(CN) — Here’s an unsettling possibility: The deadly coronavirus infecting millions of people around the planet may turn out to mark the onset of an age in which a natural world under siege from human activities injects more new diseases into humanity’s ever-more-globalized bloodstream.
Scientists are warning that climate change, deforestation, population growth, industrial farming and globalization are creating conditions for more viruses like the novel coronavirus to emerge from obscure recesses of nature and infect humans. Scientists call this a spillover and they say the world needs to prepare for more of them.
“Probably those viruses that we are getting now have been there all along in those forests, in the permafrost,” said Jean-Michel Claverie, a professor of genomics and bioinformatics at the Aix-Marseille University School of Medicine in France, in a telephone interview with Courthouse News.
“Now just because we are getting onto those territories, we are catching the virus too,” he said. “We are now in places where we should not be.”
In his laboratory in southern France, Claverie is studying ancient viruses buried for millennia under the permafrost in Siberia. They are unlike any viruses previously known and scientists warn these ancient viruses could be released as the planet warms and thaws Siberia’s frozen ground.
As yet, scientists say there’s no known case where an ancient virus under the permafrost has infected humans. But, they say, it’s possible a disease that once killed Neanderthals may re-emerge and infect humans.
“One reason [no one’s been infected] is that there is not much population in such an area, but that doesn’t mean there are no viruses which could be dangerous to humans,” said Chantal Abergel, a virologist at the French National Center for Scientific Research. She studies these ancient viruses with Claverie, her husband. In reviving ancient viruses, the French researchers said they are finding microbes likely capable of infecting animals and plants.
Viruses lying dormant in the frozen grounds of Siberia may pose a threat, but it’s the millions of viruses already circulating among animals that present the most immediate danger of spilling over to humans and then spreading around the world — as the novel coronavirus causing Covid-19 is doing. Viruses, unlike bacteria, are so dangerous to humans because effective medicines and vaccines to combat them are extremely difficult to concoct.
Of course, humans have always been vulnerable to epidemics — most often caused by zoonotic diseases, linked to animals — and died from them.
“You might get the impression from looking at Western newspapers that there are sort of one or two big epidemics a year and that’s it,” said Dr. Jimmy Whitworth, a physician and infectious disease specialist at the London School of Hygiene and Tropical Medicine, in a telephone interview. “Well, that’s very far from the case. If you look over the last 40 to 50 years, you’ll see epidemics reported everywhere all the time.”
At any one time, he said the World Health Organization’s Africa office is investigating dozens of outbreaks. “So that gives you a sense that this is all around and everywhere,” he said.
While it’s true that humanity has always been susceptible to epidemics, today disease outbreaks spread much more easily and quickly around the world as global trade and travel increases.
“Pandemics are increasing in frequency because of globalization,” said Christine Kreuder Johnson, an epidemiologist at the University of California, Davis, and a specialist in emerging diseases, in an email.
“We changed the conditions for those viruses to travel,” Claverie said. “Before, it was just traveling by foot with people who got infected. But now those viruses are traveling by plane and in much bigger populations, in supermarkets, in malls, and so this makes life much easier for those viruses.”
He said the HIV/AIDS virus, identified in the 1980s, tells the story. The virus has infected 75 million people since the epidemic began and killed about 32 million people, according to WHO figures.
“We thought the HIV epidemic started in the ‘70s, but probably it started centuries ago. But it was probably only killing people in a small village in the bush and nobody even knew about it,” Claverie said. “But then the virus spread beyond this small village and got into New York, London, San Francisco.
“It was a monkey virus and if nobody had ever eaten a monkey we would never have had HIV spreading in the human population,” he said.
Since then, a string of other zoonotic transmissions have taken place and caused major epidemics.
In 1997, the world was spooked to discover an influenza strain found in birds in Asia had been transmitted to humans in Hong Kong. That avian flu virus, known as H5N1, continued to spread globally, causing 455 deaths since 2003, according to WHO figures. The virus still poses a threat.
A few years later, in 2002, people in China fell sick after becoming infected with a new coronavirus found in bats. That outbreak, known as SARS, killed about 800 people. The virus is believed to have been transmitted to humans through consumption of civets. It apparently disappeared after 2004.
Another coronavirus capable of infecting humans emerged from camels in the Middle East in 2009. This infectious disease, known as MERS, was not transmitted easily between humans, and that helped contain its global spread. In all, WHO figures link about 860 deaths to the disease.
In 2014, the West African nation of Guinea saw a major outbreak of the Ebola virus that spread to neighboring Liberia and Sierra Leone, killing more than 11,000 people. The disease is believed to be linked to fruit bats and it likely infected humans through the consumption of bushmeat.
