428 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 9 



of pork imported from the United States. Dr. Stiles (13) was un- 

 able to trace definitely a single case of trichinosis occurring in 

 Germany between the years 1881 and 1898 to pork from the United 

 States. He did, however, trace about one-third of over 6,000 cases 

 of trichinosis that occurred in that country, during the/ period men- 

 tioned, to pork Avhich had been examined microscopically by German 

 inspectors and certified by them as free from trichinae. These facts, 

 elicited by the Bureau of Animal Industry, strengthened the Bureau's 

 position as regards the futility of microscopic inspection of pork as 

 an effective safeguard against human trichinosis, and led to investiga- 

 tions which established the present method of handling the trichina 

 problem under federal meat inspection procedure. 



As a result of discoveries by Ransom (10, 14) that trichinae in pork 

 could be destroyed by refrigeration for a continuous period of not 

 less than 20 days at a temperature not higher than 5° F., the estab- 

 lishment by Ransom and Schwartz (15) that the thermal death-point 

 of trichinae is 131° F. (137° F. for official purposes), and finally the 

 work of Ransom, Schwartz, and Raffensperger (16) on a number of 

 practical methods of curing various pork food products customarily 

 eaten without cooking, the following procedures have been adopted. 



Fresh pork, and ordinary varieties of cured pork intended to be 

 cooked in the home and elsewhere, are subjected to no treatment or 

 inspection, since no practical treatment to destroy trichinae and no 

 economically practical system of inspection to discover these para- 

 sites have as yet been devised. All products containing pork muscle 

 tissue, to be sold as cooked products, are heated or cooked under the 

 supervision of inspectors, according to methods which are known to 

 insure a sufficiently high temperature to destroy in all parts of the 

 meat the vitality of any trichinae that may be present. For all 

 products which are not cooked or heated to a sufficiently high tem- 

 perature, but which are nevertheless intended to be eaten by the 

 consumer without being /cooked, various alternative methods of 

 preparation are prescribed, including the refrigeration procedure 

 already mentioned, smoking, curing, drying, and other processes. 

 All the individual methods prescribed have been shown by careful 

 experimentation to be destructive to the vitality of trichinae. 



In addition to the protection thus afforded to consumers of the 

 classes of products mentioned, the Bureau of Animal Industry has 

 called attention at frequent intervals to the danger of acquiring 

 trichinosis as a result of the consumption of raw pork or meat food 

 products containing raw or inadequately cooked or cured pork muscle 

 tissue. Through leaflets, bulletins, press releases, posters, radio 

 broadcasts, and official correspondence with health officers and the 

 public generally, the facts available in the Bureau's files have been 



