PROPHYLAXIS 45 



infection ; cattle or sheep, however, should be kept off 

 land known to be infected. 



Sheep must be considered as carriers of the infection ; 

 and in carrying out prophylactic measures on a farm 

 these animals should be inspected. Weakly and 

 emaciated members of the flock should be carefully 

 isolated, and if showing signs of diarrhoea, the faeces 

 should be examined microscopically. Such animals 

 should also be tested with a diagnostic vaccine pre- 

 pared from Johne's bacillus. 



In buying new stock, whether sheep or cattle, their 

 history should, if possible, be known, and cattle should 

 certainly be tested before being allowed to run with 

 other animals on the farm. In the case of cows known 

 to have come from an affected farm, it might be ar- 

 ranged in a warranty that the purchases have passed 

 a test with a specific vaccine shortly before the sale. 

 To be really effectual, all these prophylactic measures 

 should be carried out under the personal supervision 

 of a veterinary surgeon, and the best means of eradi- 

 cating the disease is to test the whole herd every three 

 months in order to get rid of reacting animals before 

 they commence to excrete the causal bacilli in their 

 faeces in large numbers, and so expose their neighbours 

 to the risk of infection. 



