250 MILK AND ITS HYGIENIC RELATIONS 



The investigation of samples of cream obtained in the open 

 market showed the presence of virulent streptococci. The cream 

 used was stated to have been pasteurised by the 'flash method.' 1 



B. Tubercle Bacilli in Milk. The literature upon tuberculosis 

 in cattle, and in milk, and its relationship to disease can only be 

 described as voluminous, and any detailed consideration of the 

 subject would be outside the scope of the present work. It is 

 proposed to present only such aspects of the question as appear to 

 be inseparably connected with any consideration of the hygienic 

 aspect of milk. The literature dealing with the regulations for 

 controlling tuberculosis in cattle, and with the clinical signs of 

 tuberculosis in cows will be entirely omitted. The points which 

 will be considered are (i) the presence of tubercle bacilli in milk, 

 with an attempt to show their relative prevalence in milk samples 

 and in milking cows, and (2) the connection between the presence 

 of the bacilli in milk and the health of children. 



i. The General Prevalence of Tubercle Bacilli in Milk Samples 

 in certain Large Cities. The incidence of tubercle bacilli in milk 

 samples has now been investigated in the milk supply of a number of 

 cities, and the results have been published. It is not necessary to 

 examine a large number of the results obtained in the course of such 

 enquiries, since the prevalence of bovine tuberculosis in one country 

 does not afford any guide as to the prevalence of tuberculosis in 

 another. Only a few enquiries will therefore be considered. 



The Medical Officer of Health of the London County Council has 

 reported upon the presence of tubercle bacilli in milk samples 

 which had been examined under the auspices of this Council. He 

 states that between the date of the coming into force of the 

 L.C.C. General Powers Act of 1907 and December 1913, 13,321 

 samples of milk forwarded from places outside the county had been 

 examined for the presence of tubercle bacilli. Of these, 1323 

 samples, or 9-9 percent., had been found to contain tubercle bacilli, 

 as shown by the inoculation of guinea-pigs. During the year 

 1913, 2900 samples had been examined. Of these the examination 

 of 2682 was complete at the time of writing his report, of which 

 251, or 9-3 per cent., had been shown to contain tubercle bacilli. 



The presence of tubercle bacilli has been investigated on several 

 occasions in the market milk of New York. In 1909 Hess found 

 the incidence of tubercle bacilli to be about 16 per cent, of all the 

 samples examined by him, and in 1912-13 Grand and Wilcox found 

 that 9 out of 78 samples of milk examined, or 11-5 per cent., 

 were positive. 



Eastwood, in his investigations on the American milk supply, 

 obtained figures relating to the number of infected cows in North 

 Wisconsin in the years 1905-8. Out of 23,351 cows tested with tuber- 

 culin, 781, or 3-5 per cent, of all investigated, showed a positive 

 reaction. These cows belonged to 1586 different herds, of which 

 1 For explanation see p. 229. 



