CHAPTER XII 
DISEASES CAUSED BY PROTOZOA 
SUB ORDER MICROSPORIDIA 
RABIES 
Synonyms: Hydrophobia; canine madness; lyssa; rage; Toll- 
wut; Wutkrankheit. 
Characterization. Rabies is an acute infectious disease transmitted 
from animal to animal or from animal to man by the bite of the rabid 
individual or by direct inoculation. It is not known to be contracted 
or transmitted in any other manner. It is characterized by a long and 
variable period of incubation, followed by symptoms referable to the 
nervous system, lasting from one to ten days, and ending in paralysis 
and death, without recognizable gross anatomical changes. 
The dog is the animal most commonly affected, although all of the 
canine and feline races seem to suffer from rabies more than other 
species. All warm blooded animals appear to be susceptible. It isa 
serious disease in man, cattle, sheep, horses and swine. An explana- 
tion for its greater frequency among dogs is found in their tendency to 
bite. A very large percentage, in fact nearly all, of the cases in man 
and in the domesticated animals are caused by inoculation from the 
bites of rabid dogs. 
History. Rabies was described by Aristotle in the fourth century 
B.C. He wrote,““Dogs suffer from madness that puts them in a state 
of fury, and all the animals that they bite, when in this condition, 
become also attacked by rabies.” Cornelius Celsius, who lived in the 
first part of the Christian era, seems to have been the first to refer to 
human rabies and to employ the term ‘“‘hydrophobia.” It is referred 
to in the writings of Hippocrates. 
The transmission of the disease by wolves to man was recorded in 
1591. In 1803, and for a number of years following, it was epizoétic 
among foxes in Southern Germany and Switzerland. 
The first outbreak in this country was reported from Boston in 
1768. In 1770 and 1771 it was observed in dogs and foxes in the 
vicinity of Boston; in the year 1779 it appeared in Philadelphia and 
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