INCIDENCE ON MILK-DRINKERS 



2.67 



inhabiting houses of higher rental. But the incidence upon the 

 milk-drinkers in proportion to the amount of milk they consumed 

 is even more striking : — 



It is but rarely that it is practicable to draw up a return which 

 throws such a clear light upon the incidence in proportion to con- 

 sumption as this. But three years later (in 1889) Dr Parsons, who 

 was then investigating an epidemic of scarlatina at Upton and 

 Macclesfield, found opportunity for a similar return, which is as 

 follows : — 



Whilst there is some slight divergence in the percentages of 

 invaded houses and persons in these two tables, there is, taking 

 all things into consideration, a large measure of similarity. Such 

 figures must not be pressed too far, for it is evident that questions 

 of infection incidence are infinitely too complex to be reducible 

 accurately to mathematical proportion. In 1892 there was a 

 double outbreak of scarlet fever and sore throat in North-East 

 London (Upper Clapton), traceable to the milk supply, though the 

 exact method by which it became infected was not discovered. 



