AGE AND SEX INCIDENCE 



271 



scarlet fever outbreak in 1899^ in that city, suggested that a very 

 important guide in determining whether an outbreak of scarlet 

 fever is due to milk infection is to be found in the proportion of 

 persons above 15 years of age who are attacked, more especially if 

 of the male sex. In the Edinburgh outbreak it appears that four 

 adults aged 22, 26, 29, and 41 respectively, were attacked with scarlet 

 fever whilst residing in one block of a large institution, previously 

 free from scarlet fever and constantly kept under supervision. " The 

 chance of four adults becoming infected by ordinary' means," writes 

 Sir Henry Littlejohn, " and all developing the same disease on the 

 same day is very unlikely, but, on the other hand, the circumstance 

 is quite consistent with a poisonous dose of the infection having 

 been conveyed by milk." In this particular outbreak nineteen out 

 of forty-nine persons affected were above 1 5 years of age. 



In the 1901 outbreak of milk-borne scarlet fever in London 

 there were in Bethnal Green and Shoreditch a proportionately 

 large number of adults attacked. 



Hence, whilst age incidence may be useful as a provisional 

 indicator, it should be considered in relation to other circumstances, 

 and amongst these circumstances there are two in particular to 

 which due weight should be given, namely, the incidence upon the 

 persons living in the houses supplied with the implicated milk, and 

 the specific disease in question. The following tables are signi- 

 ficant in this relation. They refer to the outbreak of milk-borne 

 enteric fever in Clifton in 1897 '■' — 



1 Annual Report of the Medical Officer of Health of the City of Edinburgh, 

 1899, p. 40. 



* Transactions of the Epidemiological Society of London^ New Series, voL 

 xvii., 1897-98, pp. 93 and 96 (Dr D. S. Davies.) 



