168 Diseases of Poultry 



may have more or less catarrh and difficulty of breathing 

 for a long time. 



Etiology. — The cause of this disease like that of nasal 

 roup is still a disputed question.^ All of the organisms re- 

 ported as causing the former disease have also been credited 

 by one or another investigator with producing diphtheritic 

 roup also. Whatever the nature of the causal organism the 

 disease is certainly strictly contagious. It never appears 

 except as a result of infection from a previous case. 



Methods of Infection. — Birds may be infected by polluted 

 food, drinking water or litter and probably also by dust con- 

 taining particles of the dried secretions. The disease may 

 be introduced into a flock by introducing infected stock. 

 Occasionally the infection may be carried on implements or 

 on the shoes of persons coming from infected yards. The 

 first symptoms appear in from three to five days after ex- 

 posure to contagion. 



Treatment. — The best treatment is of course prevention. 

 The same safe-guards suggested under nasal roup are also 

 effective against diphtheria. 



Two general lines of treatment for diphtheritic roup have 

 been used with more or less success. (1) Local treatment of 

 the diseased parts with disinfectants, and (2) vaccine and 

 serum treatments. The cost of application of either of these 

 makes them at present economically inadvisable for ordinary 

 stock. 



(1) Disinfectant Method. — In early stages of the disease 

 the painting of the diphtheritic patches with tincture of 

 iodine is sometimes sufficient. If the false membranes per- 

 sistently reappear, as they are very likely to do, they may be 

 burned away with 50 to 75 per cent hydrochloric acid or with 

 silver nitrate. Great care should be taken not to touch un- 



1 Cf. references cited supra, p. 160. 



