Talking about viruses means throwing in a lot of large mathematical values and big numbers — the extent of which most of our minds are unable to fathom. We know quiet a bit about people being infected with coronavirus. We we also see that while some are becoming sick, a lot more who are invaded / infected by the virus but are not getting sick.
It will not be an unreasonable or unscientific statement if we say that viruses probably don’t want to kill us. Killing the host is not in the best interest for the virus also. They want to peacefully live in their hosts, procreate and spread the community. These virus are here today inside our bodies are here after 3 million years of preparation and training in the form of evolution and selection. And they are genetically and proteomically the fittest, hence very apt at surviving and spreading in current zoonome. Only thing they want is to make our body their home and live without harming us much. We are great hosts for them — because there are seven billion of us and we live a social life — in close congregation — so if needed they can jump from one to another. We are their dream home!
Once they can safely reside in us — we are so many in number — they won’t have to look for new home- their only job will be to keep propagating — for millions of years! Exactly what four other human coronaviruses are doing for centuries.
Naturally and understandably, our body is home to innumerable viruses. A good count or number is impossible to deduct. We have 40 trillion bacteria in our body and usually we know that there are ten times more viruses in nature than bacteria. Hence it is assumed that there are 400 trillion viruses who call out body their home.
We have a peace treaty with these viruses, there is a longstanding ceasefire. We don’t fight each other. Many, if not most, viruses are helpful for us.
How can a virus be helpful? Before we discuss that let’s first talk about virus biodiversity in our body. We are still learning and our knowledge of human virome is still very incomplete. So far what we have identified that there are 53 different types of human viruses in our body and about 53000 types of viruses which are the viruses living inside the bacteria that live inside our body. We know this from gene sequencing study. Isolating them in culture medium has been an impossible job.
Those viruses in bacteria keeps bacteria population in our body under check and don’t let bacteria overwhelm us/ take over us! This is how some viruses are helpful for us.
Humans are mammals. Roughly there are about 6000 species of mammals. How many virus species each mammal carry? So far there has been one real study. A big group of scientists led by world top emerging infection scientist — Dr. Ian Lipkin went to Bangladesh — randomly selected a site — collected flying fox ( fruit bats) for throat swabs, collected urine and stool specimen. A total of 1800 samples! On average they found 58 viruses per bat. Almost all the viruses they identified were new to us. They isolated few bat coronaviruses and most other types of knows virus types. Based on that model we think that mammals have about 400000 different types of viruses, the number rises to 100 million types of we count all vertebrates, not only mammals!
But our land based virus is nothing compared to the viruses found in our oceans. Canadian virologist Curtis Suttle always use colorful / sensational allegories when he tries to describe the amount of viruses that reside in our ocean waters.
There are 10 to the power 30 number of viruses in our oceans. What does the number 10 to the power 30 mean? It’s a number that normal human brain like mine can’t process. Let me try to explain- if we line up all these marine viruses (100 micron in length on average) side by side that will stretch 10 to the power 28 Kilometers. Believe me that’s a very long distance — about 100 million light years long! Our galaxy is about 150,000 light years across! This line of viruses will span 60 galaxies! How far is the closest star system from earth? Proxima Centauri it is and it’s only about 4.2 light years away!! How much all these ocean virus weight? Their collective weight is equal to the weight of 75 million blue whales!
And about 10 to power 23 infections are happening every second in our oceans! Virus is the major determinant in the delicate echo balance and marine life cycle and are responsible of 50 % of planet’s oxygen production! In every liter of coastal water there are 10 million viruses. Overall in oceans there are 10 million times more viruses than stars in the galaxy!
So that’s about water / sea / river! What about the sky? Well, about 9000 feet above ground, in the sphere called troposphere, there is transcontinental air current above our weather system! Billions of viral and bacterial particles fly all the way to that high and do transcontinental travel for thousands of miles! And then they shower on us in billions! A single square meter of the planet’s surface could be showered with hundreds of millions of viruses — and tens of millions of bacteria — in a single day. These viruses are all over in the air around us. Luckily they are not the types of viruses that are pathogenic to us! Most can’t enter our cells!
Measles is a type of virus that may remain air suspended and travel to the far corner of the room staying suspended in air and may infect everyone breathing that air. So are Zoaster! They can fly in air and infect people. Whether SARS-COV-2 has that ability or not that remains as a point of serious contention. (Scientific Bangladesh will discuss that debate someday very soon)! Luckily Most virus doesn’t have that capacity to be airborne.
Viruses need receptors/ window or door in the hosts’ cell to enter the cell. Without that they can’t enter and infect the host. Once virus enters cells — it depends on the Virus how long it will take to start the symptom. Influenza virus symptom starts only on one to two days day after infection! On the other had it may take AIDS virus up to 18 years to start the symptoms!
Typically thousands or tens of thousands of coronaviruses need to enter the cells of nose / throats of a person to infect him/ her! But that number is nothing because a hundred million coronavirus particles could fit on the head of a pin. And although we read, worry, talk, discuss about how many days this virus can stay alive on what surface, we need to know that infection window is highest in the first ten minutes.
… to be continued
