152 MANUAL OF BACTERIOLOGY. 



from the milk of such cows may contain tubercle bacilli. The 

 proper manner for the States to deal with this problem, for it 

 is one that doubtless will fall to the individual States, has not 

 yet been determined. The cost of killing such a large number 

 of valua ble cows would be very great. Furthermore, it is by 

 no means certain that this procedure would eradicate the dis- 

 ease. The flesh of cattle also is capable of transmitting 

 tuberculosis, but is a less serious source of dangei: when beef 

 is thoroughly cooked. 



Epidemics of typhoid fever and cases of diphtheria have 

 been traced to milk; and no doubt cholera asiatica is conveyed 

 in this way in times of epidemic. 



Human milk often contains streptococcus epidermidis 

 albus, and not seldom the staphylococcus pyogenes aureus 

 under normal conditions. 



Scarlet fever is probably conveyed by milk, but as the organ- 

 ism causing this disease is not yet definitely known, it has not 

 yet been detected in milk. But there is apparently good clini- 

 cal evidence of this. 



Streptococci have been found quite frequently in milk sold 

 in the market.* Bacillus coli communis is very often present 

 in milk, but it is probably without significance unless it is 

 present in very large numbers when it is possible that it causes 

 injurious fermentative changes. Fermentative changes are 

 also caused by the presence of bacteria which are not in them- 

 selves the cause of disease, and these changes may render the 

 milk unfit for consumption or even poisonous. These altera- 

 tions may be evident to the senses, as the ordinary lactic acid 

 fermentation (souring of milk), or they may not. The charac- 

 ter of the alterations doubtless varies much with the tempera- 

 ture and with the character of the contaminating bacteria. 

 Summer temperatures of course favor decomposition and fer- 



*Reed and Ward. The Significance of the Presence of Streptococci in Market 

 Milk. American Medicine. February 14, 1903. 



