This bug could save your life

been tilting at microbes for too long,” Yong writes, “and created a world that’s hostile to the ones we need.” It turns out that opening the window of a hospital room is beneficial for the patient (as Florence Nightingale long ago suspected), because it enables pathogenic bacteria to leave and helpful ones to enter. Architects are studying how to build “good” microbes into hospital walls.

One’s eyes do occasionally glaze over in the parade of bugs, but in the main Yong’s book is vividly enjoyable. He visits scientists in their labs, and they say funny things. (“You can’t go wrong with mucus, because mucus is cool.”) He has a favourite bacterium, Wolbachia, which hides in insects and other arthropods. It’s also an example of how the new microbial science might save lives. One team is deliberately infecting mosquitoes with Wolbachia, because it makes them immune to the viruses they usually pass on to humans. If you release enough Wolbachia-laden mosquitoes into the wild, you might wipe out dengue fever or even malaria.

Managing the microbial systems in humans themselves, meanwhile, is a new frontier in medicine. There has already been a lot of hype about faecal transplants, in which “doctors take stool from a donor and install it in a patient’s guts”.

This, it turns out, can quickly cure chronic diarrhoea caused by the C difficile bacterium, but the suggested benefits for other disorders, such as obesity and even autism, are unproven. In the future, however, scientists may be able to design a microbial ecosystem for each patient from scratch and pack it into a pill, to treat a wider variety of illnesses. Medicine, Yong suggests, may become more like ecology: restoring the ecosystems of the human body to harmony.

One scientist gives out an Overselling the Microbiome Award to colleagues or journalists he feels are exaggerating the importance of all this. Yong hopes he doesn’t deserve one, and in the main I agree. His book may contain many disgusting stories from the frontier of microscopic science, but it is strangely comforting.

We all travel through a cushioning cloud of our own bacteria. So, as Yong writes prettily: “A polar bear trundling solo through the Arctic, with nothing but ice in all directions, is completely surrounded.” Even when you think you’re alone, you aren’t really.

Steven Poole on how he learnt to stop worrying and love the microbe