CharlesKennyThe Plague Cycle: The Unending War Between Humanity and Infectious DiseaseScribner, 2021, 320 p., $28.00

Abstract

Charles Kenny, senior fellow at the Center for Global Development, begins his history of infectious disease with a two-century old quote from An Essay on the Principle of Population (1798): “Premature death must in some shape or other visit the human race.” Malthus reasoned that the power of population was so superior to the power of the earth to produce subsistence that periodic outbreaks of “misery”—either war, pestilence, or famine—were inevitable. Kenny begins his story circa 1800 on purpose. It was an inflection point in the history of infectious disease. Two hundred years ago half of all people born in the world died before their fifth birthday; today it is one in twenty-five. Life expectancy at birth was below 30 in 1870; now it is above 70. Only recently has our ability to control infectious disease made premature death the exception and not the given that Malthus believed it to be. In chapters 2 and 3, Kenny updates Malthus's story of misery's past by noting that infectious disease actually played a relatively minor role when humans lived in hunting and gathering groups and while they gradually spread from Africa across the globe. It assumed a central role, more important than war and famine combined, only with the rise of farming and “civilization,” when humans and animals began clustering together in villages and cities. The virulence of infectious disease rose dramatically with increased density, social interaction, and trade. With over half the world's population now living in cities, and trade and travel at record levels, our current containment of infectious disease is historically unprecedented. In fact, Kenny believes, these levels of globalization and urbanization cannot exist without this containment. On this larger frame, Kenny appends specific narratives of major pandemics, strategies of containment, public health innovations, vaccines, and responses to new infections. Chapter 4 tells of the massive die-offs that happened when European explorers with their Eurasian diseases of “civilization” arrived in long isolated regions. Chapter 5 tells of the “exclusion instinct” that people repeatedly exposed to deadly outbreaks developed: treating the infected with disgust and quarantine, and fleeing them when possible. Chapter 6 examines various “cleaning up” attempts: cooking food, reducing bad odors, sequestering excrement. By tracing responses to cholera, a fecal-oral bacterial infection which first appeared as a global pandemic in 1817, Kenny documents the trial and error attempts to reduce contamination in water supplies that finally produced tangible infection control. Chapter 7 examines the similar trial and error process that produced beneficial vaccines. Chapter 8 reports the good news that arrived by the mid-twentieth century with the completion of the first stage of the sanitation and medical revolutions: city living being more healthy than rural, life becoming healthier and longer, families becoming smaller and better educated, and trade and travel making the world more interconnected and prosperous. The concluding chapters examine the vulnerability of our urban and globalized world to new outbreaks of infection. We have lost tens of millions of lives to HIV/AIDS, and face a continual emergence of new threats: avian influenza, Nipah virus, Hendra virus, Ebola, Marburg fever, Lassa fever, cryptosporidiosis, cyclosporiasis, Zika, and hantavirus. Our response often has been too late and too uncoordinated. We have allowed older foes like tuberculosis and malaria to developed multidrug resistance due to our misuse of antibiotics. Covid-19 is proving just how difficult it is to contain and control an emerging viral threat in a world like ours. Kenny argues that we need consistently good sanitation and health systems throughout the world, and better systems of surveillance, screening, isolation, and research. Our modern world simply cannot exist without it.