THE FILTERABLE VIRUSES 201 



connected with either disease, although many organisms 

 have been isolated, notably Bacillus alb us variolce, of Klein 

 and Copeman, and what is believed to be a protozoon, 

 the Cytoryctes variolas. It seems probable that the viruses 

 of both diseases are filterable. 



Acute Anterior Poliomyelitis (Infantile Paralysis). 

 Most cases of this disease (which may occur in a sporadic 

 and also in an epidemic form) affect children, principally 

 in the second and third years of life. The epidemic type 

 may attack older children and adults. The virus is 

 filterable, and for many months in pure glycerin keeps 

 without loss of virulence. 



Flexner and Lewis have shown that the virus can enter, 

 and is eliminated by, the mucosa of the naso-pharynx. 

 Transmission may take place by ' carriers ' who them- 

 selves remain healthy. The virus is carried by the house- 

 fly both on the surface of its body and within its gastro- 

 intestinal tract. It can also be transmitted by bed- bugs 

 and stable flies, but not, as far as is known, by fleas or 

 mosquitoes. The virus remained potent in sterile milk 

 and sterile water for at least thirty-one days, and was 

 found in a patient seven months after the onset of the 

 disease. Zappert found it in the dust of a patient's bed- 

 room. It is destroyed at 45 to 50 C. in thirty minutes. 

 The virus of infantile paralysis has not been definitely 

 cultivated, but Flexner and Noguchi thought it to multiply 

 in a medium of broth cum human serum under anaerobic 

 conditions. Diseases similar to poliomyelitis have been 

 described in horses, cows, pigs, chickens, and dogs. As 

 it is impossible, apparently, to infect these animals with the 

 human virus, the diseases are probably not identical with 

 the human one. Alexander suggests that the virus of 

 poliomyelitis may remain in the water and slime of public 

 baths. In one epidemic over 50 per cent, of one series 

 of cases had been swimming or wading in water con- 

 taminated by sewage. 



Epidemic Nephritis. Langdon Brown (R.A. M.C. Journ., 

 July, 1915) says bacteria could apparently be excluded 

 as the infective agent in the acute nephritis that occurred 

 among the soldiers of the British Expeditionary Force in 

 France, but a filter- passing ultra-microscopic organism 

 could not be excluded. The point of entrance of the 

 infection was possibly the tonsils. 