The Democratic Republic of the Congo is fighting an outbreak of Ebola today. Scientists believe Ebola outbreaks may also be linked to deforestation.
Another epidemic hit in 2015 when the Zika virus spread in the Americas. The virus is spread by mosquitoes but also between humans through sex and blood transfusions and from mothers to unborn children. The virus also appeared in Oceania and Asia. It can cause fever, affect the nervous system and cause birth defects in newborns.
Besides the rapid spread of new diseases, scientists say human activities such as deforestation to make way for industrial farming and mining operations likely are contributing to the emergence of new pathogens. Cutting down forests also creates ideal breeding grounds for mosquitoes carrying diseases such as Zika, malaria, dengue fever and yellow fever.
“As industrial agriculture expands out into the hinterlands it puts pressure” on exotic species and small farms, said Rob Wallace, an evolutionary biologist, in an interview with The American Scholar, a quarterly magazine. He did not respond to messages seeking comment.
“The Amazon is a huge reservoir of viruses,” David Lapola, a global change ecologist from the University of Campinas in Brazil, told Agence France-Presse. “That’s one more reason not to use the Amazon irrationally like we’re doing now. We’d better not try our luck.”
Wallace said that as large farms move into wild forests there’s a growing risk of viruses circulating in wild species to spill over into humans because of increased contact.
Wallace believes vendors of wild animals are being pushed ever deeper into forests to supply buyers in cities and that too increases the chances of new viruses entering the human food chain and infecting people. He said the trade in wild species has grown and even become industrialized, leading to more risk of a spillover of animal diseases as wild foods are sold around the world.
“We’ve developed an agricultural system in such a way that we have a direct pipeline from the deepest reservoirs of pathogens in the forest directly right into the city,” he said.
Brian Chappell, an expert on the illegal trade in wildlife at the University of Portsmouth, said wet markets in Asia and Africa where wild animals are sold pose a serious risk. In Asian markets, wild animals of all kinds, from snakes to bats, are kept alive and slaughtered before sale to customers. This allows viruses to spread from one species to another, experts warn.
“If wet markets persist, there is potential for heightened risk for the emergence of new viruses and more lethal viruses and the sources of future pandemics,” he said in a telephone interview. “To quote the Wildlife Conservation Society: ‘These are perfect laboratories for creating opportunities for these viruses to emerge.’”
Wet markets sell fresh meats, produce and other perishable goods, as opposed to dry markets that sell industrial products.
Since the coronavirus pandemic began, pressure has built on China to better regulate its wet markets and even close them. But wet markets are found throughout Asia, and the WHO, among others, say they are a vital source of food for many people.
Chappell said it is possible the demand and supply of wild species will decrease after the Covid-19 pandemic. Scientists are looking into whether the new coronavirus may have been transmitted from bats to pangolins sold at a wet market in Wuhan.
Meanwhile, in the wilds under assault from human development, Wallace said animals are “not rolling over and dying” as their habitat is threatened. They are adapting to the changes in the landscape and learning to live with humans. For example, he said strains of avian influenza infecting commercial poultry stocks in North America have been traced to wild waterfowl adapting to the loss of wetlands and moving into cropland.
Another example are Ebola-carrying fruit bats in Africa, he said. They have adapted very well to the wide-open predator-free spaces provided by palm tree plantations spreading in parts of Africa. This has increased the “interface with humans” and the chances of a spillover, Wallace said.
Add climate change to the mix. As the planet warms, insects carrying disease are spreading more widely and their numbers are increasing. Droughts are getting worse and displacing people who may be become refugees vulnerable to infectious diseases and more likely to spread illnesses.
“There are various ways in which climate change can be a driver of epidemic,” Whitworth said. “It’s not the direct driver; it does it indirectly through other causes.”
Where will the next dangerous virus come from? That may be impossible to know.
The submicroscopic universe of viruses is awesome in its variety. There are more viruses than any other type of living organism on the planet. They outnumber bacteria, animals and plants and help keep balance in nature. They are everywhere and they’ve been around since life began on the planet, likely playing a vital role in the early stages of evolution.
“There are so many viruses that we don’t know about in the environment,” Claverie said. He said new viruses are routinely infecting humans but unlike the new coronavirus they are not as infectious, dangerous and certainly not as lethal, so they go unnoticed.
Despite the danger of future pandemics, he doubted humans will stop exploiting the planet.
“It is basically impossible, because of the growing human population which needs new territory to expand; we need to also expand the economy, we need to find new resources,” he said. “Frankly, I am not that optimistic about the possibility of not encroaching anymore on wildlife and wild territories.”
