Marcus Lavergne/Nevada Sagebrush
Science writer, David Quammen, lectures inside the Davidson Math and Science Center on Thursday, Feb. 4. Quammen explains that humans, a rapidly growing population, are at high risk of contracting animal-to-human viruses.
By Marcus Lavergne
Viruses discovered decades ago have come back to haunt humanity, causing some of the world’s most vicious and mysterious diseases. In recent cases, such as the epidemic caused by the Ebola virus’s explosion throughout West Africa, there came a lethality that disrupted the lives of millions, even separating families from their loved ones.
More than 25,000 people contracted Ebola, and it took the lives of about 11,000, making it the largest outbreak of the disease in history. The World Health Organization officially deemed it an outbreak in 2014, and although countries like Liberia and Sierra Leone are now out of the quarantine stage, scientists and medical professionals have yet to create a vaccine for the virus, though at least two are currently in testing.
Now that Ebola has exited the spotlight, another virus has entered affecting pregnant women and their fetuses. Zika virus now plagues South America in countries like Brazil and Colombia. On Feb. 1 the WHO declared it a global public health emergency, putting the world on high alert, after thousands of confirmed cases came to light.
After the virus initially appeared in Brazil last May, more reports released in the fall uncovered a spike in the number of infants suffering from microcephaly. Studies show that the virus has a link to the birth defect, which is characterized by babies born with undersized or deformed heads, which is in turn associated with improper brain development.
Zika moves fast and far in the bodies of its vector, the Aedes mosquito. According to the Centers for Disease Control and Prevention, the virus is being actively transmitted from person to person in over 20 countries across the Americas.
Zoonotic viruses like Zika, Ebola, MERS, Influenza and HIV/AIDS have all transferred through animals into humans at some point in time. Their prominence in human populations highlights weaknesses such as the world’s growing population and a lack of preventative treatment and cures.
David Quammen is a science writer who has been addressing these issues. He has published 15 books on science, nature and traveling. He focuses on topics such as the hyper interaction between humans and areas like tropical rain forests where unknown viruses and diseases lie dormant.
Last Thursday, he came to the University of Nevada, Reno, where he lectured on some of those viruses and the potential future of humankind. For Quammen, who’s had science articles published in periodicals like National Geographic, Rolling Stone and the New York Times Book Review, the unknown presents a chance to travel to interesting places and meet interesting people.
“I like to go to wild places,” Quammen said. “Some guy’s going to walk across the Congo in a pair of Teva sandals for 2,000 miles studying the presence of gorillas and forest elephants. ‘Do you want to go with them?’ ‘Duh, yeah.’ So I go, and I do that assignment.”
Zoonotic diseases make up 60 percent of all known human diseases according to the CDC. Out of all of the diseases man has discovered, it turns out that 13 of them kill over 2 million people each year. During Quammen’s lecture, “Ebola & Beyond: Scary Viruses in a Globalized World,” he emphasized that this lack of resilience to zoonoses serves as an important reminder.
“It reminds us of the connectedness between humans and animals,” Quammen said. “[It’s] the Darwinian truth — we humans are animals, part of nature, not separate from it or above it.”
It comes down to three factors that Quammen equates with the spillover that humans are seeing, or the salient interaction between humanity and the reservoir hosts that carry dormant and active viruses. According to him, those factors are disruption, connectivity and the biodiversity of viruses.
By becoming so intertwined with nature and also disrupting the natural flow of things, humans have opened up a gateway to that viral biodiversity. Industrialization, experimentation, exploration and the like each help open up a path for transmission of viruses, and that could mean the evolution and survival of new diseases.
“Any virus that has lived for a millennia in an animal that is now becoming an endangered species makes a really good career move when it transfers its attention to humans,” Quammen said.
Quammen uses the chimpanzee and the AIDS virus as an example. Chimps are being pushed past the point of endangerment, but that hasn’t stopped AIDS from taking more than 35 million human lives between 1908 and 2015. When a virus moves into a human, its chances for evolutionary success increase. It should be noted, however, that there remains some debate over the link between AIDS and chimpanzees.
According to Quammen, the next great pandemic, which could be upon humankind in the form of the Zika virus, could take millions of lives. But it turns out that humans might’ve been asking for this to happen. Quammen calls human beings an outbreak population, comparing us to tent caterpillars.
The tent caterpillars grow exponentially for a time, devastating forest trees by devouring their leaves. This doesn’t last for long though, and eventually that population goes through a crash or significant and rapid drop in population size. According to Quammen, a big reason for that drop is disease — a highly prevalent part of human life.
“With viruses, you can’t treat them with antibiotics,” Quammen said. “There are drugs called antivirals, they’re helpful in some cases, but they aren’t magic bullets. You can vaccinate, if you can find a vaccine, but it takes a lot of time and a lot of money.”
During Quammen’s travels, he discovered hope in the form of a term known as “heterogeneity of behavior.” Human beings can avoid tent caterpillar population crashes through learning, adapting and using “intelligent steps to change ourselves.” He believes that epidemics like the Ebola outbreak in West Africa have to be treated as a world problem.
Humanity is ultimately bound to decline in population size due to several reasons including scarce resources, space and newly discovered viruses waiting to evolve, but that doesn’t have to be a rapid, disastrous event. It can be a “gentle decline,” where humans can thrive, and not just survive.
Marcus Lavergne can be reached at mlavergne@sagebrush.unr.edu and on Twitter @mlavergne21.