The Natural History of Human Poliomyelitis I. Distribution of Virus in Nervous and Non-nervous

Our present concepts of the nature of human poliomyelitis are based (a) on certain limited investigations of human tissues made for the most part 25 to 30 years ago when the virus was first recognized and the criteria for its identification were not always rigid, and (b) on the behavior of the virus in experimental animals, different species of which appear to behave quite differently (1, 2). The scattered existing data on the infectivity of human tissues include tests on the spinal cord, medulla, and cerebrospinal fluid, the lymph nodes including the tonsils and pharyngeal tissue, the nasal mucosa, the blood and viscera, and as regards secretions and excretions, nasopharyngeal washings and intestinal contents or stools. No virus has been demonstrated in the cerebrospinal fluid, the blood, or the viscera. Earlier reports of the presence of virus in the lymph nodes, particularly those of the mesentery, could not be corroborated by numerous subsequent tests and the explanation was offered that in the early work the lymph nodes might have been contaminated by admixture with positive tissues (3). Recently, however, the occasional presence of virus in human cervical and mesenteric lymph nodes has again been reported, although the criteria used for identifying the virus in some instances are open to question (4, 5). The early repeated positive results with the tonsils and attached pharyngeal mucosa (6-8) have not been reinvestigated in recent years and it has re-