16 JOHNKS DISEASE 



According to the returns of the Board of Agriculture 

 for the year 191 1, there are in Great Britain about 

 4,200,000 head of cattle over two years of age ; of these 

 2,825,000 are cows in milk or in calf. If we take the 

 low estimate of i per cent, of the milch cows alone as 

 being affected with, and dying from, Johne's disease 

 (or sold to a butcher when they should be at their best 

 for milk purposes), and if we assume the loss on each 

 to be that estimated above — i.e.^ ;^20 — then the annual 

 loss in Great Britain would be over ^500,000. But 

 this takes no account of 1,250,000 beef animals, or of 

 the extra value of pedigree animals, or of the possi- 

 bility of many infected animals among the 26,000,000 

 sheep in Great Britain. 



Bang quotes the figures in a circular issued by the 

 Kustos Insurance Company, which insures a great 

 number of cattle in Denmark (October, 1909). Accord- 

 ing to Bang, it is estimated that of 40 herds of Jersey 

 cattle insured for about 1,000,000 kroner, 150 animals 

 died in 29 herds. As compensation for deaths from 

 this disease alone, the company paid out 28,000 kroner, 

 which represents 3-5 per cent, of the total value for 

 which the animals were insured. Presuming that the 

 disease is equally prevalent among the 2,825,000 milch 

 cows in Great Britain, and valuing them at ;^20 per 

 head, the loss per annum involves over ;^i,ooo,ooo, 

 and since it is unlikely that the disease is twice as 

 prevalent in Denmark as in this country, our estimate 

 of ;^5oo,ooo is probably too low. 



Etiolog-y. — As was mentioned when dealing with the 

 history of the disease, the association of a thickened 

 intestine with symptoms of chronic diarrhoea and 

 wasting had often been observed prior to Johne and 

 Frothingham's discovery of acid-fast bacilli in the 

 lesions. When B. Bang described the condition at 



