Disease-causing microbes were discussed by microbiologist Jason Tetro, a visiting scientist at the University of Guelph, with the Globe and Mail Jan. 12. Tetro is the author of The Germ Files: The Surprising Ways Microbes Can Improve Your Health and Life (And How to Protect Yourself from the Bad Ones). Tetro, a U of G graduate, said microbes can help strengthen our immune systems. He said the microbes we encounter in urban environments are generally neither harmful nor helpful given their low diversity.