Presented with such a future, Claverie said the best course of action is to collect as much information as possible about the “unknown viruses in those unknown places.”
He said it is best to “be prepared just in case one of those viruses reveals itself as a possible pathogen for humans.”
The work to find and catalog the universe of potentially dangerous viruses has accelerated in recent years.
One major global virus-hunting project, called PREDICT, was funded by the U.S. Agency for International Development and since 2009 its researchers have collected more than 14,000 biological samples from animals and identified about 1,200 viruses, including more than 140 new coronaviruses. Although funding for PREDICT has dried up, USAID is developing a similar project called “STOP Spillover.”
Scientists around the world are doing similar work and catching wild animals such as bats to identify the viruses they are carrying. In the meantime, an initiative called the Global Virome Project is seeking to catalog all the viruses in wildlife that pose a threat to humans.
“You never know what the next epidemic is going to be; you don’t know when it is going to be; you don’t know where it is going to be; and you don’t know what it is going to be,” Whitworth said. “So the more we know about what’s out there, then the better able we are to prepare.”
But with millions of unknown viruses in nature, Claverie and Abergel said efforts to find the next dangerous virus before it emerges in the human population may be next to hopeless.
“It seems very impossible even with a big-data approach to map all those [viruses] and make any kind of prediction on which of them will be dangerous in the future,” Abergel said.
Claverie said scientists may become better at predicting potentially dangerous viruses that are similar to those that have already afflicted humans, such as coronaviruses and strains of HIV and Ebola.
“But there are so many viruses that we know nothing about,” he said. “It seems very difficult to predict the emergence of a truly new virus.”
The dilemma posed by viruses is that they are not easy to squash with medicine due to the sheer plethora of them and because they are so prone to mutation. By comparison, many harmful bacterial infections are treated with antibiotics, though there’s growing concern about the number of bacteria becoming resistant to antibiotics. When it comes to viruses, humans are much more vulnerable.
“Most bacterial infections are highly sensitive to antibiotics and it seems totally crazy that we don’t have any kind of comparable drug for viruses,” Claverie said. “Viruses are a real problem because we cannot kill them with penicillin or any kind of antibiotic. So definitely there is a real need for a serious effort in trying to develop generic antiviral drugs.”
Now, as the coronavirus pandemic batters humans, the drive to develop antiviral drugs is in warp speed as billions of dollars are spent on finding drugs and vaccines to tackle Covid-19.
“Clearly, there is a lack of serious long-term research in developing antiviral drugs,” Claverie said. “Every time we have a new crisis there is a little bit of money invested toward that and as soon as the crisis disappears, the money disappears. So we are tremendously late compared to the bacterial arsenal we have with antibiotics.”
It is possible the pandemic will spur long-term and exhaustive research to develop generic drugs capable of targeting mechanisms common to wide ranges of viruses. But finding such drugs will be difficult, Claverie said, because there are more than 100 families of viruses, all of which tend to replicate themselves differently. For example, science has come up with effective drugs to treat HIV, but those drugs cannot be used to treat other viral infections.
“This is why this research is late compared to antibiotics,” Claverie said. “This is a difficult challenge, to find a generic drug for viruses.”
Likewise, it will be difficult to find vaccines that work against all sorts of viruses, Abergel said. “If you have a vaccine, it will be against one virus, not a population of viruses.”
Whitworth agreed and said it is highly unlikely to find a vaccine capable of protecting people against viruses in general.
“You’d essentially have to find some common Achilles heel of all viruses,” he said. “That you’d be able to knock them out without affecting mammalian cells — so knocking out humans at the same time — I think the chance of that happening is very remote.”
It may prove extremely difficult even to find a safe vaccine that works to prevent infection from the new coronavirus, Claverie said.
“It is crazy to see the media say: ‘OK, we will have a vaccine in six months.’ Of course not. Even if a vaccine works very well experimentally in the lab, the time it will take to verify that it has no important side effect will be much longer than that. It will probably be years. We have many years, I would say.”
Considering the threats posed by the emergence of new diseases, Whitworth said the world needs to be better prepared for future diseases that cross borders and spread globally. He said that means investing in research, stocking up on medical equipment, helping poorer countries boost their health systems and taking the threat of a pandemic seriously.
“The only thing you can do really is try to predict,” he said. “That’s by surveillance [for new viruses], and by being prepared, and have a plan about what to do if it happens, and having a vaccine readily available or therapeutic drugs.”
He added: “I think, to be honest, quite a lot of lip service has been paid to [preparedness] in the past.”
Courthouse News reporter Cain Burdeau is based in the European Union.