164 MANUAL OF BACTERIOLOGY. 



of secretion into the air, and that they may remain in sus- 

 pension some time. The pus-producing bacteria may be 

 present in dust. Infectious elements which happen to be 

 present in the air will usually be attached to particles of 

 dust. Wool-sorter's disease is a name sometimes applied 

 to anthrax in man when acquired by those engaged in the 

 work of handling wool, and in which the anthrax bacilli 

 or spores may be conveyed to the lungs in dust. 



The atmosphere in the vicinity of cases of the exanthem- 

 atous fevers at times probably contains the germs of these 

 diseases. 



Water is the usual medium for the transmission of the in- 

 fection in typhoid fever, and Asiatic cholera, and probably 

 all forms of dysentery. 



Milk from tuberculous cows may carry the bacilli of 

 tuberculosis; it is of most importance in the case of young 

 infants. Typhoid fever and cholera, and probably scarlet 

 fever and diphtheria are sometimes conveyed through the 

 medium of milk. Bacteria may reach the intestines in 

 uncooked food, fruit and vegetables. 



The Soil is of importance in connection with tetanus and 

 malignant edema, whose bacteria are frequently found in 

 soil. Bacillus aerogenes capsulatus may occur in the soil, 

 and may infect dirty wounds. The spores of anthrax bacilli 

 are present in the soil of certain localities, and may produce 

 anthrax in cattle. 



Flies and other insects and related animals are capable 

 of carrying the bacteria of disease. Under suitable condi- 

 tions flies play an important part in transporting the bac- 

 teria of cholera and typhoid fever from the excreta of these 

 diseases to food substances, which they may contaminate. 

 To what extent diseases are disseminated by fleas, bed- 

 bugs and similar creatures is still uncertain. 1 



'Nnttall, "Role of Insects, etc., in Disease," Johns Hopkins Hospit.-il 

 Reports, Vol. VIII., 1900. 



