No. 7. DEPARTMENT OF AGRICULTURE. 83 



EXPLANATION OF PRINCIPALS. 



The fundamental thought is that meat should not be used for food if it con- 

 tains tubercle bacilli, if there is reasonable possibility that it may contain 

 tubercle bacilli or if it is impregnated with toxines of tuberculosis. Nor should 

 meat be used for food if the condition of the animal from which it comes is such 

 as to excite nausea or disgust or if the flesh falls below the usual standard of 

 food value. 



On the other hand, if the lesion is local, if there is no distribution of tubercle 

 bacilli through the b>ood or by other means to the muscles or to parts that may 

 be eaten with the muscles, if there is no intoxication, and if the animal is well 

 nourished and in good general health, there is no proof, or reason to suspect, 

 that the flesh is in the least degree unwholesome. 



In Germany, and in some other countries, there are five ways of disposing of 

 the flesh of a tuberculous animal, depending on the severity or extent of the 

 lesions: (1) the entire carcass may be condemned outright, (2) a part of it may 

 be condemned, (3) it may be sterilized and sold as cooked meat, (4) it may be 

 sold with a declaration to the purchaser of its below-standard and possibly dan- 

 gerous quality, or, finally, (5) it may be released to be sold without restriction. 



Since, in this country, the third and fourth m.ethods above enumerated, are 

 not likely to come into use, the American meat inspector must either (1) con- 

 demn the entire carcass or (2) condemn a part of the carcass or (3) pass the 

 flesh for sale without restriction. Therefore, if the meat cannot unqualifiedly 

 be passed as sound and wholesome, so much of it must be condemned as there is 

 reason to suspect may be unsound or unwholesome. 



The term "local" as used to qualify a lesion of tuberculosis is designed to 

 signify: confined to the point of origin and to the parts in structural or lym- 

 phatic connection therewith. Thus, tuberculosis of a lung, the pleura, the 

 diaphragm and of the mediastinal and bronchial lymphatic glands would be 

 local. Tuberculosis of the peritoneum could be local even though the serous 

 covering of several of the abdominal organs were involved. 



By "generalized tuberculosis" is meant a condition in which the virus of the 

 disease has been distributed by the blood. This condition is particularly im- 

 portant in meat inspection because tubercle bacilli, having entered the circu- 

 lation, are widely scattered, and it is precisely in this way that the muscles 

 and inter-muscular connective tissue and lymphatic glands are most likely to 

 become infected. In generalized tuberculosis we must always reckon with the 

 possibility of infection of the meat. 



If tubercle bacilli enter the circulation, they are most likely to be filtered out 

 and to produce lesions in the lungs. Following the lungs, named, approxi- 

 mately, in the order of frequence of infection, are: the liver, spleen, serous 

 membranes, kidneys, lymphatic glands, udder, bones and joints. Some of these 

 organs, as the spleen and kidneys, are almost never infected except by bacilli 

 carried to them by the blood. 



The most constant evidence of generalization is the presence in both lungs of 

 numerous evenly distributed tubercles of approximately the same size. This 

 characteristic may be masked in cases in which there have been several erup- 

 tions of tubercle bacilli into the systemic circulation, producing several crops 

 of tubercles of different ages. 



The presence of tubercle bacilli in the blood cannot be detected in the ordinary 

 course of meat inspection. It is possible only to detect the result of the seeding 

 of the organs with tubercle bacilli carried by the blood. But, usually, this 

 result does not develop to a point perceptible to the naked eye for from two to 

 four weeks after the seeding. In the meantime, the bacilli have disappeared 

 from the blood and no effect of the incubating generalization is visible. As it is 

 from extensive and acutely progressive lesions that this complication most fre- 

 quently occurs, it is necessary to treat animals containing such lesions as 

 though they were positively dangerous. 



Tuberculous intoxications may be shown by fever and cachexia, or by either 

 separately. Fever with tuberculosis is always ground for condemnation and 

 emaciation in a tuberculous animal, occurring either slowly or rapidly, renders 

 the flesh unfit for use as food. 



Tuberculosis of the serous membranes, especially of the perietal pleura or 

 peritoneum, involves a region that may be eaten. The location upon the costal 

 region is especially to be considered because the disease area may be rolled into 

 the interior of a rib roast and it has been shown by the Royal Commission on 

 Tuberculosis that the inside of a rare roast of beef may not have been heated 

 sufficiently during cooking to kill tubercle bacilli. 



The lymphatic glands corresponding to a region or organ cannot become tu- 

 berculous excepting by the passage of tubercle bacilli from the part containing 

 lymphatics tributary to the glands. Hence, tuberculous portal lymphatics de- 

 note that tubercle bacilli have passed through the liver and, usually, careful 

 search will show traces, or clear evidence, of their presence in that organ. 



Similarly, lymphatic glands in other locations, as along the intestines, or 

 in the prescapular region, may show the passage of tubercle bacilli through 

 structures that show to the meat inspector no evidence of existingr tuberculosis. 



