84 MILK AND THE PUBLIC HEALTH CHAP. 



introduced by Davies l (M.O.H., Bristol) who investigated and 

 described the outbreak. 



The epidemic occurred in Clifton, Bristol, and was extensive, 

 the number of cases being 244. The evidence implicating 

 the milk supplied from a particular farm (Farm X.) is very 

 complete. Three particular supplies (X., Y., Z.) were found 

 to be implicated (see Chart). The milk from Farm X. was 

 met by the purveyor and distributed direct from the churn 

 to the customers without its going to any dairy. Any milk not 

 used on the round was, however, returned to the branch dairy, 

 and sold to casual customers. Before the 26th of September 

 (when the big schools reopened) the supply was sufficient to 

 serve two districts the low level and the high level but 

 after this date the supply was confined to the high-level 

 district. On these two rounds 56 houses were supplied and 

 31 were attacked (55 - 3 per cent), while 114 cases resulted, or 

 more than 2 cases per house. The inmates of these houses 

 numbered 453, so that 25'1 per cent were attacked. 



Milkman Y. started with a pure supply, but before entering 

 the city met the X. cart, and occasionally took a supple- 

 mentary supply from the churn consigned to Clifton. After 

 receiving this supplementary supply he supplied milk which 

 yielded 8 cases outside Clifton, and within the city supplied 

 40 houses, of which 18 were attacked (45 per cent); 48 cases 

 resulted from these 40 houses, or more than 1 case per house. 

 The inmates of these houses numbered 308, so that 15*5 per 

 cent were attacked. 



The other implicated supply, Z., was distributed in Clifton 

 on three rounds. Two of these rounds were entirely innocent 

 of cases, and the third round was, with one exception (a servant 

 who lived close to, and admits to frequently obtaining casual 

 supplies from, the branch dairy to which unused X. milk was 

 returned), also free from cases up to a certain point, but beyond 

 this point cases occurred with marked frequency (see Chart). 

 It was found by plotting the routes on a map that at the very 

 corner where this change from freedom to infection occurred, 

 Z.'s round met that of the X. supply, and Z. admitted that he 

 was in the habit, when running short, of obtaining at this 

 point supplementary supplies from X. After this, cases com- 



1 Trans, of the Epidemiological Society of London, 1897-98, xvii. 78. 



