This book tells both sides of the story of germs: that they are critically important for our health and that the dangers of emerging pathogens continue to wreak havoc in our bodies and around the world. Infectious diseases physician Phillip Peterson surveys how our understanding of viruses has changed throughout history, from early plagues and pandemics to more recent outbreaks like HIV/AIDS, Ebola, and the Zika virus. He also also examines contemporary issues such as the importance of vaccinations in the face of the growing anti-vaxxer movement, as well as the rise of cutting-edge health treatments like fecal transplants.

Introduction: How tiny creatures make a huge impact -- Intimate friends. The tree of life ; It's a microbial world ; The human microbiome ; Departments of bodily defense ; It's all connected: the health of humans, animals, and our planet -- Mortal enemies. What has plagued us? ; Killer viruses ; The buzz on mosquito-borne infections ; Microbes in flight: birds and bats ; Don't breathe this air ; Microbes in the woods ; What's in the beef? ; Gut reactions ; When beauty isn't skin deep ; The perils of antibiotic misuse -- Germs in the future. The straight poop on fecal transplants ; Healing with friendly bacteria and fungi ; Healing with friendly viruses ; The future of vaccines ; Microbes and the sixty extinction ; Science, ignorance, and mystery -- Appendix: Landmark discoveries and notable germs.