Rolling Stone

DEADLY CLIMATE

Covid-19, Zika, Nipah virus, Ebola, dengue: How the climate crisis is ushering in a new pandemic era, and why we’re woefully unprepared for what’s to come

- BY JEFF GOODELL ILLUSTRATI­ON BY JASON HOLLEY

Jennifer Jones spent most of her summer at home, as so many of us did, trying to avoid the plague. Jones, 45, lives in Tavernier, a community in the Florida Keys just south of Key Largo, and spent a lot of the Covid shutdown in her yard, puttering around with plants. At some point, a mosquito landed on her. That’s not unusual in Florida, and Jones doesn’t remember this mosquito bite in particular. But it was not a garden-variety backyard mosquito. It was Aedes aegypti, an exquisitel­y designed killing machine that is one of the most deadly animals in human history. By one count, half the people who have ever lived have been killed by mosquito-borne pathogens. Aedes aegypti, which first arrived in North America on slave ships in the 17th century, is capable of carrying a whole arsenal of dangerous diseases, from yellow fever to Zika. The mosquito could sense the heat of Jones’ body and smell CO2 on her breath from more than 30 feet away. It landed on her exposed flesh, likely her arm or lower leg. The mosquito was a female — only females drink blood, which they need to produce their eggs. It worked quickly, knowing, in the genetic coding of its insect brain, that the longer it lingered the less likely it was to survive. First, it spit on Jones’ skin to numb it so she wouldn’t be alerted to the bite. Then it plunged its syringe-like proboscis, which is actually a sheath containing six needles, into Jones’ skin. It probed around until it found an ideal place to tap into a blood vessel. Then it inserted two needles, each one serrated like a carving knife, to saw a hole in Jones’ flesh. Two more needles pried the hole open, which allowed it to insert what looks like a tiny hypodermic syringe into Jones’ blood vessel. And here is the important part: As it sucked out the blood, the mosquito spit its own saliva into Jones’ veins, which contains an anticoagul­ant that prevents the blood from clotting at the puncture site. In this case, it also contained a virus that causes a tropical disease called dengue fever. When its appetite was sated and its belly full of blood, the mosquito flew off.

The word “dengue” most likely comes from the Swahili phrase “Ka-dinga pepo,” meaning “cramp-like seizure caused by an evil spirit.” Dengue is also known as “breakbone fever” because it feels like your bones are breaking when you have it. It has been around for centuries, and is most common in Asia and the Caribbean. According to the World Health Organizati­on, before 1970, only nine countries had severe dengue epidemics. Since then, it has increased thirtyfold, making it endemic — that is, permanentl­y embedded in the local mosquito population — in 128 countries. The WHO recorded 4.2 million cases of dengue in 2019. As the world warms, making more of the planet comfortabl­e for heat-loving Aedes aegypti, the mosquito’s range will expand northward, and to higher altitudes. By 2080, one recent study estimated, more than 6 billion people, or 60 percent of the world’s population, will be at risk for dengue. “The fact is, climate change is going to sicken and kill a lot of people,” says Colin Carlson, a biologist at the Center for Global Health and Security at Georgetown University. “Mosquito-borne diseases are going to be a big way that happens.”

It took a week or so for the virus to do its work. Once in Jones’ bloodstrea­m, it latched onto her white blood cells and began replicatin­g. She was watering plants when she felt lightheade­d, and then developed a fever. “I knew something weird was going on,” she tells me. Rashes. Pain behind her eyes. And bone-break ache in her joints. “I felt like I was a 99-year-old lady who had been hit by a truck,” she says. In rare cases, dengue can escalate to brain swelling and bleeding, which can be fatal (about 10,000 people a year die from dengue). But Jones was lucky. The pain and fever faded after four or five days, and she was almost recovered when her son called her to his room to point out the red splotches on his skin. As soon as she saw them, she knew: dengue.

As it turned out, the Florida Keys, already hit hard by the coronaviru­s, was in the middle of a dengue outbreak too.

Covid-19 likely emerged from the wilds near southern China, then found residence in horseshoe bats before making the jump to humans. The virus, as of this writing, has infected 63 million people and caused 1.5 million deaths around the world. The global economic impact of the pandemic was estimated at $8 trillion to $16 trillion in July 2020 — it may be $16 trillion in the U.S. alone by the fourth quarter of 2021 (assuming vaccines are effective at controllin­g it by then). The amount of human suffering this tiny microbe has caused is incalculab­le: lost loved ones, vanished jobs, broken families, and lingering sickness from a virus that will eventually retreat but will never disappear.

