246 VETERINARY HYGIENE 



encouraged to court professional inquiry into the ailments of their 

 stock. The houses from which infected animals have been removed 

 must be cleansed and disinfected. 



M'Fadyean, Sheather and Edwards* have prepared a diagnostic 

 agent to which they applied the term " johnin " and which is 

 analogous to tuberculin. This agent produces a rise of temperature 

 on being injected into infected animals, but the results are unfor- 

 tunately invalidated to some extent by the fact that reactions are 

 also produced in tuberculous animals. 



Experiments on similar lines had been previously made 

 by Twort and Ingram as soon as it was found by these authors 

 that the organism could be cultured artificially. It had previously 

 been noted by O. Bang that avian tuberculin in the same way pro- 

 duces a reaction in animals infected with Johne's disease. Should 

 cases appear in a herd it would appear to be advisable to subject 

 the whole of the animals to a preliminary tuberculin test with the 

 object, if possible, of ruling out tuberculosis. After an interval 

 of a month non-reacting animals might then be tested with johnin, 

 and any then reacting should be regarded as infected with Johne's 

 disease. 



TETANUS. 



Tetanus (lockjaw) is a disease caused by a specific micro- 

 organism, the bacillus of tetanus, discovered by Nicolaier in 1884, 

 and is characterised by spasmodic contractions of the voluntary 

 muscles of various parts of the body. 



The tetanus bacillus is a strictly anaerobic organism which 

 normally maintains a saprophytic existence in soil, and especially 

 in soil which is contaminated with horse manure. It is also said 

 to be specially numerous in swampy ground. Its very wide dis- 

 tribution is shown by the fact that Bassano found the tetanus 

 bacillus in 27 out of 43 samples of soil obtained from various parts 

 of the world. Its special association with ground contaminated 

 with horse manure is due to the fact that it is normally found in 

 the intestinal tract of the horse. 



The distribution of the disease is universal but it is much less fre- 

 quent than one might expect. It is said to be more common in warm 

 than in cold climates. It is usually sporadic, but in young animals 

 it is sometimes enzootic, for instance, in lambs and sometimes in 

 foals following umbilical infection (tetanus neonatorutn). Any 

 special incidence as to season or age is merely coincident with such 

 operations as sheep shearing, castration, &c. 



*Journ. Comp. Path., 1916, Vol. XXIX., p. 134. 



