HEALTH AND DISEASE 313 



causal relation of the parasite to the cases of pernicious anemia observed in 

 infested subjects. 



The prevention of infestation with the fish tapeworm is simple and ab- 

 solutely effective. Fresh-water fishes should not be eaten raw, semi-raw, 

 cold-smoked or lightly cured in salt. Thorough cooking of fish is an abso- 

 lute prevention and can be relied upon as being a one-hundred per cent, 

 prophylactic measure. 



THE BEEF TAPEWORM 



The beef tapeworm, Taenia sagmata, occurs in its adult stage solely in 

 the human intestine where it may attain a length of about thirteen to forty 

 feet. Usually an infested person harbors but a single tapeworm, the oc- 

 currence of one worm in the intestine apparently excluding others from 

 developing. 



The life cycle of the beef tapeworm is similar to that of the fish tape- 

 worm, except that but one intermediate host, namely, a bovine, is required. 

 Human beings become infested solely as a result of eating raw or rare beef 

 containing the larval stage of the tapeworm infective to man, and cattle 

 become infested with the larval or cystic stage as a result of swallowing 

 the tapeworm eggs with feed or water that has become contaminated in 

 one way or another with the excreta of a tapeworm carrier. The life history 

 of the beef tapeworm involves, therefore, an alternation between two 

 hosts, man and the ox. 



Ranson pointed out years ago that a single individual with a tapeworm 

 is a peripatetic center of infection. Each gravid segment of a tapeworm 

 contains several thousand eggs, and several segments may become gravid 

 and expelled every day during a period that may extend over several years. 

 Thus hundreds of cattle might become infested from a single tapeworm 

 carrier, if this person happens to live in a rural district where cattle are 

 raised. 



The control of infestation of cattle M^ith the larval stages of this tape- 

 worm will inevitably result in the control of the beef tapeworm infestation 

 in man, and vice versa. Reduced to simple terms, improvement in con- 

 ditions as regards the disposal of human excreta in rural sections will pre- 

 vent cattle from becoming infested, and this in turn will tend to reduce 

 and ultimately eliminate the infestation in man. 



As an example of the unsanitary conditions that prevail in some rural 

 sections of the United States, particularly as regards the disposal of human 

 excreta, an outbreak of larval tapeworm infestation in cattle, technically 

 known as cysticercosis, was investigated by the Bureau of Animal Industry 

 a number of years ago with the following results: 



Following the detection under federal meat inspection procedure of 

 a heavy infestation of cysticercosis in 3 lots of cattle which came from the 



