"Origin stories for today's viruses often start with animals; HIV in humans begins with a chimpanzee, or our COVID-19 pandemic with possible transmission from bats. But it often works the other way around-humans have caused diseases in other animals countless times throughout history. In this eye-opening and timely book, science journalist Liz Kalaugher explores the invisible crosscurrents between humans, other animals, and disease. Offering readers a front-row seat to today's research on wildlife diseases, each chapter focuses on a single example and incorporates interviews with scientists and other experts. As the book unfolds, we see how humans have spread diseases directly to other animals, and indirectly by altering ecosystems, transporting life around the globe, and changing the planet's climate. In one chapter, Kalaugher examines the role of high-density poultry farms in creating virulent new forms of bird flu that spilled back into the wild and have spread around the world, potentially putting humans at risk of another pandemic. In another chapter, we learn an infectious cancer-canine transmissible venereal tumor-may have wiped out North America's very first dogs, after Europeans' domesticated canid companions introduced the disease. Later, Kalaugher offers evidence that rising global temperatures will further spread diseases like West Nile, which already affects not only crows and humans, but also horses, gray wolves, skunks, squirrels, little brown bats, and alligators. West Nile has trouble spreading at the cooler temperatures (for now) where seventy percent of the US population lives. But as global temperatures increase, so does risk. All these stories make clear that a better understanding of wildlife diseases-and humans' roles in spreading them-is essential for a better and healthier future for all animals, including people"-- Provided by publisher.