PREVENTION 295 



is not so prevalent or so difficult to prevent by other means as 

 to make promiscuous immunization justifiable, even if possible. 

 A more hopeful though so far unproductive line of research 

 regarding the treatment of the infection lies in experiments 

 with drugs or serum to kill either the adult worms in the intestine 

 or the larvae before they begin destroying the tissues. 



Personal preventive measures against trichiniasis are easy 

 and consist simply in abstinence from all pork which is not 

 thoroughly cooked. Experiments by the U. S. Bureau of Animal 

 Industry show that trichinae are quickly destroyed by a tem- 

 perature of 55 C. (131 F.), since the body protoplasm is coagulated 

 at this temperature, but pork must be cooked for a length of time 

 proportionate to its weight in order to insure the permeation 

 of heat to the center. Experiments show that at least 30 to 

 36 minutes boiling should be allowed to each kilogram of meat 

 (2 J- Ibs.). Hurried roasting does not destroy the parasites as 

 long as red or raw portions are left in the center. Cold storage 

 for 20 days or more at temperatures below 10 F. has been shown 

 by Ransom to be destructive to trichinae. The regulations of 

 the U. S. Bureau of Animal Industry, relative to pork prod- 

 ucts customarily to be eaten without cooking, require freez- 

 ing for 20 days at a temperature of not higher than 5 F., 

 or curing in accordance with certain specified processes. 

 Temperatures above 10 F. are more or less uncertain in 

 their effects. Salting and smoking are not efficacious unless 

 carried out under certain conditions. Thorough salting is effec- 

 tive, provided the meat is left for some time for the salt to per- 

 meate it. Large pieces of pork placed in brine have been known 

 to contain living trichinae for over a month. The parasites in 

 sausages are destroyed in 24 hours by hot smoking whereas they 

 resist cold smoking for three days. 



Prevention of trichiniasis by meat inspection methods is at best 

 only partial, and, while meat inspection might help to lessen the 

 chances of the disease, it should not be implicitly relied upon. 

 Probably in an ordinary meat inspection all heavy infections 

 would be found, provided the inspector has been doing his work 

 properly. The inspection usually consists in the microscopic ex- 

 amination of a bit of muscle from tongue and diaphragm; if 

 the examination is negative, the hog is passed. Obviously light 

 infections must frequently escape notice, and the false sense of 

 security which is the result of knowledge that meat has been 