And yet we got lucky. “It could have been much worse,” says Scott Weaver, director of the Galveston National Laboratory in Texas, one of the top viral-research centers in the country. Compared with other pathogens out there, Covid-19 is relatively docile. It is an easily transmissi­ble virus that is far more deadly than the flu, and has mysterious long-term effects. But it doesn’t kill three out of four people it infects, like the Nipah virus. It doesn’t cause people to bleed out of their eyes and rectums like Ebola. “Imagine a disease with 75 percent case fatality that is equally transmissi­ble,” says Stephen Luby, an epidemiolo­gist at Stanford University. “That would be an existentia­l threat to human civilizati­on.”

The Covid-19 pandemic is often compared to the 1918 influenza, which killed at least 50 million people globally. But it is perhaps more accurately seen as a preview of what’s to come. “We have entered a pandemic era,” wrote Dr. Anthony Fauci of the National Institute of Allergy and Infectious Diseases in a recent paper he co-authored with his NIAID colleague David Morens. The paper cites HIV/AIDS, which has so far killed at least 37 million, as well as “unpreceden­ted pandemic explosions” of the past decade. It’s a deadly list, starting with the H1N1 “swine” influenza in 2009, chikunguny­a in 2014, and Zika in 2015. Ebola fever has burned in large parts of Africa for the past six years. In addition, there are seven different known coronaviru­ses that can infect humans. SARS-CoV spilled over from an animal host, likely a civet cat, in 2002–03, and caused a near-pandemic before disappeari­ng. Middle East respirator­y syndrome (MERS) coronaviru­s jumped from camels to people in 2012, but never found a way to spread efficientl­y among humans, and died out quickly. Now we have SARS-CoV-2, the virus that causes Covid-19.

The reasons for this new era of pandemics are complex, but as Fauci and Morens point out, one of the main drivers is the climate crisis, which is shaking up the natural world and rewriting disease algorithms on the planet. Thawing permafrost in the Arctic is releasing pathogens that haven’t seen daylight for tens of thousands of years. The Vibrio bacteria that causes cholera, a diarrheal disease that haunted big cities like London and New York in the 19th century and still kills tens of thousands each year, thrives in warmer water. An even more deadly strain of the same bacteria, Vibrio vulnificus, while rare, has been detected more and more frequently in bays and estuaries on the East Coast, particular­ly around Chesapeake Bay. Vibrio vulnificus, if you happen to eat shellfish, might give you a bad stomachach­e (in rare cases, it can be fatal). If the bacteria gets in a cut or wound, however, it becomes a flesh-eating horror and kills one in five people who come in contact with it.

But the biggest impact may be on the emergence of new pathogens from animals. Through intensive agricultur­e, habitat destructio­n, and

rising temperatur­es, we are forcing creatures to live by the cardinal rule of the climate crisis: adapt or die. For many animals, that means migrating to more hospitable environmen­ts. In one recent study that tracked the movement of 4,000 species over the past few decades, as many as 70 percent had moved, almost all of them seeking cooler lands and waters. Some animals have made big leaps. Atlantic cod have moved more than 120 miles per decade. In the Andes Mountains in South America, frogs and fungi species have climbed a quarter mile higher over the past 70 years. In Alaska, hunters are discoverin­g parasites from more than 950 miles southeast in Canada, alive under the skin of wild birds (tiny parasites adapt better to rapidly changing temperatur­es than large animals). Great white sharks are turning up as far north as Maine. “A wild exodus has begun,” writes Sonia Shah in The Next Great Migration. “It is happening on every continent and in every ocean.”

During this wild exodus, these animals are likely to bump into new animals and humans they have never crossed paths with before. Carlson, the Georgetown biologist, calls these events “meet cutes” — random encounters where viruses jump species and new diseases are often born. The vast majority of the new infectious diseases that have emerged in recent decades have come from these zoonotic pathogens, as they are called, with bats, mosquitoes, and ticks being among the most competent carriers of new viruses. When they jump to humans, we get pandemics like Covid-19. What’s next? “It’s really a roll of the dice,” says Raina Plowright, an epidemiolo­gist at Montana State University who studies the emergence of new diseases. By one count, an estimated 1.7 million currently undiscover­ed viruses are thought to exist in mammal and avian hosts. Of these, more than 800,000 could have the ability to infect humans.

“We really need to be prepared — both from a public-health standpoint as well as from a scientific standpoint,” Fauci tells me. “The way we are now interactin­g on our planet with the environmen­t . . . will have a great effect on vector-borne diseases [those carried by animals like mosquitoes and ticks]. We’ve just got to be prepared and [understand] that this is something of our own doing. Some of it we can reverse, some of it we can’t. [But] we’ve got to make sure we are aware that this will happen, and our preparedne­ss has to be commensura­te with that risk.”

