It might be of interest to quote Rachel Jenkins in her Introduction to Post Viral Fatigue Syndrome 1991 eds Jenkins and Mowbray quoting Acheson
At the Royal Free Hospital, no patient with poliomyelitis had been admitted to the hospital prior to the outbreak, nor was the diagnosis entertained in the initial cases. There was no apprehension about poliomyelitis among the hospital staff, but rather about infectious mononucleosis which was the early diagnosis. In spite of this the course of the disease and the type of neurological involvement was similar to that found in Los Angeles.