208 BACTERIA IN MILK AND MILK PRODUCTS 



on occasion to the water supply, and thus into milk and back again 

 to man. The virus does not always pass in the discharges to water 

 and milk, but may reach them by becoming dried dust. A small 

 pollution may in this way set up widespread disease. (For the 

 behaviour of the typhoid bacillus in soil, see pp. 145-150.) 



The most common way for milk to become infected by the 

 typhoid bacillus is through infected water. Such water may be 

 added to the milk by way of adulteration or by accident; or the 

 milk vessels may have been " cleansed " with polluted water (in 29 

 per cent, of milk -borne outbreaks according to Schuder). Another 

 source of infection of the milk is when persons suffering from a 

 mild attack of typhoid fever continue to work a dairy or otherwise 

 deal with milk, and this has proved a frequent means of infection. 

 Flies doubtless convey the germ of the disease not infrequently, as 

 was shown in the Spanish- American War of 1898 * and the Boer 

 War of 1900-1901.t 



Though the typhoid bacillus appears not to have the power of 

 rapid multiplication in milk, it has the faculty of existing in milk 

 for a considerable time (twenty days or longer) even when milk has 

 curdled or soured, and may thus infect milk products, such as butter 

 and cheese. But infection by milk products may be eliminated as 

 of too rare occurrence to deserve attention. The bacillus does not 

 coagulate milk like its ally the B. coli communis, which is a much 

 more frequent inhabitant of milk. It flourishes in milk at room 

 temperature and blood-heat, and does not produce acid or alter the 

 appearance of the milk. 



Several typical milk-borne outbreaks of typhoid fever may be 

 cited : — 



1. Infection from Personal Contact with Typhoid Patients. — At 

 Penrith, it appears that about the beginning of September, 1857, a 

 young servant girl, E. 0., returned home to Penrith from Liverpool 

 suffering fom typhoid fever. The family of which she was a 

 member consisted of father, mother, and five children, of whom she 

 was the eldest. The cottage in which they lived consisted of two 

 ill-ventilated and ill-lighted rooms, a kitchen or sitting-room, and a 

 bedroom opening out of it. The father possessed three cows, and 

 carried on a small milk business dealing with some fourteen 

 families. The mother milked the cows, and the milk was brought 

 into the kitchen, direct from the byre, and in due course dis- 

 tributed in tin measures amongst the customers. After her return 

 home the girl continued ill for about a fortnight, during which 

 period she "was nursed by her mother in the kitchen or common 



* Americam, War Department, Official Report, 1900. 



t Brit. Med. Jour., 1901, i,, p. 642 et seq. ; ibid., 1902, ii., pp. 936-941 (Firth 

 and Horrocks). 



