ROUNDWORMS— THE NEMATHELMINTHES 161^ 



states, where the proper conditions of moisture, temperature, lack of sani- 

 tation, and personal habits made the spread of this worm very easy. 

 Today, it has been largely brought under control through a vigorous 

 program of education and sanitation. 



Its life cycle is identical to ascaris with the exception of its mode of 

 entry into the body. When the hookworm eggs leave a human body 

 they hatch into small larvae on the ground and are able to infect man by 

 boring through his skin, the most common site being through the bare 

 feet. There have been regions of our country, and are still some today, 

 where shoes are considered an unnecessary luxury, and the larvae lurk- 

 ing in damp shaded soil have an excellent opportunity to grab hold of 

 the skin when stepped on and to bore through. Once inside the body 

 they are carried by the circulatory system to the lungs where they bore 

 through, are coughed up, and swallowed, so that they end up in the 



intestine 



The Trichina Worm 



The trichina worm. Trichinella spiralis, is another of the serious para- 

 sites of man, but it does not restrict itself to regions of the country where 

 somewhat primitive living conditions exist. In fact it seems to be most 

 abundant in the heavily populated eastern states and is just as prevalent 

 in cities as in rural regions. Autopsies performed in this region reveal 

 that about 27 per cent of all the people have had the infection during 

 their lifetimes, with an average of the country as a whole being about 17 

 to 18 per cent. 



This is another one of the parasites obtained from pork and, unfortu- 

 nately, meat inspection is unable to detect the pork which carries it with 

 any degree of certainty. The little larvae are coiled up in the meat and, 

 since they are microscopic in size, it would require an extensive micro- 

 scopic examination of the meat to detect them and, even then, cases of 

 light infection could easily be overlooked, so thorough cooking of all 

 pork to be eaten is the only sure way to avoid possible infection with 

 Trichinella. 



Once the tiny larvae reach the intestine they become active and 

 quickly grow to adult size, which is only about three millimeters for the 

 female and about half as long for the males. Within two or three days 

 after being ingested they copulate and the males, their purpose in life 

 having been completed, die and pass from the body shortly thereafter. 

 The eggs hatch in the bodies of the females, and they deposit the living 

 larvae in the lining of the intestine so there will be no chance that they 

 will be carried from the body. These then find the blood stream and are 



