The secondary stage of the tapeworm is sometimes injurious to the other 

 host also, forming what is called a bladder-worm. Sometimes the human or- 

 ganism serves as the secondary host. In that case the bladder-worm may 

 cause serious destruction of some tissue or organ. 



Parasites of the roundworm group embed themselves in the muscles of a 

 mammal. One of these, Trichinella, usually alternates between man and pig, 

 producing trichinosis in human beings, and the condition known as "measly 

 pork" in the meat industry. 



Tapeworm, trichinella and hundreds of other parasitic species find their 

 sustenance and their way of life in the food eaten by mammals and other 

 larger animals — the food and its migrations through the bodies of these 

 animals. We can control many of these parasites (1) by individual or family 

 care in the selecting and cooking of meat, and (2) by public regulation and 

 inspection of the raising of food animals and the preparation and marketing 

 of meat products. 



The Hookworm Early in this century investigations conducted under 

 the'dircction of Dr. Charles W. Stiles (1867-1941), of the United States Public 

 Health Service, disclosed the fact that the "poor whites" of our Southern 

 states were suffering from an intestinal parasite, the hookworm. This round- 

 worm depleted their energies, emotional and intellectual, as well as physical 

 (see illustration, p. 615). The announcement of this discovery was at first 

 ridiculed; nobody would take the "laziness germ" seriously. Self-righteous 

 people said, "Laziness is laziness, and that's all there is to it," or they said, 

 "There's no use blaming sickness or worms for being lazy." Yet the fact 

 remains that with the removal of the parasite these white folks appear to be 

 equal to the best stocks in the country. 



In some districts almost every inhabitant was infected when the investiga- 

 tions were made. The remedy and the prevention are comparatively simple. 

 The parasite can be driven from the host by the use of thymol and epsom salts. 

 Where sanitary privies and modern toilets are installed, the parasites are un- 

 able to multiply in the surface soil and come under complete control. But 

 in the South, where nearly a third of our population Uves and where intes- 

 tinal parasites are most prevalent, 15 per cent of the farm homes had no 

 toilet facilities of any kind in 1940. 



Ticks and Mites The itch often causes extreme irritation, but its chief 

 danger is the great temptation to scratch, for that may lead to infection by 

 some more dangerous parasite. The little animal that causes the itch is a 

 mite, a nearly invisible relative of the spiders. Preventing the itch is largely a 

 matter of personal cleanliness. Another skin parasite related to spiders is the 

 tic\, which is about an eighth of an inch long. This bloodsucker may produce 

 a painful bite, but its greatest danger is as a possible carrier of disease germs 

 (see illustration opposite). 



616 



