A Report on Experimental Poliomyelitis. 



49 



3i (44i) 



A report on experimental poliomyelitis. 

 By SIMON FLEXNER and PAUL A. LEWIS. 



By employing as a virus the spinal cord from two human 

 cases of epidemic poliomyelitis, it has been found possible not only 

 to transmit the disease to monkeys, as Landsteiner and Popper 1 

 did, but by employing the intracerebral mode of inoculation, to 

 propagate the disease successfully through a long series of 

 monkeys. In this manner, epidemic poliomyelitis or infantile 

 paralysis has been opened up to experimental study. 



It has been proven conclusively that the symptoms and patho- 

 logical lesions of epidemic poliomyelitis are identical with those 

 occurring in the spontaneous disease of man. It has next been 

 shown that the virus of poliomyelitis is effective in monkeys not 

 only when introduced into the brain, but also when injected into 

 a large nerve (sciatic nerve), into the circulation, into the peritoneal 

 cavity, and beneath the skin. 



In the inoculation, in any of these ways, of the virus, a definite 

 incubation period is required before the disease develops. This 

 period has varied in the experiments from four to thirty-three days. 

 The symptoms which appear often arise suddenly, as they also do 

 in the spontaneous disease of man. The experimental disease in 

 monkeys is severe and often fatal. When recovery takes place, 

 there usually remain residues of the paralysis, similar to the resi- 

 dues which have been observed in the recovery from the spon- 

 taneous disease of man. 



The nature of the virus of epidemic poliomyelitis is indicated 

 by the circumstances, first, that it withstands the action of pure 

 glycerine for at least one week, and second, that it can be passed 

 through a Berkefeld filter. In other words, the virus has, thus 

 far, not been demonstrated certainly under the microscope. It is 

 so small that it passes quite readily through a mechanical filter, 

 and so resistant that it withstands the action of glycerine in a 

 manner similar to the viruses of vaccinia and rabies. The present 

 indications are, therefore, that this virus is like the viruses of the 

 diseases mentioned and belongs to the group of optically invisible 

 causes of disease. 



1 Landsteiner and Popper : Zeit. f. Immunitdtsforsch., Orig., 1909, ii, 377. 



