MORTALITY RATES 277 



of skin eruption and desquamation commonly present, and possibly 

 to the fact that the poisonous properties of the milk are to a certain 

 extent eliminated from the system by the vomiting and purging. 

 Every clinical sign which has been noted leads to the conclusion 

 that the disease as conveyed by milk is frequently mild, and there- 

 fore has both a small mortality and no tendency to spread by con- 

 tact. There is one other point deserving of mention. Sir George 

 Buchanan noticed, in a scarlet fever epidemic with which he had 

 to deal, that in persons who had had scarlet fever at some previous 

 time, and who drank the implicated milk, almost the only symptom 

 of ill-health which they presented was a sore throat There was 

 no rash, no vomiting, no pyrexia, although other members of 

 the family under precisely similar circumstances suffered from 

 typical scarlet fever. Many other workers have confirmed this 

 observation. 



In outbreaks of diphtheria due to milk, the disease appears to 

 take its ordinary course, except that it is less severe in most cases, 

 and less contagious. Accompanying such outbreaks there is not 

 infrequently an epidemic of " ordinary sore throat." 



Enteric fever does not show any peculiar modifications except, 

 again, these two of mildness and non-contagiousness. Multiple 

 cases occur simultaneously or in quick succession. One investigator 

 holds that in this disease, when conveyed by milk, adult and 

 elderly persons are attacked earlier and somewhat more severely 

 than children. But this observation has not been confirmed. 



5. Mortality Rate in Milk-borne Disease 



Finally, a note may be added respecting the mortality rates in 

 outbreaks spread by means of infected milk. Unfortunately, out of 

 some 260 records of epidemics the particulars of which we have 

 studied and which we consider authentic, only a small number 

 contain particulars as to deaths. If there were no deaths it should 

 be so stated, and in each epidemic investigated it is important to 

 record the fatalities. In the records of the outbreaks of scarlet 

 fever, in particular, these facts are often absent The highest 

 mortality rate we have come across in scarlet fever was 23-5 per 

 cent; the lowest nil. The average works out at about 12 per 

 cent In outbreaks of milk-borne typhoid the highest was 25-7, 

 and the lowest 7iil. The average of such outbreaks is about 1 1 per 

 cent Diphtheria works out at a higher fatality than the other 

 two diseases. The highest mortality percentage which we have 



