By now, most people probably know that a coronavirus is behind the Covid-19 pandemic.
Many also know that a ‘pandemic’ implies a disease that’s gone global - as opposed to a more localised epidemic or outbreak, that an ‘R’ means ‘reinfection rate’, and that social distancing, lock-downs (definitely those!), and face-masks are all part of monitoring and manhandling such maladies back under control.
What is Coronavirus?
In this article, though, we are going to take a few steps back and peer into the more-than-slightly murky waters for the possible origins of Covid-19.
Coronaviruses get their name because of the spikey coat of proteins that surround their genetic core, and that looks a little like the fluffy array around the sun - a ‘corona’. Likewise, blood vessels that circumnavigate the exterior of our hearts constitute our ‘coronary’ arteries.
While there are very many different coronaviruses, seven basic types are known to affect humans - four of these are associated with common colds, and three are serious. The three serious ones are SARS, MERS and SARS-2 or ‘Covid-19’. All three are essentially ‘severe acute respiratory syndromes’ - hence ‘SARS’ -diseases, with ‘MERS’ meaning Middle-East respiratory syndrome.
That said, when first identified, the new SARS virus was regarded as a single entity, whereas closer investigation suggests that several variations seem to be emerging - either due to better understanding (good) or rapid viral mutation (not so good).
Where did Coronavirus come from?
So, that’s what coronaviruses are and what at least some of them can cause. But from where did these pestilential pathogens originate?
Well, for the 2002 - 2003 SARS pandemic it is thought that horseshoe bats sold at wildlife markets in Asia may be somewhere towards the root of that problem, and perhaps that bat-borne virus transferred into civet cats (also sold at markets) - a process called ‘spill-over’, and thence to humans.
The 2012 - 2013 MERS pandemic was probably a bat-to-camel-to-human spill-over. And SARS-2/Covid-19 a bat-to-pangolin (a scaly mammal) and onwards.
Did Bats cause Coronavirus?
But while a kind of guilty-looking coronavirus has been found in bats that is genetically very similar to the Covid-19 pathogen, it is not quite the same as finding the virus. So where is it? Truth is, we don’t yet know.
Normally, it would take a fair amount of time for the suspect bat coronavirus to change into the type we have with Covid-19, but it appears that things either evolved unusually quickly or the real culprit is loitering in the shadows - but wherever it is, it is likely somewhere in or around the ghastly wildlife markets that have spawned so many historical health horrors.
Of course, there are circulating alternative theories that the virus accidentally made its way out of a government laboratory in Wuhan, China. But both the lab and an independent team of scientific investigators from one of the world’s leading institutions have refuted that suggestion.
Bats carry ‘corona’
Anyway, why are bats talked about so much in the Covid-19 and other crises? How can these immensely cute and mysterious creatures - the only flying mammals - get to be so notorious in the world of epidemiology?
Several reasons really. Bats eat a wide variety of invertebrate prey (e.g. insects and spiders), which in more tropical regions can themselves harbour a raft of viruses. Predators - here the bats - need strong stomachs, and beyond that strong immune systems to avoid getting sick, let alone passing it on to others in their group and wiping out the lot.
Having such a strong immune system not only means that bats can enjoy normal lives, and remain interactive with many other species, but also the gamut of viruses that ‘try it on’ with bats get nowhere other than stockpiled and carried around to those with less formidable constitutions - which is just about everything.
Then, of course, bats live in high-density populations so they can’t be social-distancers. Often, they also roost in communal caves and other somewhat enclosed spaces, where breaths, airborne debris and even latrines are everywhere one turns - making French motorway toilets seem like an intensive care unit.
This is probably why bats are known for carrying around bugs that do them little to no harm, but which can cause a bunch of really serious diseases in people including, Ebola, Marburg, Nipah and Rabies (although even bats can’t escape that one). All these diseases make Covid-19 look like a head-cold.
Whose fault is it really?
However, we cannot, and must not, blame bats for Covid-19. If, as suspected, bats are a significant part of the infection chain, then it’s likely the only reason we face a bat-linked pandemic is because people have been encroaching into their territory, and then netting them up to face gruesome handling and slaughter for entirely spurious soups and meats on a stick.
Unfortunately, such penchants for culinary curiosities have been warned against for decades, but too little has been done, and too late - and today many people are literally sick of or dead due to tardy governmental responses.
In the next article, we will be looking at ‘people and viruses, evolution of viruses, viruses in the body, immunity, and disease’. Until then, stay well, stay safe!
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