THE DOG AS A OAEKIBR OF PAEASITES AND DISEASE. 3 



muscular cysticercosis, or so-called "measles," in sheep; muscular 

 cysticercosis, or "measles," in reindeer; cysticercosis of the liver and 

 mesenteries in stock ; tapeworm in man, especially in children ; round- 

 worm in man; tongueworm in man and stock; and fleas and ticks 

 which transfer from the dog to man and which may in this way 

 transmit disease and parasites. The above list is sufficient to show 

 that the dog is of major importance as a carrier of parasites danger- 

 ous to man and domestic animals. An elaboration of the list follows. 



RABIES. 



It has been known for over 2,000 years that what are called mad 

 dogs, those affected with the disease termed rabies, hydrophobia, or 

 lyssa, could transmit this disease to stock and to man by biting them. 

 For 2,000 years the disease has been reported in sporadic and epidemic 

 outbreaks. It is now recognized as a widespread, acute, infectious dis- 

 ease of the central nervous system, characterized by extreme nervous 

 excitability. It is a disease which, if untreated, leads to a certain 

 death of the most horrible and agonizing sort. It owes its wide dis- 

 tribution and its very existence almost exclusively to the dog. The 

 disease may manifest itself in dogs or other animals under the form of 

 dumb rabies or furious rabies. In dogs there is commonly evidence of 

 depraved appetite, the dog eating sticks, leather, and stones, and the 

 finding of such things in the stomach is a suspicious indication of pos- 

 sible rabies. There is a partial or complete paralysis of the throat, and 

 the resultant difficulty in drinking is the basis of the erroneous idea 

 that the mad dog is afraid of water. As a matter of fact, such dogs 

 are often very eager for water but are unable to swallow it. The 

 disease seems to have some specific effect on the centers controlling 

 biting, the feature on which transmission of the disease depends, and 

 not only dogs but such animals as the horse show a tendency to bite 

 when affected with rabies. The disease is suspected of being due to a 

 parasitic protozoan, though as yet too little is known regarding this 

 to warrant a definite statement. An examination of the brain of 

 rabid animals shows certain cell inclusions known as Negri bodies 

 (fig. 1) , the nature of which is not at present well known. 



It has been pointed out in a previous publication ^ of the United 

 States Bureau of Animal Industry that rabies is becoming increas- 

 ingly prevalent in the United States. That publication cites the fact 

 that the New York Pasteur Institute had treated 1,608 cases of hy- 

 drophobia during the first 11 years of its existence, up to 1901. 

 The Chicago Pasteur Institute, established at about the same time as 



1 Babies and Its increasing prevalence. By George H. Hart. Bureau of Animal Indusr 

 try Circular 129. Washington, 1908. 



