DISEASES OF ANIMALS 



113 



are all forms of tuberculosis which oc- 

 cur in domestic animals and man mere 

 variations of one and the same disease, 

 which may be transmitted from animals 

 to man and from man to animals? If 

 transmission between man and animals 

 is possible, to what extent does this oc- 

 cur? Is the consumption of milk and 

 meat of tuberculous animals dangerous? 

 What is the practical value and relia- 

 bility of the tuberculin test and what 



are the best methods for adoption on a 

 large scale to control or eradicate the 

 disease ? 



Opinions favor contagion — Summa- 

 rizing the almost innumerable articles 

 on tuberculosis, it may be stated that, as 

 the result of extensive and careful 

 studies and experiments by a large num- 

 ber of trained investigators, it is cer- 

 tain that tuberculosis is a contagions 

 disease, due to the presence of the tuber- 



cle bacillus and that the disease attacks 

 a greater number of animals than any 

 other disease. The tubercle bacillus may 

 be isolated from diseased tissues, stud- 

 ied in pure cultures and used for inoc- 

 ulation of laboratory animals or ordi- 

 nary farm animals, in which the disease 

 is invariably produced as the result of 

 inoculation. The tubercle bacillus is 

 also present in actively developing tuber- 

 cles in animals affected with the disease. 

 Dispute as to wholesomeness op 

 meat and milk — Kef erring next to the 

 disputed point regarding the unity or 

 plurality of the disease, it should be 

 said that Koch and his disciples still 

 maintain that the bovine and the human 

 forms of the bacillus are distinct and 

 that human tuberculosis is rarely trans- 

 mitted to cattle. The Koch school also 

 maintains that bovine tuberculosis is so 

 different from the human form that 

 there is practically no danger in eating 

 the meat of tuberculous cattle and little 

 or no danger in drinking the milk of 

 tuberculous cows. At the otber extreme 

 we have Von Behring and Lis disciples, 

 who assert that human tuberculosis is 

 in most instances acquired from cattle, 

 usually by drinking the milk of tubercu- 

 lous cows at an early age. It is main- 

 tained that children thus infected may 

 not develop apparent symptoms of the 

 disease until they reach an adult age. 

 Between these two extremes we have 

 various gradations of opinion. The 

 matter is fortunately not left in such 

 an unsatisfactory state as would be in- 

 dicated by these extreme positions. 

 Hundreds of the most careful experi- 

 ments have shown beyond question that 

 tubercle bacilli obtained from man may 

 produce the disease when inoculated into 

 cattle. There is also a mass of circum- 

 stantial evidence sufficient to convince 

 the ordinary individual that the milk 

 of tuberculous cows is dangerous and 

 capable of infecting children or even 

 adults. The tubercle bacilli may be 

 found in such milk and the milk of 

 tuberculous cows produces the disease 

 in animals after inoculation, and also 

 in pigs and calves when they are al- 

 lowed to drink it. According to recent 

 experiments, however, it appears that 

 under ordinary circumstances both ani- 

 mals and man become infected, in a 

 majority of cases, by taking the tuber- 

 cle bacilli into the alimentary tract in 

 the food, rather than by taking bacilli 

 into the lungs with the inspired air. 



