352 ANNUAL REPORT SMITHSONIAN INSTITUTION, 195 2 



diaphragms from Corn Belt Hogs, 2 but only negative results were 

 obtained when samples from the same diaphragms were examined 

 microscopically with painstaking care. Therefore, the 1.5 percent 

 trichinous hogs discovered by microscopic inspection several decades 

 ago undoubtedly represented only part of the infected carcasses that 

 were then present in this country. 



Unlike the findings in farm-raised hogs, in which the extent and 

 degree of infection with trichinae are apparently on the downgrade, 

 those in garbage-fed hogs which, fortunately, constitute only a very 

 small percentage of the total hog slaughter in this country, continue 

 to show a high incidence and a comparatively high degree of infection. 

 Recent studies in our laboratories showed that over 10 percent of 

 garbage-fed hogs from the eastern seaboard still harbored trichinae, 

 and that the degree of infection was so high that about half of the 

 infected samples were detected by careful microscopic inspection 

 alone. 



Under Federal meat inspection, parasites and the lesions they pro- 

 duce in edible portions of carcasses must be removed by trimming be- 

 fore the carcasses or affected parts are passed for human food. If the 

 infection or associated lesions are so extensive, however, that trim- 

 ming would be impossible or impractical, the carcass or part is con- 

 demned. Since trichinous pork does not differ in appearance from 

 noninfected pork, it follows that trichinous hogs may be passed for 

 human food, under Federal and other meat inspection, almost every 

 day. Fortunately, however, raw pork, as such, is seldom eaten in this 

 country intentionally, and then only by persons having a capricious 

 appetite, or who have become addicted to this habit because of national 

 origin or association with homes where this unhygienic dietary custom 

 prevails. Cooked trichinous pork presents no danger whatsoever, a 

 fact of which Leidy was well aware when he explained to the Phila- 

 delphia Academy of Natural Sciences in 1866 the circumstances under 

 which he first discovered trichinae in pork 20 years earlier. Actually, 

 he found these parasites in a slice of cooked pork he was eating, and 

 stated that he had already satisfied himself that such meat was safe, 

 because parasites generally were destroyed by thorough cooking. 



The Bureau of Animal Industry has repeatedly informed the pub- 

 lic that raw or inadequately cooked or cured pork is dangerous. In 

 the absence of any known system of inspection whereby trichinous 

 pork could be tagged and eliminated from the channels of trade, the 

 problem has been met in the only other way that is possible and practi- 

 cal. Through its meat inspection service, the Bureau of Animal In- 

 dustry rigidly enforces a requirement that no ready-to-eat article of 



? Since this paper was written, the Infection rate by microscopic examination of over 

 3,000 diaphragms was found to be 0.63 percent. 



