CHAPTER V. 



HYDROPHOBIA, LYSSA, OR RABIES. 



HYDROPHOBIA, lyssa, or rabies is a specific infectious 

 toxic disease to which dogs, wolves, skunks, and cats are 

 highly susceptible, and which, through their saliva, can be 

 communicated to men, horses, cows, and other animals. 

 The means of communication is almost invariably a bite, 

 hence the specific organism must be present in the saliva. 



The infected animals manifest no symptoms during a vary- 

 ing incubation period in which the wound heals kindly. 

 This period may be of twelve months' duration, but in rare 

 cases may be only a few days. The average duration of the 

 period of incubation is about six weeks. 



Toward the close of the incubation period an observable 

 alteration occurs in the wound, which becomes reddened, 

 may suppurate, and is painful. The victim has a sensation 

 of horrible dread, which passes into wild excitement, with 

 paralysis of the pharyngeal muscles and inability to swallow. 

 The wild delirium ends in a final stage of convulsion or 

 palsy. The convulsions are tonic, rarely clonic, and finally 

 cause death by interfering with respiration. 



During the convulsive period much difficulty is experi- 

 enced in swallowing liquids, and it is supposed that the 

 popular term " hydrophobia " arose from the reluctance of 

 the diseased to take water because of painful spasms caused 

 by the attempt. 



Pasteur* and his co-workers, Chamber-land and Roux,f 

 found that in animals that die of rabies the salivary glands, 



* "Compte-rendu Acad. des Sciences," Paris, 1889, cvm, p. 1228. 

 t Ibid., Oct. 26, 1885. 



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