Written in 2016.
The illegal trade in wild-animal meat could cause the next global pandemic
September 29, 2016
By
Akshat Rathi
Senior reporter
At first glance, there seems to be nothing unusual about Ridley Road Market. Like any other London market, there are stalls selling fresh fruit and vegetables, cheap electronics, artificial jewelry, and other bits and bobs.
Then, the smell hits you. Behind the makeshift stalls are butchers’ shops. There are a dozen of them within 300 feet, each displaying a panoply of meats and hung carcasses. There are beef ribs, pork shoulders, lamb shanks, chicken thighs—all the standard offerings found at most butchers. But there are also more unusual cuts like lamb heads, ox kidneys, cow hooves, and others I don’t recognize.
Some of the butchers show questionable hygiene: they handle meat with bare hands, blood oozes out onto shop floors, and flies settle on some of the meat. Most things are unlabeled. None of this deters shoppers, but it’s not what I expected from a market that has already been under the spotlight for selling smuggled bushmeat.
Bushmeat is a catchall phrase for the meat of wild animals found in the tropics, principally West and Central Africa. It is illegal in the UK and many other countries, which were forced to adopt strict rules following disease outbreaks that were linked to the import of wild meat.
Humans have, of course, hunted and eaten wild animals for hundreds of thousands of years. Before we invented agriculture and domesticated animals, wildlife was a key source of nutrition (and still is in some parts of the world). Without such hunting, we would never have become the planet’s dominant species.
But the equation has changed. There are now too many of us and too few of them.
Worse still, the imbalance we’ve created has opened us up to diseases that would have otherwise remained in wild animal “reservoirs.” If a specific set of circumstances align, an infectious disease that jumps from an animal to a human can spread rapidly and kill indiscriminately in our hyperconnected world.
Hosting deadly viruses
Infectious diseases are caused by pathogens of all shapes and sizes—from single molecules called prions to multicellular parasites like tapeworms. These pathogens can lead to a range of illnesses, from the mild, like the common cold, to the devastating and fatal, like rabies. Together, infections
cause one in five deaths every year, and make billions of us ill.
Fortunately, not all pathogens are capable of creating the next pandemic. Black death, which killed a third of Europe’s population in the 14th century, was caused by the bacterium
Yersinia pestis. With modern antibiotics, we generally don’t need to worry about bacteria —at least not until a superbug resistant to all antibiotics finds a way of spreading.
But some infections have the potential to cause what scientists simply call the next big one. “Next” because this sort of thing has happened before—think about the 1918 Spanish flu pandemic—and “big one” because the scale and cost to society can be tremendous. The next big one could be a known threat, such as Ebola or bird flu, or it could be something you’ve never heard of.
The experts I spoke to agree that the agent most likely to cause the next pandemic will be a virus—more specifically, an RNA virus. These viruses are the bêtes noires of infectious-disease specialists, and are responsible for influenza, MERS, Ebola, SARS, polio, and HIV, among others.
They also cause lesser-known diseases with the potential to become the next big one: Marburg, Lassa, Nipah, Rift Valley fever, and Crimean–Congo hemorrhagic fever to name a few. (In
early September a man died from Crimean–Congo hemorrhagic fever in Spain, reportedly the first case in Western Europe in someone who hadn’t travelled to areas affected by the disease.)
Compared to the cells that make up living things, viruses are lean. They carry only as much genetic code as needed to enter a cell and take over its machinery. And RNA viruses lack the genetic code to make an error-correcting enzyme called DNA polymerase. This means that they suffer many times the mutation rate of any other kind of organism.
Such a high mutation rate would be a curse for a large organism, but for RNA viruses, it is a boon. Most mutations will render a virus less powerful, but every so often one will give it a nasty new power, say the ability to be more harmful to a new host. If such an evolved virus were to find a new host, it could unleash a new epidemic.
The other thing that experts are quite sure about is that the next big one will be a zoonotic disease—one capable of jumping from animals to humans. The fear of such an event, often called a “spillover,” is why bushmeat gets a bad rap.
Unlike smallpox and polio, which have been eradicated and nearly eradicated respectively, zoonotic diseases cannot be entirely wiped out—unless we can also destroy all the species that serve as reservoirs for these pathogens. Black death, Spanish flu and HIV—causes of the three biggest known pandemics—are all zoonotic diseases, and so, almost certainly, will be the next big one.
In 2015, the World Health Organization (WHO) published a
list of the top emerging diseases that are “likely to cause severe outbreaks in the near future.” It’s no coincidence that all the diseases on the list are zoonotic diseases caused by RNA viruses, which turn animals—mostly wild ones—into reservoirs to hide in.