MICROBIAL FOOD POISONING 493 



to severe gastro-intestinal irritation and convulsions. TBe remainder 

 of the fish is not poisonous. In some other fishes the sexual glands 

 are poisonous during the spawning season; others are provided with 

 special poison glands connected with protective spines or barbs. 

 These are examples of poisons natural to fish. Bacterial poisons are 

 likely to be formed in any kind of fish, given the suitable conditions, 

 and thus give rise to the kind of fish poisoning designated as botulism. 

 Cases of this kind have resulted from eating (spoiled) canned salmon 

 and sardines. Poisoning may also result from eating diseased fish, 

 the effects being due to poisons elaborated by the infecting bacteria 

 in the body of the fish before consumption. This appears to be a 

 rather common form of fish poisoning in Russia. B. paratyphosus has 

 been isolated from some poisonous fish, and certain toxicogenic an- 

 aerobes have been found in others. 



Poisoning with shell-fish is so well recognized that this form of 

 food is not customarily used at all during the warmer part of the year. 

 May to August inclusive, the months without an r in their names. 

 Shell-fish may serve as carriers of human infectious diseases, such as 

 typhoid fever; they may be poisonous on account of actual disease or 

 through serious contamination due to living in dirty water; or they 

 may be poisonous because of decomposition which has taken place 

 after removal from the water. According to the symptoms produced, 

 there appear to be at least three distinct varieties of shell-fish poi- 

 soning, one a purely gastro-intestinal disorder, the second an involve- 

 ment of the nervous system with itching skin eruption and convulsions, 

 and a third type resembhng very closely alcoholic intoxication. The 

 exact nature of the microbic agents concerned in these different types 

 of poisoning is unknown. It is pretty well established, however, that 

 the poisonous character of sheU-fish is due either to their Uving for 

 some time in dirty water, or to their too long preservation, especially 

 at high temperature, after removal from the water. 



Milk, ice-cream and cheese sometimes give rise to poisoning, and 

 although these instances are small in number in comparison with the 

 enormous amount of milk and milk products consumed, yet in the aggre- 

 gate they are numerous. That many human infections may be trans- 

 mitted by milk has already been pointed out. In the summer, milk is 

 undoubtedly a great factor in the infant morbidity and mortality, and 

 this poisonous action is largely due to bacterial changes in the milk. 