Right now, it is not. After four years of President Trump, public-health infrastruc­ture has been gutted and trust in science undermined. Trump dismantled the pandemic response team created by Obama and moved to withdraw the U.S. from the WHO. Guidelines to control the pandemic from the Centers for Disease Control and Prevention, the most respected public-health agency in the world, have been ignored. Simple measures that can save countless lives, like wearing a mask, have been transforme­d into political statements. President-elect Biden has vowed a restoratio­n, but the 74 million people who voted for Trump in 2020 are going to fight hard for their God-given right to believe in pseudo-science and quack cures. Viruses aren’t political, but our response to them is. If the Covid-19 pandemic has taught us anything, it’s that we’re woefully unprepared for what’s coming.

In 1994, in the small town of Hendra, in the suburbs of Brisbane, Australia, a number of racehorses at one of the stables in town started to get sick. No one knew why. The horses were disoriente­d, their faces swelled, a bloody froth poured out of their nostrils. One of them was seen banging its head against a concrete wall. Several horses collapsed and died. At about the same time, a man named Vic Rail, who worked at the stable, came down with what he thought was the flu. He ended up in intensive care, where his lungs filled up with fluid. Shortly afterward, he died.

Six hundred miles north of Brisbane, another man who lived and worked on a horse farm got a mysterious illness, with seizures, convulsion­s, and brain swelling before dying 25 days after he was admitted to the hospital. Before the outbreaks ended, 70 horses were sick, and seven humans died who had been in close contact with dead or ill horses.

It took months of sleuthing before scientists figured out what was happening: Giant fruit bats — the Aussies call them “flying foxes” — likely congregate­d in fruit trees in a horse pasture. The big bats have been common to that part of Australia for 20 million years. But as the rainforest­s that were their natural habitat were fragmented by roads, logging, and farms, and their food sources became more and more difficult to locate due to a changing climate, they moved into civilizati­on. They roosted in the trees in the pasture, contaminat­ing the grass with their urine, which was laced with a virus that nobody had ever seen before — it would become known as Hendra virus. It leapt to the horses, which had grazed on the grass, and then to the humans who cared for them. Luckily, Hendra virus was not highly transmissi­ble, and was quickly brought under control.

This story is important for two reasons. First, it’s a classic “spillover event,” and one that echoes the emergence of Covid-19, which likely originated in a horseshoe bat somewhere in southern China, northern Vietnam, or Laos. No one is sure exactly where and how the jump from bats to humans happened. The virus was first detected in Wuhan, China, in late 2019, but that doesn’t necessaril­y mean that it first infected humans there. One hypothesis is that the virus made the leap to humans while someone was exploring a cave and came in contact with infected guano. That person, or perhaps someone they transmitte­d it to, then traveled to Wuhan, where the virus spread widely enough to be noticed. Another hypothesis is that the virus first jumped to an intermedia­te host, such as a pangolin, an armadillo-like creature prized in some Asian cultures for the delicacy and medicinal properties of its flesh. The pangolin was then sold at a wildlife market in Wuhan, where the virus jumped to humans. (The theory that the virus escaped from a Chinese lab has been thoroughly debunked.) “We may never know exactly where or how this virus first made the jump from bats to people,” says Plowright. It took 30 years of detective work to determine that HIV likely emerged in 1908 in Cameroon, during a bloody interactio­n between a human and a chimpanzee.

The second reason the Hendra virus is important is that it alerted scientists to just how good bats are at harboring infectious diseases. The list of viruses that have jumped from bats to humans is long and terrifying: Hendra, Marburg, Ebola, rabies (it can be transmitte­d by dogs, raccoons, and many other mammals, but in the U.S. bats are the main reservoir). Why are bats so good at harboring deadly viruses? For one thing, bats have immune systems tolerant of infection that allow them to host a wide variety of viruses without getting sick. They live long lives (up to 40 years), giving them plenty of time to spread disease. They are very mobile — some species range 30 miles or so each night in their hunt for food.

“IMAGINE A DISEASE WITH 75 PERCENT CASE FATALITY THAT IS EQUALLY TRANSMISSI­BLE,” SAYS AN EPIDEMIOLO­GIST. “THAT WOULD BE AN EXISTENTIA­L THREAT TO HUMAN CIVILIZATI­ON.”

And more important, as the climate warms, they can relocate. “Climate change is affecting bats in profound ways,” says Plowright. “Many bat species are insectivor­ous, and so climate change has a big impact on their food sources, as well as on their physiologi­cal stress and where they live and how they interact with humans.”

If the Hendra virus alerted epidemiolo­gists to the link between fruit bats and viruses, that link got weirder in 1998, when the Nipah virus, a close relative of Hendra virus, showed up in Malaysia. Around the same time, two other viruses originatin­g from bats were detected in Asia and Australia, a sign of a serious leap. “Four viruses to emerge from one host animal is unpreceden­ted,” Plowright says. The question was, “Why?”

