328 TUBERCULOSIS 



and by its return in small lots to a number of farms may spread 

 tuberculosis among hogs to which the skimmed milk is fed raw. 

 Mohler and Washburn have recently dealt with this subject in a 

 paper presented at the 44th annual meeting of the American Veterinary 

 Association in Kansas- City. According to their figures, in three 

 cities in one of the leading dairy States, from 3.1 to 6.4 per cent, 

 of all hogs slaughtered were found affected with tuberculosis. Hogs 

 also frequently contract tuberculosis by being fed on the same premises 

 with, tuberculous cattle, or by being allowed to feed on offal from 

 slaughter houses or to devour the carcasses of cattle dead from 

 tuberculosis. In a case cited by Mohler and Washburn of a hog 

 raiser who fed 40 hogs on the carcass of a cow dead from tuberculosis, 

 31 of the 40 had to be condemned for tuberculosis when they came 

 to be slaughtered. Hogs also easily acquire tuberculosis when they 

 are taken care of by tubercular persons who cough and spread their 

 sputum promiscuously in the pigpens. 



Modes of Infection and Transmission. It was formerly believed that 

 tuberculosis was most frequently inherited from parents by the 

 offspring. This view has now been entirely abandoned and the 

 inhalation and the ingestion of tubercle bacilli are recognized as 

 the most frequent modes of infection. 



* Inhalation. In man, tuberculosis is most frequently, and in adults 

 almost exclusively, contracted by the inhalation of tubercular material 

 from previously infected individuals. The sputum coughed up at 

 frequent intervals by patients suffering from pulmonary tuberculosis 

 contains many millions of tubercle bacilli. These may be inhaled 

 directly with fine moist particles floating in the air for some time or 

 the sputum may be dried out and pulverized and the dust particles 

 inhaled. ('It was first shown by Cornet that the dust accumulating in 

 rooms, wards, barracks, prisons, etc., where consumptives had been 

 allowed to spit on the floor, contained live, virulent tubercle bacilli. 

 Ever since that timejefforts have been made throughout the civilized 

 world to prevent consumptives from spreading their tubercular 

 sputum promiscuously and to enforce the immediate destruction of 

 the infected sputum by collecting it in proper receptacles containing 

 a proper antiseptic. This simple measure has probably contributed 

 more to the reduction of pulmonary tuberculosis than any other 

 single measure. /There are two theories as to the development of 

 tuberculosis from inhaled tubercle bacilli. According to the older, 

 more generally accepted view, the tubercular process develops directly 

 in the pulmonary alveoli. According to a more recent view, the 

 tubercle bacilli are first absorbed through the bronchial mucosa, taken 

 up by the lymphatics, and carried to the bronchial lymph glands, 

 where they multiply and from which point they later invade the 

 C parenchyma of the) lungs. 



Inhalation tuberculosis is also very common, among cattle. In 

 dairies a single cow coughing up tubercular material often spreads 



