VI DISEASES OF THE COW 123 



(a) The most telling argument against the bovine scarlatina 

 view, the absence of scarlet fever amongst the rest of the Derby 

 cows, is explainable. On this hypothesis we can accept the view 

 that this outbreak of teat and udder ulceration was very widespread. 

 It was due to a bovine disease of an infectious character to bovines, 

 having nothing to do with scarlatina. Human cases of scarlatina 

 were, therefore, only traceable from such cows when, as in the three 

 sent to Hendon, superadded scarlatinal organisms were present. 



(b) One of the strongest arguments against a purely human 

 origin was the prolonged infectivity of the milk. The opponents 

 of the bovine origin showed the possibility of human infection. 

 It, however, seems to have been established that none of the 

 milkers or others who came into regular contact with the milk, or 

 the cows, suffered, or had suffered from scarlet fever. The only 

 human infection possible was at the most intermittent, and probably 

 only occurred once or twice. On a well-managed farm, such as this 

 farm was shown to be, to produce prolonged infectivity we must 

 postulate a human factor at work all, or nearly all, the time. 

 There is admittedly not the slightest evidence of prolonged human 

 infection. If, however, we assume that in some now undiscoverable 

 way (possibly in transit to the farm) the already present ulcers and 

 sores of the three cows were infected with the organism of scarlet 

 fever this difficulty vanishes. 



(c) The most striking fact established by Power in favour of 

 the bovine theory was the definite association of scarlet fever cases 

 with the movements of these three cows. This is obviously 

 explained by the hypothesis of their being locally infective. 



(d) The opponents of the bovine theory are confirmed in their 

 view by the continued rarity of such conditions. On the hypothesis 

 the rarity of such outbreaks is easily understandable. We have 

 three factors which have to be in operation at once : cows suffering 

 from a bovine disease of the teats and udders, which will allow a 

 secondary infection with the organisms of scarlet fever ; the existence 

 of cases of scarlet fever ; means of bringing the last condition into 

 intimate relationship with the first. 



Klein's results are explainable on the supposition that he was 

 working with the original bovine disease material, and with this 

 he was able to reproduce ulcers and vesicles in inoculated calves. 



The suggested hypothesis offers a complete explanation of all the 

 essential facts of the Hendon disease, and reconciles the conflicting 

 views. 



Similarly the Glasgow outbreak ^ in 1892, said to be due to 



the Hendon disease, can best be explained on this hypothesis, 



particularly as regards the prolonged infectivity of the milk. In 



this outbreak Klein's results definitely show that an underlying 



1 Brit. Med. Journ. 1892, ii., p. 666. 