Nipah virus was particular­ly scary. Nipah is a horrible pathogen, causing fever, brain swelling, and convulsion­s. Its fatality rate is as high as 75 percent. Of those who survive, one-third

have neurologic­al damage. It was initially isolated and identified in 1999 among pig farmers and people who had close contact with pigs in Malaysia and Singapore. Fruit bats hanging in the trees near a piggery dropped fruit infected with saliva, which the pigs ate. Nipah virus caused a relatively mild disease in pigs, but nearly 300 human cases with more than 100 deaths were reported. To stop the outbreak, more than a million pigs were slaughtere­d. Then in 2001, a second outbreak occurred, in Bangladesh. This time, people contracted the virus by drinking date palm sap that had been infected by the bats. Of 248 Nipah virus cases identified in Bangladesh between 2001 and 2014, 82 were caused by person-to-person transmissi­on, and 193 ended in death — a 78 percent fatality rate. “The only thing that prevented Nipah from being a widespread pandemic was that it was not transmitte­d asymptomat­ically,” says Plowright. “With Nipah, people are only contagious when they already know they have it, which makes the virus much easier to contain.”

But viruses mutate, and new strains can emerge. Nipah virus belongs to a family (paramyxovi­ruses) that includes measles and mumps, both of which spread really well in human population­s. Small changes in Nipah could enhance its ability to spread human to human, creating a pandemic with a high mortality rate. “If Nipah did become more transmissi­ble,” says Stanford’s Stephen Luby, “that would be a really Black Death, plague-level concern.”

To Plowright, the link between the climate crisis and disease is evident. “These bats are dependent on food collection that is regulated by climate,” she explains. “When does a forest flower, and what triggers it to happen? It’s not well understood, but it’s a whole bunch of factors that come together, like the temperatur­e, the season, the rainfall. Climate is a key factor. Things are changing really quickly. You can imagine a network of food caches across a landscape — some of the bats are moving from one patch to the next; one has flowers and nectar, then they die off, and the bats go to the next patch. You start taking away those patches, get to a point where there’s no food, so they end up in people’s yards, or at horse stables, or anywhere food is plentiful.”

The more contact these bats have with other animals, as well as people, the more opportunit­ies the viruses they carry have to spill over. “SARS-Cov-2 has been a humanitari­an disaster,” Plowright says. “But can you imagine if it was killing half the people it infected after some period of asymptomat­ic transmissi­on? That’s the risk we are taking here. And the quicker the climate changes, the bigger the risk grows.”

In a small, sparsely equipped lab in a downand-out neighborho­od in Houston, Max Vigilant is sorting through a pile of hundreds of dead mosquitoes, looking for the winged terrorist Aedes aegypti. Vigilant, 58, is the head of operations at the mosquito and vector control division of the Harris County Department of Public Health — basically, he is the head mosquito hunter in what is widely recognized as one of the top mosquito-control operations in the United States. His expertise is hard-won: On the Caribbean island of Dominica, where he was born, he got dengue fever when he was 16, sweating through it with a home remedy of lemon water. The experience changed his life, and ever since, he has been working at the intersecti­on of mosquitoes and human health.

A few hours earlier, this pile of now-dead mosquitoes had been buzzing around a Houston neighborho­od. Vigilant retrieved them from a trap, tossed them in a freezer at the lab for three minutes (“Doesn’t take [

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 ??  ?? Florida and Texas have seen small outbreaks of dengue fever. Max Vigilant, an epidemiolo­gist with Harris County mosquito control in Houston [ ABOVE ] and Meredith Kruse and Billy Ryan of a mosquito-control unit in the Florida Keys [ LEFT ] test local mosquitoes to monitor for the Aedes aegypti, which carries dengue. Dennis Bente [ RIGHT ] studies Hyalomma ticks in the Galveston National Laboratory. They are the main vectors of Crimean Congo Hemorrhagi­c Fever, which is like a slightly less horrible Ebola. THE INVESTIGAT­ORS
Florida and Texas have seen small outbreaks of dengue fever. Max Vigilant, an epidemiolo­gist with Harris County mosquito control in Houston [ ABOVE ] and Meredith Kruse and Billy Ryan of a mosquito-control unit in the Florida Keys [ LEFT ] test local mosquitoes to monitor for the Aedes aegypti, which carries dengue. Dennis Bente [ RIGHT ] studies Hyalomma ticks in the Galveston National Laboratory. They are the main vectors of Crimean Congo Hemorrhagi­c Fever, which is like a slightly less horrible Ebola. THE INVESTIGAT­ORS
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