We’re just a big, hairy afterthought to life on earth. This world belongs to microbes; we just live on it, and not always comfortably. If the viral particles (which are just a fraction of all microbes) on Earth− a staggering 1 x 1031− were laid end to end, they would stretch 100 million light years away. Yet while we know that there are tons of microbes on earth, we don’t know how much diversity there is among their ranks. The total number of microbial species is unclear and the estimates vary widely, ranging from a low of around 120,000 to tens of millions or more.3 Regardless of the exact number, it is obvious that−to date− we have only scratched the surface of microbial diversity.
Unfortunately, in this case, what we don’t know can hurt us. While the vast majority of microbes are benign, there are plenty that can do us ill, literally. There are currently about 1,400 known human pathogens (microbes that cause disease, including viruses, bacteria, fungi, protozoa, and helminthes). While that’s far less than 1% of the microbial species on the planet, they do plenty of damage.3 Searching for new microbes promises not only to increase our knowledge of life on earth, it may also be a chance to safeguard human life.
In recent years, we have heard a lot about zoonoses (diseases that spillover from animals to humans), and with good reason (see my post on the issue). Of the 335 novel (new) infectious disease that were reported from 1940-2004, 60.3% came from animals, and most of those came from wildlife.2 Although the exact origins of some pathogens are hard to trace, it’s clear that many of the most lethal diseases afflicting humans (e.g. SARS, Ebola, etc.) have come from our wild or domesticated brethren. With increasing agricultural intensification and greater and greater encroachment into natural areas, there is every reason to expect the future to hold more of the same.
While that is a terrifying fact, it shouldn’t be paralyzing. So why aren’t we acting against these microbial horrors now, while we have the chance? Well there’s a rub: normally we have to wait until someone gets sick to identify a pathogen or even recognize the start of an epidemic5, especially of a new disease, and by then it’s (by definition) too late.
That’s all beginning to change. Over the past two decades, several groups of scientists have started to turn the tables on microbial pathogens, especially viruses. Instead of waiting for them to find us, these researchers are setting out to find them.
On the hunt
Perhaps the most prominent virus hunter is Dr. Nathan Wolfe, a visiting professor at Stanford University who has dedicated his career to seeking out pathogens around the globe.5 He works with a large team; in 2007, Wolfe founded the Global Virus Forecasting Initiative, a nonprofit research institute, and in 2008, he founded Metabiota, Inc., a for-profit sister company that provides disease surveillance, forecasting, and epidemic data.1,5 Wolfe and his collaborators work in more than 20 countries, focusing on Central Africa and South Asia, regions where large groups of people live cheek by jowl with the animals they depend on, either for bushmeat (tropical wild game, including monkeys, gorillas, and chimpanzees, among many other species) or for agriculture.4,5
The group has set up listening posts across their study regions where they survey for pathogens, regularly sampling animals and humans alike. Possibly more importantly, they educate locals about the risks of exposing themselves to the bodily fluids of animals.4 What they have found in the course of their work is both surprising and disturbing. Along with discovering several new viral species, they have uncovered much more viral spillover between animals and humans than anyone expected. Their results from Central Africa are particularly alarming: 1% of hunters sampled in Cameroon had simian foamy virus (SFV), a retrovirus that is a relative of HIV.5 Although thankfully SFV doesn’t cause illness in those infected, it’s presence shows that the barrier between humans and animals is more permeable than we thought.
These findings have made a significant impact, inspiring greater surveillance efforts and raising awareness. But despite the best efforts and frightening discoveries of Wolfe and his team, we will all remain at risk while we allow large chunks of humanity to suffer, impoverished and ignored. In Central Africa, bushmeat is a principal protein source; the region consumes at least 2 million tons per year. This may seem unthinkable or willfully self-destructive, given what we now know may be lurking in the meat, but although many residents of the region are no longer ignorant of the risks, they still have no other options. The alternative is often hunger or malnutrition for themselves and their families.4 So while the risks of illness are potentially enormous, they aren’t as immediate or as certain as an empty stomach.
Make no mistake: we may die of disease, but it’s poverty that’s killing us.
- Hope, B. Virus Hunter Metabiota Finds Niche in Epidemic Research. The Wall Street Journal Online. 20 May 2015. Web. 23 October 2015.
- Langreth, R. Finding the Next Epidemic Before It Kills. Forbes.com. 6 November 2009. Web. 23 October 2015.
- Editorial Staff. 2001. Microbiology by numbers. Nature Reviews, 9: 628.
- Specter, M. The Doomsday Strain. The New Yorker Online. 20 December 2010. Web. 23 October 2015.
- Wolfe, A. Nathan Wolfe: On the Hunt for New Viruses. The Wall Street Journal Online. 12 December 2014. Web. 23 October 2015.
Image source: NIAID, https://commons.wikimedia.org/wiki/File:Ebola_Virus_Particles_(4).jpg
For more on Dr. Wolfe’s work, check out his TED talk.