844 THE FILTRABLE VIRUSES 



[In America and on the Continent the results appear to be most satisfactory. 

 When used at an early stage of an outbreak 2*9 per cent, of the treated animals 

 died against 93 per cent, of the untreated (Uhlenhuth) : in herds where hog- 

 cholera existed 13 per cent, of the treated died against 75 per cent, of the 

 untreated : in herds which had been exposed to disease 4 per cent, of the 

 treated died against 89 per cent, of the untreated (Dorset).] 



SECTION XII. THE VIRUS OF ACUTE ANTERIOR POLIOMYELITIS. 1 



Syn. Infantile paralysis. Fr. La poliomyelite epidemique : Maladie de 



Heine- Medin. 



Landsteiner and Popper in 1908 were the first to show that acute anterior 

 poliomyelitis could be reproduced in monkeys by inoculating into the peri- 

 toneal cavity an emulsion of the spinal cord of an affected individual. Leva- 

 diti and Landsteiner further demonstrated that the effect produced in the 

 monkey was not simply the result of the inoculation of a toxin but was a 

 true infection. These observations were soon confirmed by Flexner and 

 Lewis in New York, Leiner and Wiesner in Vienna and subsequently by many 

 other observers. 



The virus of acute anterior poliomyelitis belongs to the group of filtrable viruses : 

 if pieces of the spinal cord of a child who has died of the disease be emulsified in 

 normal saline solution and the emulsion be filtered through a Chamberland, Berke- 

 feld or Reichel filter (in vacua under a pressure of 30-40 cm.) the filtrate inoculated 

 into susceptible animals will be followed by the symptoms and lesions of the 

 disease ; moreover the virus can be passed from animal to animal, a fact which 

 proves that it is a living proliferating organism. 



The organism has never been seen neither have attempts to cultivate it succeeded : 

 if a virulent filtrate be sown on culture media the cultures remain sterile, and if a 

 drop of the filtrate be examined microscopically no organism can be seen in it. 



The virus can be preserved unaltered in the ice-chest in a glycerin-saline solution 

 (1 to 2) for considerable periods of time (5 months, Rcemer and Joseph) and in 

 this respect resembles the viruses of rabies and variola vaccinia. Emulsions of 

 virulent cords will retain their infectivity for at least a fortnight when dried in 

 vacuo over sulphuric acid (Levaditi and Landsteiner). Similarly portions of the 

 spinal cord placed in bottles over potash and kept in the dark are found to be infective 

 after the lapse of 24 days. 



The organism of acute anterior poliomyelitis is localized chiefly in the spinal cord, 

 medulla oblongata and intervertebral ganglia but has been found in the cervical 

 cortex (Flexner and Lewis) and in the olfactory bulbs (Levaditi and Landsteiner, 

 Flexner). It does not under ordinary circumstances remain long hi the cerebro- 

 spinal fluid or in the blood-stream. 



Experimental infection. 



Apes and monkeys are practically the only animals susceptible to infection 

 with the virus of acute anterior poliomyelitis ; most laboratory animals 

 appear to be immune, though in some cases atypical symptoms and lesions 

 have been produced in rabbits. 



Methods of infection. Monkeys can be experimentally infected by almost 

 any method of inoculation : intra-peritoneal, intra-cerebral, intra-ocular, 

 intra-venous, by the nasal mucous membrane, etc. The disease can also be 

 set up in these animals by feeding them upon infected material (Leiner and 

 Wiesner). It is to be noted however that in Levaditi and Landsteiner 's 

 experience the disease cannot be produced by rubbing the virus into the 

 scarified surface of the skin and that sub-cutaneous inoculation cannot be 



1 This section has been added. 



