The Plague Cycle: The Unending War Between Humanity and Infectious Disease, Kenny - B

     Mankind's transition to farming and the domestication of animals altered the dynamics of our battle with disease. "Large scale infection was the poxed handmaiden of agriculture and civilization ." Over our history, "pestilence has wiped out far more lives than famine and violence combined..." Prior to the eradication of smallpox in 1980,  hundreds of millions died in the first eight decades of the century.  Nineteenth century improvements in sanitation and twentieth century advances  in science have provided the species with unimaginable improvements in longevity and good health. 

  During the Stone Age, the population of our hunter-gatherer predecessors never grew materially because of their constant movement, violence, precarious food supplies and infectious disease, as pathogens diversity has always been higher in the tropics. When homo sapiens moved together to farm and live in cities, proximity allowed "species hopping infectious killers to spread." The agro-urban diseases of measles, smallpox and malaria have been history's great killers and have "had the larger role in shaping societies and economies." Trading over distance soon added to the exchange of infectious diseases. The Roman Empire stretching from the Atlantic coast, and eventually Britain,  to Egypt was a highway of non-stop disease transmission. Plague and pandemic accompanied the declines and border failures of the later Empire. It inhibited the expansion of Islam and, in the 14th century, the Black Plague killed up to half of Europe. Perhaps the most dramatic example of disease affecting humanity was the devastation of 90% of the peoples of America by the "microbial invaders from Eurasia and Africa" after the Spanish arrival in the New World. Disease, particularly typhus, stymied Napoleon in Egypt and Russia, and one of his lieutenants in Haiti.

  For most of history the primary way to avoid illness was to isolate, segregate and quarantine the sick. The 19th century's rapid industrialization and concomitant increase in urban population spurred the creation of clean waters systems and sewers. The ultimate game changer has, of course, been vaccination. The earliest recorded activities were in the 18th century in China and Constantinople. Europe  followed suit in the 19th century. WWII saw the American introduction of antibiotics in the form of penicillin. Life expectancy around the world doubled in the 20th century. The connectedness of the world may be resetting the equation between microbes and man. Both AIDS and Covid-19 were quickly spread around the world. Similarly, anti-vaccination believers are hurting the general health of the public, as is over cleaning and keeping children away from 'normal' microbe exposure. Overuse of antibiotics, in both humans and animals, leads to viruses that resist the medicines.  These trends can and should be stopped. "The massive decline in premature death is something we should celebrate and protect as humanity's greatest triumph."