Between 1916-1931 a mysterious illness swept across the globe, afflicting millions, killing one-third outright and leaving another third permanently disabled. Encephalitis lethargica (also known as epidemic encephalitis) usually appeared in a person who had had recent symptoms of a sore throat or flu-like illness, and was characterized by the patient appearing to fall into a deep sleep that could last for weeks or months. Some patients were stricken so suddenly that they seemed to lose consciousness while in the midst of eating, their partially chewed food still in their mouths. Others developed oculogyric crises, with many also developing signs of Parkinson's disease. Half of those who survived (and up to 70% of children who survived) emerged with significant personality changes and/or other disabilities.
During this period the fields of Neurology and Psychiatry were expanding very rapidly, and physicians and scientists were making huge advances in their understanding of many of the diseases affecting the nervous system. However, the cause of encephalitis lethargica was never identified (though not for a lack of trying): more than 9,000 scholarly articles were written about it during the 1920s alone. Then, at the beginning of the 1930s it largely vanished, as abruptly as it had first appeared, leaving behind an awful toll in human life and misery. It quickly receded from the forefront of medical attention, as seemingly more pressing concerns were identified, and was mostly forgotten by the medical community. Its cause(s) remain shrouded in mystery to this day, even after modern scientific analysis of brain tissue samples preserved from autopsies done on the corpses of victims from the 1920s, and despite the continued appearance of sporadic cases to this day. While most researchers now believe that it was caused by the body's immune response to an infectious agent such as streptococcus or influenza which then resulted in damage to the basal ganglia, there is no certainty about this or about why it disappeared, and by extension, how another pandemic can be prevented.
Molly Caldwell Crosby's Asleep: the Forgotten Epidemic That Remains One of Medicine's Greatest Mysteries describes the pandemic through case histories of some of the patients afflicted by it, the stories of some of the physicians caring for them, and a general description of the period. Unfortunately, the book seems to meander aimlessly, interspersing repeated descriptions of the piles of garbage ubiquitous on the streets of New York City at that time with tales of the suffering of individual patients, including a very graphic description of one patient's success in horribly mutilating herself that seemed unnecessarily sensationalistic. The stories themselves are of limited interest, and unfortunately do not come together to create a coherent narrative which can successfully convey the impact of the pandemic on the society as a whole, or answer the key questions which arise, namely: what caused it, why was it forgotten, and could it happen again. While encephalitis lethargica is certainly a subject worthy of serious investigation, readers seeking answers to these questions or a sense of what life was like during that period while living in the shadow of such a terrible disease will likely come away feeling unsatisfied. Whereas John Barry's The Great Influenza, which describes the influenza pandemic that killed anywhere from 20 to 100 million people between the years 1918-1920 succeeded in doing exactly that, this book, unfortunately, does not even come close.