452 BIOLOGICAL AND SANITARY MATTERS. 



source of milk supply. As the tubercle bacillus is comparatively 

 easily destroyed by heat, pasteurisation of milk may be resorted 

 to ; keeping the milk for a quarter of an hour at 70 C. (162 F.) 

 practically will remove the source of infection. Another, but less 

 satisfactory method, is to mix the milk with that of healthy 

 cows and trust to Providence for the presence of sufficient lactic 

 acid organisms to destroy the tubercle bacilli ; even if they are 

 not destroyed, they are sometimes so diluted that they have no 

 toxic effect on healthy adults, though children and persons 

 weakened by disease or predisposed by heredity to consumption 

 may be affected. 



Other diseases pleuro-pneumonia, foot and mouth disease, 

 and scarlatina (or an analogous skin disease) may be derived 

 from the cattle. These are much less common than tuberculosis 

 and less insidious, as the symptoms can be detected with com- 

 parative ease in the cows. Practically speaking, tuberculosis is 

 the only disease which needs to be guarded against by systematic 

 veterinary inspection. 



Conveyance of Disease through Contamination of the 

 Milk. The labours of the late Ernest Hart in collecting statis- 

 tics have shown conclusively that typhoid, cholera, scarlet fever, 

 and diphtheria can be conveyed through milk. 



There are practically two causes : (1) the occurrence of the 

 disease in the milkers and those handling the milk, and their 

 families ; and (2) the presence of the organisms to which the 

 malady is due in water used for " cleansing " the utensils or for 

 adulterating the milk. 



The epidemics of scarlet fever and diphtheria which have been 

 spread through milk have almost all been due to the milk being 

 handled, shortly after milking, by those either affected with the 

 disease, or living in the same house with sufferers. The remedy 

 is, of course, obvious ; a rule should be made in every dairy that 

 all workers who feel unwell should absent themselves from their 

 work, and pay an immediate visit to a medical man ; if any 

 members of their families be ill, medical advice should be simi- 

 larly obtained ; and if the disease be infectious, the worker 

 must at once be suspended from duty, and not allowed to- go 

 near the dairy. 



It is found in practice that this regulation can be carried out 



(1) By the employer providing for the services of a medical man. 



(2) By the payment of full wages to any worker who is suffering from 

 infectious disease, and suspended from duty. 



(3) By a distinct understanding that the breaking of the regulation by 

 a worker means instant dismissal without notice. 



Water - borne Diseases. Typhoid and cholera, which are 

 essentially water-borne diseases, have, in the majority of cases 



