SCARLET FEVER OUTBREAK AT BRISTOL 381 



" In the aggregate we find up to i8th December, the close of the 

 outbreak : — 



On regular milk rounds .... 

 On regular rounds after 17th October . 

 Obtaining casual supplies from shop to which 



X milk was returned 

 Obtaining milk from shop on low-level round 



supplied with X milk 



Houses attacked obtaining milk from dairymen 

 not known to obtain infected supplies 



98 244." 



Dr Davies found the same methods of inquiry and statement 

 applicable in tracing the distribution of milk-carried scarlet fever 

 in an outbreak in Clifton in 1900. He writes : — ^ 



" The graphic method, which I first used in connection with the 

 outbreak of milk-carried enteric fever which occurred in Clifton in 

 1897, is here applied to a similar outbreak of milk-carried scarlet 

 fever. 



" The dairj' farm X is regarded as the source of infection. On 

 this farm at the time of the outbreak a boy who had access to the 

 milk vessels was suffering from an unrecognised illness which was 

 compatible with a mild (ambulant) attack of scarlet fever. The 

 veterinary surgeon found no evidence of disease among the cows, 

 and no other persons connected with the dairy farm showed signs 

 of illness. 



" The dair)^ farm X supplied milk to two Clifton distributors Y 

 and Z, and also distributed milk in the city direct from the farm ; 

 no other retailers obtained any milk from X. 



" These three distributors receiving milk supplied 269 houses, 

 ^of which 42 were attacked, furnishing 66 cases ; that is, one in 

 [every 64 houses was attacked. During the same period 85 other 

 [distributors not receiving X milk supplied 6922 houses ; and 9 

 cases occurred in as many houses, that is, i in every 769 houses 

 [was attacked, an incidence not indicating any unusual prevalence of 

 [scarlet fever in a large city. (Clifton has a population of 47,301. 

 I It is a registration sub-district of Bristol, which has a population 



" >f 324.973-) 



" Y obtained a part of his milk from a dairy farm A, but as A 

 |also supplied the retailers D and E, whose rounds were absolutely 

 ifree from scarlet fever, this farm is at once cleared from any 

 [suspicion. 



" Z also obtained some of his supply from farmers B and C ; but 



* Jour, of HygieTie^ 1901, vol. i., p. 388. 



