XIII 

 MAMMALS AS DISEASE CARRIERS AND DISSEMINATORS 



It has long been known that certain species of mammals are active 

 agents in the dissemination of serious diseases that afflict the human 

 race, and that others may be. Sixteen years ago Jones 1 published a 

 list of mammal (and other animal) distributors, with the number and 

 names of the diseases each was known to disseminate, as follows 

 (omitting the names of the diseases and of all animals but the mam- 

 mals) : dog, 9; cow, 12; African antelopes, i ; cat, 5; horse, 5; sheep, 

 2 ; rat, 3 ; swine, 5 ; goat, 2. Other species are now known as dissemi- 

 nators and much more is known about methods of transmission. Re- 

 cently Hull, 2 with very much more information at his command, has 

 published a detailed account of diseases of domesticated mammals 

 which may be transmitted to man. 



The various diseases are transmitted in different ways, such as by 

 contact, by biting, through meat and milk. It will be noticed that most 

 of the animals listed by Jones are domesticated species. Naturally the 

 opportunities for animals that live about human habitations to carry 

 diseases to human beings are much greater than those of wild animals 

 that live far from homes and towns. Nevertheless some wild animals 

 are definitely known to be disseminators and probably many others are, 

 but of necessity much less is known about the wild animals than about 

 the domesticated animals under constant observation. 



The opportunities for pet dogs and cats to carry diseases are par- 

 ticularly numerous. They are often permitted to freely enter and leave 

 the sick-room, are handled by the patient and afterwards perchance 

 fondled by all the children of the neighborhood. The germs of many 

 diseases may readily be carried in the hairy coats of household pets 

 and thus spread through the community. Cats have greater opportuni- 

 ties to become carriers than have dogs, partly because they are more 

 decidedly household pets and are more intimately fondled. Every ef- 

 fort should be made to keep both away from patients suffering from 



1 Jones, On certain relations of the lower animals to human diseases, Science, 

 XLIV, 337-347, 1916. 



2 Hull, Diseases transmitted from animals to man. Springfield, Illinois, and Balti- 

 more, Maryland, 1930. 



