240 Annual Report for 1906 of Royal Veterinary College. 
disease spreads ; indeed, it is obvious that, given a single case 
of the disease, an actual outbreak, comprising numerous 
simultaneous or successive cases, is likely to be the result 
unless special precautions are taken to isolate the affected 
animal and destroy its excrement. A point upon which we 
at present possess no information is the capacity of the bacteria 
for retaining their vitality in the outer world when they have 
been voided from the bowel. Upon this will depend the 
difficulty of disinfection and the length of time for which 
infected premises or pastures will remain dangerous. 
Diagnosis . — In a previous Annual Report reference was 
made to cases of diarrhoea and wasting in cattle caused by 
the presence of minute worms in the fourth or true digestive 
stomach, 1 and the account of the symptoms of this parasitic 
gastritis there given would with little or no alteration apply to 
the present disease. That there occurs in cattle as well as in 
sheep a genuine parasitic gastritis caused by worms there can 
be no doubt, but it is quite possible that hitherto many cases 
of Johne’s Disease have been confounded with parasitic gastritis, 
the latter disease being diagnosed simply from the diarrhoea 
and emaciation. It is well known that small numbers of 
various round worms may be found in the true stomach in 
apparently healthy cattle, and it would be a mistake to attach 
any pathogenic importance to worms in that position unless 
they are present in large numbers. In future there will be 
no difficulty in distinguishing between parasitic gastritis and 
Johne’s Disease when an opportunity is afforded to make a post- 
mortem examination. The peculiar thickened and wrinkled 
condition of the mucous membrane in the latter disease is by 
itself a fairly reliable guide to diagnosis, and when any doubt 
remains, that can readily be resolved by searching the scrapings 
from the mucous membrane for the characteristic acid-fast 
bacilli. 
While the animal is still alive diagnosis is not so easy. 
Naturally it would occur to one to search the faeces for acid- 
fast bacteria in any suspected case, but a difficulty here 
arises from the fact that other species of acid-fast bacteria 
which grow on some of the grasses may be found in the excre- 
ment of perfectly healthy animals. Such acid-fast “ grass 
bacilli,” however, are seldom to be found in any considerable 
number in the faeces, and therefore when large numbers of 
acid-fast organisms, many of them collected together in groups, 
are found in the faeces of an animal suffering from diarrhoea 
and wasting, there would probably be little risk of error in 
diagnosing the case as one of Johne’s Disease. 
1 Journal R.A.S.E., Vol. 64, 1903, pp. 280-282. 
