In writing about the natural world, noticing is not merely good reporting, it is an ethical act. As Martins careens through the mind-boggling diversity of parasites, he delivers a seemingly endless array of eye-popping facts. And, unsurprisingly, in many instances the prevalence of preventable diseases caused by parasites maps onto the legacies of inequity left by colonialism. Nonetheless, for Martins the question of whether we can, or even should, try to eliminate parasites is complex. Studies suggest that a lack of exposure to microbes and parasites in childhood increases our susceptibility to allergic and autoimmune diseases.