276 PATHOGENIC BACTERIA IN MILK 



drags over a longer period of time, but is characterised by the 

 constantly recurring cases following on at the incubation period. 

 In milk epidemics the multiple cases occur at once and simultane- 

 ously, and to a much lesser degree are they due to contact Indeed, 

 it is interesting to notice that many milk-borne diseases do not 

 appear to spread, even at a later date, by contact. As a rule, 

 they disappear as soon as the exciting cause is removed. We 

 have noticed repeatedly how marked and clearly defined is this 

 feature of multiple cases occurring early on in the history of an 

 outbreak, and we think it is one of the most important signs 

 of milk conveyance. 



4. Clinical Characters of Milk-borne Disease 



As we have already seen in passing, milk-borne disease, as a 

 rule, does not carry with it a heavy fatality rate. The outbreaks 

 are, as a rule, mild from the point of view of clinical signs and 

 symptoms, and also from that of mortality. The points observed 

 by various investigators may be very briefly stated in relation to 

 the three chief diseases conveyed by this channel. 



Scarlet Fever in not a few milk-epidemics has shown certain 

 modifications of a more or less marked character. The disease is 

 generally mild, and simultaneously with an outbreak of the specific 

 disease due to milk, there will not infrequently be found a large 

 number of " ordinary sore throats." Even in the scarlatinal cases 

 the disease has a tendency to remain localised to the throat 

 (Power). The rash may be evanescent, and the desquamation is 

 scanty (Parsons). There is also a marked absence of post- 

 scarlatinal nephritis or any other kidney complication (Parsons, 

 Buchanan, and others). A characteristic which has been frequently 

 noted, and is readily to be understood, is the frequency of vomiting 

 and diarrhoea, rather particularl)' at the commencement of the 

 disease (the Fallowfield epidemic, 1879, is an illustration). These 

 signs of alimentary irritation or poisoning have been observed by 

 various authorities. It is more than possible that they are due to 

 poisonous organismal products contained in the milk. On more 

 than one occasion they have led to an appearance of intoxication 

 rather than infection. Finally, there is a clinical feature, to which 

 reference has already been made, and which may bear a signifi- 

 cance not at first appreciated, namely, the comparative indis- 

 position of the disease to spread by contagion. This may be 

 attributable to the mildness of the disease, to the small amount 



