Speaking of which, what counts as dysbiosis? How can you tell if an ecosystem is in disarray? A bloom of C. difficile that causes unstoppable diarrhoea is a clear problem, but most other communities are not so easily classified. Is a gut without B. infantis in a state of dysbiosis? If your microbiome has fewer species than a hunter-gatherer’s, is it dysbiotic? The term is great at conveying the ecological nature of disease but it has also become microbiology’s version of art or pornography: hard to define, but you know it when you see it. And many scientists seem unhelpfully quick to label any
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