The Great Influenza: The Epic Story of the Deadliest Plague in History

by John M. Barry

ARDS by no means accounts for all the influenza deaths in 1918 and 1919, or even for a majority of them. It explains only those who died in a few days, and it explains why so many young healthy people died. Although influenza almost certainly killed some people in ways that had little to do with the lungs—for example, someone whose already weak heart could not stand the additional strain of fighting the disease—the overwhelming majority of non-ARDS deaths came from bacterial pneumonias. The destruction of the epithelial cells eliminated the sweeping action that clears so much of the respiratory tract of bacteria, and the virus damaged or exhausted other parts of the immune system as well. That gave the normal bacterial flora of the mouth unimpeded entry into the lungs. Recent research also suggests that the neuraminidase on the influenza virus makes it easier for some bacteria to attach to lung tissue, creating a lethal synergy between the virus and these bacteria. And in the lungs, the bacteria began to grow.