A longtime Flublogian friend who goes by the handle of Slovenia recently sent me a link to a 1959 report in the American Journal of Medicine, titled The Clinical Syndrome Variously Called Benign Myalgic Encephalomyelitis, Iceland disease, and Epidemic Neuromyasthenia. It describes a polio outbreak in Los Angeles and a strange outbreak of something that looked like polio in healthcare workers—including a 19% attack rate in nurses.
The article describes some 14 such outbreaks, not all in healthcare settings, including one in Akureyri, Iceland in 1948-49. That led to the term "Akureyri disease," later changed to Iceland disease. It seem to have some connection to what we now call chronic fatigue syndrome.
I don't know if it's anything more than a superficial similarity of symptoms, but it's still an intriguing similarity. And since I was in LA County General with real polio just 14 years after that hospital was dealing with an earlier polio outbreak, I can well imagine how those poor healthcare staff felt as their colleagues began to fall ill as well.