MAMMALS AS DISEASE CARRIERS IOI 



fly. Malta fever is spread by the milk of goats and other diseases by the 

 milk of cows. These are but a few of many instances that might be 

 mentioned of lower mammals that are carriers or hosts of diseases that 

 attack human beings. Many are already known, and the investigation 

 of this important and interesting subject is still in its infancy. Carrion- 

 feeders, such as coyotes, are especially likely to spread diseases of 

 livestock, but there is not as yet at hand as much definite evidence on 

 that subject as is desirable. It seems almost needless to mention the 

 obvious cases of transmission of disease from one mammal to another 

 of the same species, this being the most common type of carrier. Rats 

 and mice, running about in all sorts of places and "tracking" filth of 

 various-kinds over stores of human food, are potential carriers of many 

 serious diseases, which adds another to the reasons for their control by 

 rigorous methods. 



