Part I – Hitchhikers Extraordinaire

What breeds faster than you can think, hits you like a freight train, and has no mercy?

A virus, that’s what.

In this series of three articles, I am going to take a look at just how clever these little buggers are.  

I had my annual influenza booster last week. Winter is on its way, and I’m feeling worried. I caught long COVID-19 earlier this year.  I didn’t want to complicate things with a dose of flu, so I went to the chemist and got my shot. However, I found out that the version I got lacks the antigenic structure for this year’s virus.

It made me think just how clever and well-adapted these little guys are, and they don’t even have a brain!

We have brains, yet we are not well adapted to life or capable of surviving as well as these animals do.

Everyone on earth is aware of COVID-19. The latest pandemic (a worldwide disease) that has hit mankind. Over 7 billion people have been reported as having COVID, of which just over seven million have died.  Other viral diseases, like smallpox, killed over one billion people. Three hundred million of those deaths occurred in the twentieth century.

That is not the worst. Malaria leads in deaths from viruses, with nearly five billion. Tuberculosis follows, causing over one billion deaths, and then comes smallpox. They still run rampant in underprivileged countries.

Hitchhikers extraordinaire!

One of the main reasons why viruses are so potent is their ability to transmit undetected. Take COVID as an example.

Thanks to modern travel, COVID is the ultimate frequent flyer. A typical jumbo jet from Los Angeles or London carries nearly 400 people. COVID, the sneaky hitchhiker, invades someone’s body before boardinga plane. Then it goes to work.

It sets about infecting a whole load of people during the flight. When the plane lands, everyone gets off. By then, the virus has multiplied billions of times. Talk about working on a plane!

It has gone unnoticed, spread widely, and infected many who are unaware. They might believe they have jet lag or have had too much red wine or champagne. But now, they are set to meet even more people who can host these little buggers.

Before COVID-19, nearly 6 million people and 5,400 planes flew from Heathrow each month. In Los Angeles, over 3.5 million people and 26,000 planes passed through monthly.

Think about the cruise ships that fell prey to COVID; captive audiences all at sea (excuse the pun!) with nowhere to run. Pre-COVID (2018), the total number of people on cruise ships annually was around 28 million. Combine these two, and it’s clear how this little bugger spread fast and well. It’s the ultimate hitchhiker!

Perfecting the art of transmission.

Viruses in general have perfected the art of transmission. The Vikings may have spread the smallpox virus across Europe and beyond. It ended up killing 300 million people in the 20th century.

This disease is thought to have existed in the days of the Pharaohs. Traders carried the disease from Egypt to India during the 1st millennium BC. Historically, before a vaccine came about, roughly 3 out of every 10 people infected died.

This contributed to smallpox’s downfall. It was too aggressive, with a mortality rate over 30%.

Other viruses, such as influenza, kill only a small number of their hosts today. Around forty-seven thousand people die from influenza each year, most of them outside developed countries.

It has mastered the ability to infect and multiply in people before they get bedridden. Infected people spread the virus by coughing and sneezing on others. It spreads faster than a bushfire in January!

COVID also kills few of its hosts (about 2%). Seasonal influenza kills a bit over 1% of those infected. So, COVID is roughly twice as deadly as the flu.

Super Sleuth

You can’t see it, you can’t smell it, you don’t even know it is there! Viruses are so small, over 500 can fit within the diameter of a human hair. Most viruses are smaller than red and white blood cells.

Our body is usually able to block out particles that are greater than 10 microns. Viruses like influenza and COVID are 10,000 times smaller. So, they can easily be inhaled into your respiratory tract.

Many human diseases come from viruses that can “hide” in reservoir hosts. These animals don’t get the virus. But they can still spread it if a vulnerable host, like a human, appears.

There are over 200 different viruses that infect humans. The discovery curve shows that many human virus species remain undiscovered. Over two-thirds of human viruses can also infect animals and birds. Many have origins in non-human species.

One of the main culprits is bats. They seem to have a unique immune system that prevents them from overreacting, which helps them avoid getting sick. Bats are over 1,200 species and 20% of all mammals on Earth, and they harbor hundreds of different viruses.

You may be thinking, with so many viruses, how come bats don’t get sick?

They should be toes up with all the viruses they harbor!

In flight, a bat’s temperature rises a lot. It’s too hot for viruses to replicate well. Their heart rate can surge to more than 1,000 beats /minute. Bats have developed a very specialized immune system that does not ‘overreact’, so they don’t get sick.

Next time, I will look at viruses as the ultimate sex machines and replication geniuses.

Till next time,

Calvin