Wednesday, September 7, 2016
The next great pandemic: What will it look like and where will it come from?
This was originally published on Global Health TV on August 23, 2016.
A few years ago, in a survey by epidemiologist Larry Brilliant, 90 percent of epidemiologists said that a pandemic that will sicken 1 billion, kill up to 165 million and trigger a global recession that could cost up to $3 billion would come in the next two generations. Currently, we’re living through three pandemics — HIV, Zika and cholera. What will the next pandemic look like and where will it come from?
Those are some of the questions science journalist Sonia Shah attempted to answer in an event marking the centennial of the Johns Hopkins University’s Bloomberg School of Public Health and in her book “Pandemic: Tracking Contagions from Cholera to Ebola and Beyond,” published earlier this year. The book should be required reading for anyone interested in the future of global health.
Shah spent six years trying to figure out how microbes turn into pandemic-causing pathogens. She looked at the history of pandemics, particularly cholera because it’s one of our most efficient pandemic-causing pathogens. She went to places where new pathogens are emerging to try to figure out what are the political and social drivers that push these microbes into human populations.
She found that one of the major drivers is wildlife. A disproportionate number of human pathogens come from other primates, who’ve given us 20 percent of our most burdensome pathogens (including HIV and malaria).
“About 60% of the new pathogens are emerging in animals,” she said. “Over 70% of those come out of wild animals. From bats, we’ve gotten Ebola, Nipah, SARS and Marburg, from birds we’ve gotten Avian influenza and West Nile virus, from rodents we’ve gotten Monkey Pox and Lyme Disease, from monkeys we’ve gotten malaria and HIV and probably Zika.”
The expansion of the human population is destroying wildlife habitat and this results in the remaining wildlife crowding in ever closer to humans.
“We’re creating more and more interfaces between humans and wildlife that allows for novel, more intimate kinds of contact in which the microbes that live in their bodies, can spill over into our bodies,” she said.
And animals, as well as humans, are crowding together. Shah says we have more animals under domestication today than in the last 10,000 years of domestication until 1960 combined. And an increasing proportion of these animals are living on factory farms, which she calls “the animal equivalent of slums, where you have hundreds of thousands of animals crowded really closely together where they’re breathing on each other, touching each other and being exposed to each other’s wastes. This is another opportunity new pathogens are exploiting.”
This new sanitary crisis is in addition to our old sanitary crisis in which 2.6 billion people don’t have access to any modern sanitation. In this new crisis, livestock produces 7 billion tons of excreta every year, which is far more than our crop lands can absorb. So we have giant open cesspools of untreated animal waste, which seeps into the environment.
And we’re spreading these pathogens around more efficiently than ever with extensive flight networks. Consequently, Shah says, even when one of these pathogens emerges in a place where there’s not a lot of susceptible people, it can quickly travel to a place where there are, to such an extent that we can predict where a pathogen will strike next by measuring the flights between infected and uninfected cities.
Since a lot of these pathogens are coming out of animals and driven through human populations by social and political factors, you would think that the best way to tackle this problem would be through an interdisciplinary approach. “Get the veterinarians, wildlife biologists, ecologists, engineers, anthropologists, political scientists, economists and bio-medical specialists together to look at the entire process,” she said. “But of course, that’s not what we do. We approach infectious outbreaks as solely a bio-medical phenomenon, reducing it to its smallest components, and then striking it down with surgical precision.”
Shah pointed out that Brilliant didn’t have a crystal ball. He was merely a warning of what will happen if we don’t change. She believes there is a lot that we can do with early detection, as this article points out. We don’t have to wait for the vaccines and drugs.
Ultimately, she said, we have to reduce the conditions that allow pandemics to occur, things like restoring wild habitats, so the microbes in animals stay in animals and do not cross over into humans. We have to protect the health of the most vulnerable among us, people who live in slums and animals in factory farms.
“We need to reimagine our relationship to the microbial world,” she said. “There is no ‘us’ and ‘them’ anymore. This is their planet, and they were here first. And they’re a lot better at living here than we are. We have to recognize that our health is connected to the health of our societies but also the health of our animals, our wildlife and our ecosystems.”
So what will the next pandemic look like? Shah says we don’t have a great track record predicting pandemics (no one predicted Zika) but sees two scenarios as the most likely:
1) A novel form of influenza, because influenzas are so efficient at spreading that even a slight increase in mortality from a virus would result in a huge number of deaths; or
2) An antibiotic-resistant bacteria, which poses a huge threat to public health because even a common injury like a scratch can become life threatening.
Shah says there is one thing that lets her sleep. “Look at it from the pathogen’s point of view. They need to transmit from one person to another but if they kill you too fast, they’re not going to be able to transmit very well. That helps me sleep.”