John Naish

The machine disturbs a bat feeding in a banana tree causing it to flee.

The bat flies over a pig pen, dropping a piece of the fruit – which is gobbled up by a hungry piglet.

That piglet is destined for a restaurant in Macau where its carcass is prepared for cooking by the chef.

Called from the kitchen to meet a customer, he fails to wash his hands and greets the unfortunate woman with a friendly handshake.

And so she becomes Patient Zero, the first person to be infected with a lethal new virus – caused by the spontaneous merging of genes from pig and bat viruses.

Within weeks the virus has infected half the world and 25million people are dead – including Gwyneth Paltrow, the unfortunate Patient Zero – and Kate Winslet, playing an epidemiologist, whose corpse is buried in a mass grave. 

The US President, meanwhile, has been dispatched to a secret underground bunker.

That global pandemic was, of course, the stuff of science fiction as envisaged in the 2011 film Contagion. 

Yet the deeply worrying events in China suggest that this plotline may be uncomfortably close to the truth.

The Wuhan novel coronavirus, which has placed 56million people in 18 cities on lockdown and triggered a worldwide health crisis, may owe its existence to a single horseshoe bat which lived in a cave in the lush forests of the Hubei province in central China.

Scientists believe the creature, which is barely the size of a man’s hand, was eaten by a Chinese krait – a highly poisonous snake.

That was then netted by a hunter and brought to the huge live animal market in Wuhan city, where freshly slaughtered reptiles – along with wolf cubs, donkeys, badgers, hedgehogs, porcupines, camels and even koalas – are highly prized as delicacies.

But when that krait was cooked and eaten by a local family, the world suddenly became a more perilous place. 

For the tiny horseshoe bat carried a virus which jumped the species barrier into humans, for whom it can be fatal.

With the help of its new human hosts – and planes, trains and automobiles – coronavirus is now spreading across the planet.

Scientists are still fathoming just how the Wuhan coronavirus emerged, but this model of transmission – from bat to snake to dining table – is supported by two Chinese-born professors of microbiology and molecular genetics at Pittsburgh University.

Genetic analysis of the virus – also known as 2019-nCoV – shows mutations suggesting the virus evolved to infect bats first, and subsequently snakes.

In the 1930s, scientists in Trinidad showed that vampire bats can transmit rabies to humans. 

Since then more than 60 bat-borne viruses have been found that can also infect us. 

These include Ebola which, between 2013 and 2016, killed more than 11,000 people in six countries in West Africa.

Ebola-infected bats first passed the virus to African apes – probably via droppings – and then to humans after hunters ate the apes as bushmeat.

Our two most recent coronavirus pandemics were also the result of host animals becoming the stepping stones from bats to people. 

Studies show bats to be the original source of SARS (severe acute respiratory syndrome) which killed 774 people in the early 2000s.

It is widely believed that SARS jumped from bats into Asian palm civets in China. In November 2002, the virus first appeared amongst people working at a live animal market in the southern Guangdong province, where civets were being sold for food.

Similarly the World Health Organisation says that MERS (Middle East respiratory syndrome), which has claimed 850 lives since 2012, originated in dromedary camels. 

Viruses that jump from animals to humans are called zoonoses and were the cause of the world’s three biggest known pandemics – the Black Death, Spanish flu and HIV.

When an animal virus infects a human, it mixes with other established viruses and can acquire genes that facilitate better human-to-human transmission, increasing its infectivity – spreading by a cough or sneeze – and thus ensuring its survival by finding new hosts. 

Alarmingly, this appears to be happening with Wuhan coronavirus.

The risk of the rapid spread of such contagions from animals has been boosted by our relentless encroachment into the world’s forests and jungles, where we increasingly come into contact for the first time with unknown viral killers that have been evolving and incubating in wild creatures for millennia.

Climate change, too, is a factor as it forces some creatures to find and adapt to new habitats, perhaps closer to humans.

There are plenty of other new viral candidates waiting in the wings, guts, breath and blood of animals around us, and any one of these infections, along with countless as-yet-unknown zoonoses, could cause a global disaster beyond the worst nightmares of Hollywood.

Our hopes must lie, as ever, in science. In the short term this means quickly developing vaccines against the latest Wuhan coronavirus and the other viruses that will inevitably follow.

In the longer term, we must establish how creatures such as bats can harbour deadly infections but not be killed by them.

That secret, once unlocked, might save humankind from the greatest threat it faces – a pandemic caused by a highly contagious and lethal mystery virus. Let’s just pray it isn’t this one.

Compiled by Olalekan Adeleye

MailOnline