Tubercle Bacilli Types. 



103 



What Danger Threatens Man Through Ingestion of Milk Which 

 Contains Bovine Tubercle Bacilli? 



In order to answer this question it is necessary to refer 

 to the development of tuberculosis in man, and to consider the fac- 

 tors which are necessary for an infection of his body. 



These factors in addition to the toxicity of the infective agent, 

 and the quantity in which it has the opportunity to enter the body, 

 depend upon the avenues of infection which it takes and the local 

 and general resistance of the attacked individuals towards the spe- 

 cific infective agent. 



There is perfect agreement relative to the virulence of the 

 bovine tubercle bacillus for man. The bovine tubercle bacillus is a 

 strain of the tubercle bacillus with such pregnant characteristics 

 that it is almost invariably possible to classify it separately from 

 other strains when obtained in culture, that is, to distinguish the 

 bovine tubercle bacillus from the bacillus of the human type. 



These bacilli are distinguished as the typus bovinus and 

 typus humanus (only these two types need to be considered from 

 the standpoint of milk hygiene) which are characterized by the fol- 

 lowing peculiarities : 



Typ. Bovinus. 



The growth is delicate and 

 in the thin film small wart-like 

 colonies develop; on bouillon a 

 mesh-like fine membrane with 

 wart-like prominences develops 

 proliferating downward, or a 

 membrane of tissue-paper thick- 

 ness results; the bouillon is 

 probably neutralized and finally 

 becomes alkaline. 



The bovine tubercle bacil- 

 lus is as a rule of greater 

 toxicity for smaller mammalia. 

 Rabbits develop through intra- 

 venous injections of the bacillus 

 (0.001 gm.), a generalized tu- 

 berculosis from which the ani- 

 mals succumb inside of three 

 weeks. When 0.01 gm. is in- 

 jected under the abdominal skin, 

 it produces in a short time, gen- 

 eralized tuberculosis. 



Cattle succumb readily to 



Typ. Humanus. 



The growth is a luxuriant, 

 uniformly thick and wrinkled 

 membrane, which proliferates 

 on the wall of the tube. The 

 growth is the same in bouillon; 

 the degree of acidity of the 

 bouillon is usually at first 

 diminished, later increased. 



0.001 gm. of bacilli of the 

 human type intravenously in- 

 jected produces after months 

 only a chronic form of tuberculo- 

 sis (joints, kidneys, lungs, 

 testicles). 



The injection under the ab- 

 dominal wall produces only local 

 lesions. 



Inoculated into cattle the 

 bacilli of the human type (0.05 

 gm. subcutaneously), produce 

 only slight or no pathogenic ac- 

 tion. The process remains 

 local, and extends only to the 



