Common Insect Enemies 105 



eases of modern times strike more fear into the hearts of men 

 than this virus infection which attacks the nerve cells that con- 

 trol the muscles, and which may leave its victim a cripple for 

 life. It is this crippling aspect of the disease that is so 

 frightening. Actually, polio kills fewer people than such 

 common diseases as measles, whooping cough, and mumps. 



Although it seems to have reached epidemic proportions 

 only within the present century, poliomyelitis, apparently, is 

 an old disease, and is much more prevalent than most of us 

 believe it to be. Probably most adults have had polio at 

 some time during their lives without knowing it, for contrary 

 to common belief, most cases of polio do not end in death or 

 paralysis; it is only those cases that do show the typical paral- 

 ysis that are recognized as such by most physicians. Cer- 

 tainly, many adults have protective substances in their blood 

 that immunizes them against further attack, and this indicates 

 that they probably had the disease in a mild form earlier in 

 life. 



But this knowledge doesn't help much when we see a 

 number of children suddenly stricken with the disease in its 

 violent form, and watch them die or become paralyzed. 

 What causes the disease? How is it transmitted? And 

 what can be done to prevent its spread? These are the ques- 

 tions to which we would like to know the answers. 



Apparently the virus of poliomyelitis enters the victim 

 through the mouth, or possibly the nose, and gets into his 

 alimentary tract from where it travels to his nervous system. 

 The evidence for this is that the virus has been found in hu- 

 man stools and in sewage. How then, is it transmitted? 

 Flies may be the answer, for poliomyelitis virus has also been 

 found in flies. But more dramatically still, food left ex- 

 posed to flies for from 12 to 24 hours in several epidemic 



