Emily Monosson (W. W. Norton)
EVEN if you haven鈥檛 seen the TV show The Last of Us, by now you will probably have heard someone describe its terrifying depiction of a world overrun by a brain-eating fungus 鈥� a Cordyceps 鈥� that evolves to infect humans due to warming temperatures. The show has done for fungal pathogens what Jaws did for shark attacks: it focused attention on an overlooked threat and people freaked out.
Unlike giant, vicious sharks, however, fungal pathogens are common. In fact, as toxicologist and science writer explains in Blight: Fungi and the coming pandemic, deadly fungal outbreaks have actually occurred across the tree of life. 鈥淐ollectively, infectious fungi and fungus-like pathogens are the most devastating disease agents on the planet,鈥� she writes.
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That isn鈥檛 to say all fungi are bad, of course. Most of the roughly 6 million species that surround us are not only harmless, but are essential parts of ecosystems. Some fungi form mutualistic relationships with plant roots, improving their ability to absorb nutrients from soil, for instance. Without fungi to decompose dead organic matter, Monosson writes, 鈥渢he world would be piled high with the deceased and would be virtually uninhabitable鈥�.
As for the fungi that aren鈥檛 so friendly, Monosson focuses on several of the worst fungal epidemics and the researchers studying them. Frogs all over the world have been killed by the skin-eating chytrid fungus Batrachochytrium dendrobatidis, or Bd, which is probably spread through the global animal trade.
Billions of American chestnut trees were killed by a fungus that travelled to North America aboard a ship. And a fungal disease called white nose syndrome, which probably spread to North America from Europe via people, has killed millions of bats in the past decade.
Like most mammals (apart from bat species that cool down during hibernation), human temperatures are too high to make us susceptible to most fungal pathogens. There has never been a fungal pandemic in humans, but our luck may be running out, writes Monosson.
A fungicide-resistant fungus called Candida auris is an emerging threat for those with weakened immune systems. (Other human fungal pathogens can be a side effect of antibiotics altering the microbiome.) Some researchers argue the emergence of C. auris in humans may be down to adaptation to warmer temperatures due to climate change. It is no brain-eater, as in The Last of Us, but it is real.
Fungal disease doesn鈥檛 have to infect humans directly to have dire consequences. Take Costa Rica. Monosson describes how a would wreck its economy and social fabric. Wheat, soya, corn, rice and other important crops also face threats from fungi.
Monosson outlines the elaborate strategies fungal pathogens use to infect and spread. But humans are implicated because we 鈥渢ravel, plant massive monocrops, trade plants and animals鈥�. We haven鈥檛 simply opened Pandora鈥檚 box, she says, we have swung it around and shaken out the contents.
Here, Monosson makes a vigorous defence of attending to the interconnections between humans and species of all kinds when it comes to preventing pandemics. She also explains how researchers, farmers and governments are fighting back against fungal pathogens, from monitoring for new threats to developing new fungicides and breeding or engineering trees that can resist fungal invaders.
For all its devastation, Blight isn鈥檛 the most engrossing book. It lacks narrative and is repetitive at points. But if you find fungi fascinating, and want to know more about the nasty ones, it is well worth reading. Fungal reality may prove scarier than fiction.
