Virus Hunters: Searching for Microbes in the Wild

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.

Virus hunters

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.

virus hunters
Mugshot.

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.

References

  1. Hope, B. Virus Hunter Metabiota Finds Niche in Epidemic Research. The Wall Street Journal Online. 20 May 2015. Web. 23 October 2015.
  1. Langreth, R. Finding the Next Epidemic Before It Kills. Forbes.com. 6 November 2009. Web. 23 October 2015.
  1. Editorial Staff. 2001. Microbiology by numbers. Nature Reviews, 9: 628.
  2. Specter, M. The Doomsday Strain. The New Yorker Online. 20 December 2010. Web. 23 October 2015.
  1. 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.

Scurvy: Apples and Oranges

Aliases: scurvy, amalati de la boccha (curse of the mouth), Cheadle disease, Barlow disease

Scurvy is one of the oldest diseases in human history. It was first recorded in an Egyptian medical scroll in 1550 BCE. (The suggested treatment? Vegetables. Nailed it!). It even got a mention by Hippocrates, the originator of the Hippocratic oath, who wrote the first formal description of the disease. Yet despite our long association with scurvy, it took until the 20th century and the discovery of vitamin C for a definitive cure to be found.1 In our ignorance about human nutrition we circled the answer for centuries and kept passing the right conclusion by like ships in the night (pun intended).

Scurvy is the bane of both the bold and the disenfranchised, dogging explorers and anyone else in situations of deprivation. Scurvy plagued the crews of the 15th and 16th century explorers; between 1500 to 1800 CE, scurvy killed more sailors than all other diseases and disasters combined.3 The disease was so prevalent among seamen that some suggested that the illness was caused by the sea itself. The theory went on to suggest that a simple return to land should provide a cure.4 (To our ancestor’s credit, that idea was quickly dismissed, especially when outbreaks of the disease started to occur regularly on land.). Scurvy flourished wherever fresh vegetables were scarce, afflicting far-flung outposts, including gold miners in California and the polar expeditions of the 19th century. It was also common in areas of conflict and prisons, heaping injury upon injury, as disease so often does.1

The threat of scurvy did not escape the attention of the very explorers it afflicted. Captain James Cook was particularly famous for his study of scurvy. Through careful observation he found two ways to successfully combat scurvy on his long sea voyages (among other less accurate proposals, like beer): procuring fresh food whenever possible, and carrying and using preserved foodstuffs thought to prevent scurvy, like sauerkraut and portable broth (a soup prepared from cattle offal and vegetables that was evaporated into hard cakes). His hard work was rewarded when he was awarded the Sir Godfrey Copley’s medal by the Royal Society of London (awarded annually to the “most useful and most successful experimental inquiry”) for his experimentation on the treatment of scurvy during his 1772-1775 voyage in the South Pacific.4

But despite the mounting evidence for the medicinal effects of fresh fruit and vegetables, doubts remained. This is due in part to the complexity of the problem and the specificity of the solution. Vitamin C deficiency results in a huge array of conditions, and many appear unrelated.3 And although fruit and vegetables alleviate scurvy, it’s really apples and oranges. Not all sources of vitamin C are equal; there is a wide range of vitamin C concentrations among fresh foods. This kept us dancing around the truth even when it was staring us in the face. The unfortunate scientist James Lind even managed to show that oranges successfully treated scurvy in 1753. But because he could not pinpoint the cause of the disease (which wasn’t demonstrated until the 1930s) his findings were not widely accepted, resulting in nearly two more centuries of mistreatment.1

scurvy
What’s cooking, Captain? See (C?) what I did there?

Cause: Scurvy is the result of severe vitamin C deficiency. Really, really severe. For clinical symptoms to develop, the body’s store of vitamin C (an essential nutrient for collagen and bone formation, among many other things) has to diminish from 1500mg (a normal body store) to 350mg or less. That requires the total elimination of vitamin C from your diet for 60-90 days.3 Although scurvy is most common when fruit and vegetables are scarce, it can also result from malnutrition, which can be caused by a whole suite of conditions, including malabsorption issues, eating disorders, and allergies.2

Consequence: Common symptoms of scurvy include irritability, bone pain, limping, rash, and spongy, bleeding gingiva (the soft mouth tissue surrounding the teeth). More extreme symptoms include seizures, heart failure, bone fractures, and pseudoparalysis. Left untreated, scurvy is often fatal.3

Cure: Despite the seriousness of the condition, scurvy is shockingly treatable and the cure is simple. Treatment involves flooding the body with the maximum dose of vitamin C. The body’s stores can be replenished within just a few days, and patients generally improve within 24 hours. Their pain usually decreases over 2-4 days and mouth lesions heal in 2-3 weeks.3 Full recovery takes just 3 months2 and there is usually little to no permanent damage after treatment. So, while an apple (about 8mg of vitamin C) a day can keep the doctor away, an orange (60mg of vitamin C) is better.3

References

  1. Magiorkinis, E., A. Beloukas, and A. Diamantis. 2011. Scurvy: past, present and future. European Journal of Internal Medicine, 22:147-152.
  1. Levavasseur, M., C. Becquart, E. Pape, M. Pigeyre, J. Rosseaux, D. Staumont-Sallé, and E. Delaporte. 2015. Severe scurvy: an underestimated disease. European Journal of Clinical Nutrition, 69: 1076-1077.
  1. Popovich, D., A. McAlhany, A.O. Adewumi, and M. McKim Barnes. 2009. Scurvy: forgotten, but definitely not gone. Journal of Pediatric Health Care, 23: 405-416.
  1. Stubbs, B. 2003. Captain Cook’s beer: the antiscorbutic use of malt and beer in late 18th century sea voyages. Asia Pacific Journal of Clinical Nutrition, 12:129-137.

Image source: Creative Commons, https://en.wikipedia.org/wiki/James_Cook