CHAPTEE XVI 



BACTERIAL DISEASES AFFECTING THE 

 NERVOUS SYSTEM 



Disease. Cause. 



Rabies ... ... Ultra- visible virus. 



Tetanus ... ... Bacillus tetani. 



Rabies. 



Fortunately rabies at present is an exotic disease in the 

 United Kingdom, but on the Continent, in India, America, 

 and Africa it is still very rampant. 



It is a specific infective disease due to a filterable virus, 

 affecting all the domesticated animals and several of those 

 of the wild species. The virus in its most virulent form is 

 found in the brain, the salivary glands, and the secretions 

 of the affected animal. The virus appears to pass along 

 the nerve fibres, and in this manner reach the brain and 

 the spinal cord, where it attacks the sensory cells causing 

 irritation and producing symptoms of great excitement, etc. 

 This condition of cellular irritability is followed by cellular 

 depression and organic degeneration, and death sooner or 

 later. 



There are certain diseases which simulate rabies in many 

 ways so far as the behaviour of an affected animal is con- 

 cerned, and it is most important that an accurate diagnosis 

 should be made. 



An animal having been bitten and showing cardinal 

 symptoms of rabies, however, would suggest little or no 

 difficulty in arriving at an accurate diagmosis. In some cases 



136 



