PREVENTIVE MEDICINE 295 



to 30 others, of which 15 died. The disease lasted 15 to 30 days. 

 Monod and Velu* described outbreaks in Morocco affecting young 

 pigs rarely over 3 or 4 weeks' old. The virulence was variable, 

 the mortality being 5 to 80 per cent. 



RABIES. 



Rabies (hydrophobia, ly'ssa) is propagated in nature by 

 canine animals, though all warm-blooded animals, including man, 

 are susceptible. The cause is considered by most observers to be 

 an ultravisible virus, though others maintain that the so-called 

 Negri bodies, which are as a rule discoverable in various parts 

 of the nervous system, are protozoan in nature and are the actual 

 cause. The virus which is contained in the nervous system and 

 also in the saliva of animals affected is obligatory, the disease never 

 arising sporadically. Nocard and Roux discovered the saliva of 

 dogs to be infective at least 2 to 4 days before symptoms appear, 

 while Konradi states that the bites of rabid dogs are dangerous 

 8 days before the onset of symptoms, f Rabid animals of nearly 

 all species develop a marked tendency to bite, and transmission in 

 natural cases occurs in this way. Even animals which are naturally 

 docile, e.g., sheep, become very aggressive when attacked by the 

 disease. An interesting outbreak occurred in 1887 among the deer 

 in Richmond Park, and this same tendency was noted. The disease 

 existed in this country certainly as far back as the tenth century, 

 and was at one time of fairly frequent occurrence, as may be seen 

 from the following table : 



Year. No. of Cases. Year. No. of Cases. 



1889 312 1897 151 



1890 129 1898 17 



1891 79 1899 9 



1892 38 1900 6 



1895 672 1901 1 



1896 438 1902 13 



During the period 1848 to 1902, 1114 persons are stated to have 

 died of hydrophobia in Great Britain. $ With the exception of 

 one dog, which died while in quarantine in 1915, Great Britain was 

 free from the disease from 1903 to 1918, in which year the disease 

 was again introduced. 



* Trop. Vet. Bull, 1916, Vol. IV., p. 115. 



t Hutyra and Marek, Spec. Path., Vol. I., p. 468, Trans. 



t Annual Report, C.V.O., Bd. of Agric., 1903. 



