September 8, 1916] 



SCIENCE 



343 



the animal should not only show symp- 

 toms but should be rapidly fatal so as to 

 remove the source of danger as soon as pos- 

 sible. Malta fever is a very different dis- 

 ease to control because the goats so often 

 show no clinical symptoms. Also a chronic 

 disease in animals is a source of danger for 

 a long period of time whereas the acutely 

 fatal diseases terminate the danger quickly. 

 Chronic glanders in the horse as compared 

 with acute glanders illustrates well this 

 point. Furthermore by the death of the 

 animal in the rapidly fatal diseases usually 

 the more highly virulent and hence the 

 more dangerous strains of microbes are de- 

 stroyed at the same time. 



Usually the natural animal diseases 

 transmissible to man are deleterious to him. 

 Occasionally a natural animal disease has 

 been made to serve a good purpose by fur- 

 nishing a means for protective inoculation 

 in man. Cowpox is an example, the natu- 

 ral virus being continued in the cow and 

 then transferred artificially to man for 

 protective purposes against smallpox. The 

 Pasteur treatment in hydrophobia depends 

 on much the same principle, the virus be- 

 ing propagated however in another animal, 

 the rabbit, the spinal cord of which is then 

 artificially inoculated into man for preven- 

 tive purposes. 



As a result of the use of animal products 

 for protective and curative purposes in 

 medicine, there is produced at times the 

 condition of anaphylaxis known as "serum 

 disease. ' ' This reaction is so serious that it 

 may actually interfere with the use of 

 serums over long periods of time in the 

 treatment of chronic disease. The success 

 of serum therapy has so far been confined 

 largely to acute diseases which ordinarily 

 do not require long treatment, so that the 

 danger of anaphylactic shock has not in 

 this respect seriously restricted the use of 

 serums. In this connection might be men- 

 tioned the state of certain individuals who 



are hypersensitive perhaps naturally to the 

 odor of horses and when near the animal 

 manifest definite symptoms of an anaphy- 

 lactic character. 



Certain diseases common in animals and 

 man exist in which there is little or no evi- 

 dence that man is infected directly from 

 the animal. Actinomycosis is such a dis- 

 ease. It is doubtful if there is a case on 

 record in which man became directly in- 

 fected with the actinomyces through con- 

 tact with a diseased animal. Sporotricho- 

 sis likewise is common in horses and in 

 man, but there is but one or two cases where 

 direct infection occurred and this was 

 through the bite of a horse. In such dis- 

 eases the animals are dangerous not so much 

 through direct contact as through the gen- 

 eral dissemination of the microbes upon 

 soil, grass, fodder and various objects, 

 thereby greatly increasing the opportunity 

 for human infection in a variety of indirect 

 ways. 



While man receives a large number of 

 diseases from or through the lower ani- 

 mals, if we inquire into the reverse propo- 

 sition, we find that any one of the lower 

 animals though suffering on the whole from 

 many diseases, acquire relatively few from 

 other animals including man. The horse, 

 for example, receives rabies from dogs, and 

 occasionally anthrax from sheep and cows. 

 Tuberculosis hardly exists in this animal. 

 In the tropics it has its diseases carried by 

 flies and ticks though they apparently are 

 not as numerous as the human diseases so 

 transmitted. The cow appears to be some- 

 what more susceptible to diseases from other 

 species than is the horse but apparently not 

 as susceptible as man to such. The dog and 

 the other animals enumerated, all have a 

 host of their own diseases, relatively few 

 of which seem to depend on some other ani- 

 mal for their transmission. Exception 

 might be taken to this statement concern- 

 ing the lower animals. It may be that it 



