Paul F. Clark

A note on the mode of infection in epidemic poliomyelitis

Both in experimental and human epidemic poliomyelitis the virus has been repeatedly demonstrated in the tonsils, in the nasal mucous membrane, and in nasal washings, both from fatal and acute cases. As the experimental disease can also be produced by intranasal swabbing with the active virus it seems probable that the nasal mucosa is one at least of the sources of the virus in the outside world and also the means of its entrance to the body. The marked viability of the virus under adverse conditions such as drying, low temperature, etc., must also be considered as making for a fairly well founded theory of the nasal route as one path of the virus to and from the body. The precise manner in which microörganisms enter the body through mucous membranes is difficult to establish. Because we can produce experimental poliomyelitis by the application of the active virus to the nasal mucous membrane, we have in this disease a means of determining whether the virus so applied first enters the blood stream and through this the central nervous system or whether it ascends directly along the lymphatics that unite the nasal mucosa with the central meninges. In experimental poliomyelitis produced by any method of injection it is well known that the virus is present throughout the central nervous system. But after an intranasal injection, can the virus be demonstrated equally early in all regions of the cord? In order to answer this question, the nasal mucous membrane of a Macacus rhesus monkey was swabbed lightly with a portion of ground cord from a recently paralyzed monkey. The monkey was killed at the end of 48 hours and the following portions of the central nervous system were removed separately and aseptically: (I) the olfactory lobes with small portions of the adjacent brain substance, (2) the medulla, and (3) pieces of the cord at different levels including the cervical and lumbar enlargements.