EPIDEMIC POLIOMYELITIS 301 



rather than pass through the pores. After all precautions have 

 been taken itimust be shown that the pathogenicity of the filtrate 

 is due to a living organism and not a toxin. This may be deter- 

 mined by inoculating a series of animals with the filtrate and later 

 inoculating another series of animals with a filtrate of material 

 obtained from the first series. 



Epidemic Poliomyelitis. The disease occurs both sporadically 

 and in epidemic form in all quarters of the world and affects chiefly 

 children under five years of age. The mortality is low, but about 

 75 per cent of the survivors are permanently deformed. The 

 chief symptoms of the disease are fever, sometimes accompanied 

 by sore throat and followed after a few days by paresis and 

 paralysis. 



Nothing was definitely known of the etiology of the disease 

 until, in 1909, Landsteiner and Popper in Vienna reported its 

 transmission to apes by the intraperitoneal injection of an emulsion 

 of the spinal cord of a child who had died of infantile paralysis on 

 the fourth day of illness. In the same year Flexner and Lewis 

 transmitted the disease to monkeys by intracerebral injections 

 and found that the brain and cord of the inoculated animals were 

 infective for other monkeys. 



In 1911 Flexner and Noguchi announced that they had succeeded 

 in cultivating the virus in human ascitic fluid to which had been 

 added a small piece of fresh sterile rabbit kidney. Growth takes 

 place at first only under anaerobic conditions. Fragments of in- 

 fected brain or cord or a filtrate of nerve tissue may be used for 

 inoculating the medium. After about five days' incubation at 

 37 C. growth appears as an opalescent haze upon the fragment 

 of tissue. Film preparations treated with Giemsa stain show the 

 organisms as minute bluish or violet round bodies, measuring about 

 0.2 p in diameter and arranged in pairs, chains, or groups. They 

 appear to have a special affinity for nerve tissue. In an infection 

 they are contained in the brain, spinal cord, salivary glands, mucous 

 membranes of the nasopharynx, and very rarely in the cerebro- 

 spinal fluid or the blood. They are not weakened by freezing 

 and will withstand 1 per cent carbolic acid for at least five days. 



