacteria, fungi, viruses, bacteriophages (viruses that infect bacteria), and archaea (organisms that blur the microbe line and live in extreme environments) in the body. The human body is 100,000 times larger than a human cell with the exception of a human egg cell that is wider than a human hair and the 3 foot long sciatic nerves that course down from spine to feet. The human body is 1 million times larger than a bacterial cell, and a bacterial cell is 10 times smaller than a human cell. And, if you can imagine, the human body is 10 million times larger than a virus, and a virus is 100 times smaller than a human cell.

This begs the question as to why the uber-microscopic world has such a foothold in ours. Well, there is power in numbers.

As stated above, microbes outnumber human cells at least ten-to-one. As such, microbes heavily influence the human condition, from immune defense to neural network communication. The influence of viruses in particular is even more elusive. While bacteria and most other microbes are quarantined to their own quarters in the human body, viruses infiltrate human cells because they are unable to live outside of their host. After a virus invades, if it does not conquer, it hides in plain sight and lies in wait until its host is vulnerable. At that time, it colludes with its viral family and takes formation into a “Trojan horse,” attacking from the inside out.

Just as not all bacteria are pathogenic, or “pathological,” not all viruses are virulent or “violent” in nature. There are an estimated 1,000 bacterial species in the human body with 2,000 genes per species, or a composite of two million genes. This is 100 times the number of human genes estimated to be 20,000. The diversity of viruses in the human body is unknown, but just as they outrank bacteria in number, they presumably outnumber in diversity of species. From the era of the Human Genome and Microbiome Projects, the Global Virome Project has recently emerged in humankind’s attempt to gain the upper hand on the microscopic battlefield.

Now, one may ask how humans accomplish such great feats, some of which are literally otherworldly, but cannot defeat a rogue micro-villain.

Think again of the enemy: ten million times smaller than the human body and 100 times smaller than a human cell. Appreciate the technology needed to even fathom observation of the enemy. As a refresher, atoms (basic units of matter) are 1,000 times smaller than a virus. The atom’s constituents (protons, neutrons, and electrons) are 100,000 times smaller than their parent atom. This is the same size ratio as the human body to human cell: 100,000 to one. It follows that, if you throw yourself into the limbo of inception, the microscope needed to examine a human cell needs its own microscope to examine a virus, ergo the electron microscope. And as you know, observation rests just at the surface of knowing the enemy.

A virus is only ten to fifty times larger than a strand of DNA, the carrier of all genetic information. As such, viruses are defined by whether they are made of DNA or RNA. RNA is the mirror image of DNA that sends messages and signals to DNA outside of the cell core, or nucleus. Coronaviruses are a family of RNA viruses that resemble a corona, or crown, under an electron microscope. Their hosts are mammals and birds, and seven types of coronaviruses are known to infect the humans. Two viruses cause the common cold, one virus causes community-acquired pneumonia, and one virus causes bronchitis.

The other three coronaviruses are rare and sometimes fatal. The virus MERS-CoV causes the disease Middle East respiratory syndrome, or MERS. The virus SARS-CoV causes the disease severe acute respiratory syndrome, or SARS. And, last but certainly not least, SARS-CoV-2 causes the disease CoronaVirus Disease 2019, or COVID-19. The subtle point here is that a virus and disease are not synonymous. An enemy virus such as SARS-CoV-2 infects a host and, depending on a host of host defenses, causes or does not cause a disease such as COVID-19. In my book, Pandemic Manifesto: COVID-19 Basic Training From The Frontlines, previous knowledge of MERS and SARS, as well as several other viruses, are used to predict mechanisms of action and outcomes in COVID-19. As members of the same family, SARS-CoV-2 shares approximately 79% of its genes with SARS-CoV and 52% of its genes with MERS-CoV. Many of the genetic differences in SARS-CoV-2 compared to its viral kin are related to its enhanced virulent properties.

I digress. Indeed, the enemy is enormously small. But, as we now know, the most vulnerable amongst us are vastly outnumbered and under-diversified.


Farah Fourcand, F. (2020, August 20). Pandemic Manifesto: COVID-19 Basic Training From The Frontline. Author.

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