ACUTE INFECTIOUS DISEASES 



75 



Number of Houses supplied and invaded amongst Customers 

 of the Incriminated Milk. 



Age. This is very variable in the different epidemics. 

 Children are naturally greater milk consumers, but this 

 is sometimes counterbalanced by the fact that a considerably 

 greater proportion drink their milk boiled than do adults. 

 The habits as regards milk-boiling vary greatly, and, if the 

 outbreak chiefly affects the socially well-to-do, may quite alter 

 the age incidence and show a higher adult attack rate. 



Sex. The incidence is considerably higher on females 

 than on males, presumably because they are greater milk- 

 drinkers. For example, Davies in the 1897 typhoid epidemic 

 at Clifton found that 67 per cent of the total number 

 attacked were women. In the sore - throat outbreak at 

 Colchester the writer found that, out of 74 cases in which the 

 age and sex was recorded, 13 were adult males, 43 adult 

 females, and 18 children. The small proportion of children 

 was due to the good social position of the affected, and the 

 resulting high percentage of cases in which the milk was 

 boiled. 



4. The Milk Drinkers in particular Houses are attacked. 

 In many outbreaks careful individual inquiries will show that 

 those attacked are milk consumers, and those who do not 

 drink milk, or only when cooked, escape. This is valuable 

 corroborative evidence. 



A typical example which the writer personally observed 

 in the Colchester outbreak mentioned above is the following : l 

 "In one family the lady of the house, who drank a glass of 

 raw milk daily for lunch, was first attacked ; subsequently both 



1 Public Health, 1905, vol. xviii. p. 14. 



