TUBERCULOSIS— CONSUMPTION 391 



water; (b) via respiratory tract by the inhalation of tuber- 

 cular spray ejected by coughing or lowing infected cattle; 

 (c) via genital organs during coitus; (d) via udder through 

 teat canal; (e) via wounds (very rare; may follow castra- 

 tion), and (/) congenital tuberculosis has been noted only in 

 isolated cases. 



(a) Calves and swine are commonly infected through milk 

 from creameries, especially skim milk obtained by centrifugal 

 separation. The ingestion of cattle excrement by swine is a 

 pregnant source of infection, especially in America, where the 

 practice of allowing hogs to follow cattle is much in vogue. 

 The feeding of the offal of slaughter houses to swine is likewise 

 dangerous, as tuberculous lungs, livers, lymph glands, gastro- 

 intestinal contents, etc., are consumed. 



The bronchial exudate of tuberculous cattle, coughed up or 

 otherwise raised from the lungs, may mix with the saliva, 

 and thus tubercle bacilli are carried to feed or watering troughs, 

 bedding, etc. As most of the exudate is swallowed by the 

 patient (not expectorated as in man),. the feces become pol- 

 luted, scattering bacilli wherever dropped. Susceptible ani- 

 mals (hogs and cattle) eating or drinking substances contami- 

 nated by such discharges become infected. The same would 

 apply to any other secretion or excretion containing tubercle 

 bacilli (vaginal discharge, urine, etc.). 



(b) Infection through the respiratory organs comes from 

 the inhalation of either (a) globlets of bronchial exudate, 

 mixed with mucus and saliva, which are coughed out or 

 otherwise forcibly ejected from the nose and mouth of tuber- 

 culous cattle, or (6) of tubercle bacilli which have become 

 partially dried and are adhering to dust particles floating in 

 the air. In the former case cattle immediately next to an 

 "open" case of tuberculosis acquire the infection by close 

 contact, and in the latter, which is far less frequent, by 

 breathing' in the dried bacilli which contaminate the in- 

 spired air. 



(c) Infection by coitus may occur provided the genital 

 organs of the bull (penis, prostate, testes) or cow (vagina, 

 uterus) are diseased. This form of infection is relatively 

 rare, but more common than generally supposed. 



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