PARASITES — SCHWARTZ 423 



these parasites out of a total annual slaughter of about 20 million or 

 more head. The latest available figure, for the fiscal year 1954, shows 

 that 17,400 beef carcasses were found to be infected with these tape- 

 worm cysts out of a total slaughter of approximately 26 million 

 bovines inspected. 



Inasmuch as the habit of eating rare beef is rather well established 

 in this country and the tapeworm cysts in question are injurious to 

 health, beef carcasses are regarded as unfit for human consumption 

 under Federal meat inspection whenever these bladder worms are 

 discovered in them. If only one dead or degenerated cysticercus is 

 detected, and this often is the case when the parasite is located in the 

 heart muscle, or when only one or a few live cysticerci are found, the 

 carcass is not condemned. After removal with a knife of the 

 cysts that are discovered, such carcass is retained by the inspectors, 

 but before it is passed as fit for human food it must be refrigerated 

 for periods and at temperatures known to be destructive to the 

 cysticerci, or cooked at a temperature that is known to kill these 

 parasites. 



The life history of the pork tapeworm of man is essentially similar in 

 most respects to that of the beef tapeworm, except that in this case the 

 hog serves as the intermediate host. In man the pork tapeworm also 

 localizes in the intestine and usually attams a length of only about 2i/^ 

 to 5 feet or more. It follows the same pattern of development as al- 

 ready described for the beef tapeworm. 



The bladder worm of the pork tapeworm (pi. 2, fig. 2) is very com- 

 mon in swine in countries to the south of us, especially Mexico, Peru, 

 and Venezuela. In the last-named country its incidence reaches 20 per- 

 cent of the hogs slaughtered. The incidence of the adult tapeworm in 

 man in those countries is not known. In the United States this para- 

 site, never very common in hogs as far as known, and consequently un- 

 common in man, has become exceedingly rare in recent years. During 

 the fiscal year ended June 30, 1954, only 4 hogs out of a total of over 50 

 million slaughtered were found to be infected, and in the previous fiscal 

 year only 11 infected swine carcasses were found by Federal inspectors 

 out of over 57 million carcasses inspected. During the 4 fiscal years 

 preceding 1953, the average number of infected carcasses was 19 out of 

 a total annual slaughter under Federal meat inspection of about 50 mil- 

 lion swine. 



All infected swine carcasses discovered by Federal inspectors are 

 condemned. The pork tapeworm is a more serious parasite than the 

 beef tapeworm for the reason that human beings can serve as its inter- 

 mediate as well as definitive host. An infested individual might acci- 

 dentally contaminate his hands with the tapeworm eggs, transfer them 

 to the mouth, and so become infected with cysticerci. In human beings 



370930—56 28 



