CHAPTER XII 



BACTERIOLOGICAL EXAMINATION OF SHELLFISH 



Shellfish and Disease. The pollution of areas 

 devoted to the growing of shellfish and the consequent 

 pollution of the shellfish themselves is a matter of 

 much sanitary importance. Oysters, clams and mussels 

 are the shellfish commonly used as food, and since 

 they are likely to be eaten in an uncooked or partially 

 cooked condition, it is important to be assured as to 

 their character from the bacteriological standpoint. 

 In their normal habitats, in clean sea- water, or in river 

 estuaries free from pollution, shellfish are unquestionably 

 free from dangerous bacteria, although their feeding 

 habits make it probable that the types of bacteria 

 indigenous to the waters in which they are found might 

 be present in considerable numbers. With the pollu- 

 tion of streams by unpurified sewage the areas in which 

 oysters and clams develop may easily become infected 

 by organisms of intestinal types, and there is, therefore, 

 offered an easy means for the typhoid bacillus and other 

 pathogenes to pass from the sewage directly into the 

 intestinal tract of the consumer of the raw oysters or 

 clams. 



The history of this subject is well summarized by 

 Newlands and Ham (1910), from whose excellent report 

 the following paragraphs are adapted: 



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