CHAPTER V 

 HYDROPHOBIA, LYSSA, OR RABIES 



Neurokrhyctes HydrophobIjE (Calkins) 



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 infection must be present in the 

 saliva. 



The infected animals manifest no symptoms during a varying in- 

 cubation period in which the wound heals kindly. For human be- 

 ings this period may be of twelve months' duration ; in rare cases 

 may be only a few days; its average duration 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 mus- 

 cles 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 experienced in 

 swallowing liquids, and it is supposed that the popular term " hydro- 

 phobia" arose from the reluctance of the diseased to take water be- 

 cause of painful spasms brought on by the attempt. 



The infectious nature of rabies seems to have been first demon- 

 strated by Gal tier.* Pasteur, Chamberland and Rouxf continued 

 the investigation and found that in animals that die of rabies the 

 salivary glands, pancreas and the nervous system contain the 

 infection, and are more appropriate for the experimental purposes 

 than the saliva, which is invariably contaminated with accidental 

 pathogenic bacteria. 



The introduction of a fragment of the medulla oblongata of a dog 

 dead of rabies beneath the dura mater of a rabbit causes the de- 

 velopment of typical rabies in the rabbit in about six days. 



Specific Organism.— It is not yet generally conceded that the 

 pathogenic micro-organism of rabies has been discovered, though there 

 is continually accumulating evidence in favor of the "bodies of 

 Negri."t Believing that the evidence at hand is strongly in favor 



* "Compte-rendu de I'Acad. des Sciences de Paris," 1S79, Lxxxix, 444. 

 Tlmd., 1881, xcii, 159. 



I Zeitschrift fiir Hygiene," 1903, xLHi, 507; XLiv, 520; 1909, lxii, 421 



363 



