ACUTE INFECTIOUS DISEASES 85 



menced at the very next house he supplied, and continued with 

 considerable frequency along his route. After adding the X. 

 milk 16 houses were supplied and 8 were attacked (50 per 

 cent), while 22 cases resulted. 



In all, out of 244 cases, 234 (95-9 per cent) were supplied 

 with the infected milk. 



Dr. Davies made careful investigations as to the precise 

 source of the infection of the X. milk. It was found that at 

 the X. farm a stream known as the " Ashton Brook " flowed 

 through the farm and close to the farm buildings. By the 

 side of this stream, at a distance of only a few feet from it, 

 was a pump drawing water from a shallow well, and used for 

 all purposes of domestic or dairy use. The analytical data 

 showed that the pump-water was probably supplied from the 

 stream, and, as Davies remarks, " The conditions at the farm 

 were such that, given specific pollution of the brook, similar 

 infection of the pump-water was bound to occur, and the use 

 of this for any dairy purposes was evidently fraught with the 

 gravest danger." Inspection of the course of the Ashton Brook 

 showed that it formed practically the main sewer of the 

 straggling village of Long Ashton, which extends for a distance 

 of a mile or more along the main road. 



It was possible to go further and find the probable cause 

 of the outbreak. A farm labourer was found who had suffered 

 from an illness of two weeks' duration in September, whose 

 blood, examined subsequently, gave a positive Widal reaction, 

 and who had, therefore, almost certainly had an attack of 

 typhoid fever. The man worked where he could have polluted 

 the brook, while the dates of the cases forming the outbreak 

 showed that the milk was probably infected between the middle 

 and the end of September. He was the probable cause of the 

 specific brook contamination, and, through this water, of the 

 milk. 



It has been suggested that milk-borne outbreaks of typhoid 

 fever might be caused from the cows drinking water con- 

 taminated with typhoid bacilli, the bacilli being excreted into 

 the milk. In the light of present-day knowledge this source 

 of infection may be dismissed as non-existent. It is a quite 

 possible source of infection that cows standing to drink in 

 sewage -polluted water may contaminate their udders with 



