POISONOUS CHEESE 251 



to be adopted for avoiding "diseases" of cheese and obtaining a 

 well-flavoured article which will keep. 



Finally, there is poisonoiis cheese which is of more importance to 

 the public health than all the other abnormal conditions of cheese 

 put together. In 1883 and 1884 there occurred in Michigan, U.S.A., 

 an outbreak of cheese-poisoning. Three hundred persons in all were 

 affected, and the illness was traced by Professor V. C. Vaughan to a 

 poisonous ptomaine present in the cheese, and to which he gave the 

 name tyro-toxicon. It is not improbable that this ptomaine is a 

 product of bacterial fermentation. It is one of a large class of 

 substances said to be formed by the action of bacteria upon nitro- 

 genous compounds. It is unstable, and easily destroyed by the 

 action of heat and moisture, and even by exposure to the air. Being 

 present in small quantities only, it has never been isolated in suffici- 

 ently large quantities to allow of its composition being definitely 

 determined. Tyro-toxicon has been proved to be a violent poison 

 both to man and the lower animals. A minute portion consumed 

 by a child produced sickness and diarrhoea in a manner almost 

 identical with cholera infantum (Vaughan). Similar symptoms were 

 obtained with cats and dogs. Vaughan found that three months are 

 required for the formation of tyro-toxicon in milk kept in tightly- 

 stoppered bottles; but under certain circumstances, and in the 

 presence of butyric fermentation in milk, the poison is produced in 

 about eight or ten days. Similar, and possibly identical, poisons 

 occasionally occur in cream, rancid butter and milk (lacto-toxicon and 

 diazo-benzol). They have the same poisonous effects. Vaughan has 

 isolated a microbe growing readily on ordinary culture media and 

 upon fruit and vegetables. This micro-organism, it is considered, 

 may be the agent producing tyro-toxicon, but the bacteriology of the 

 subject has not been worked out. 



The writer investigated a similar outbreak due to tyro-toxicon in 

 Dutch cheese in London in 1901.* Seventeen persons were affected. 

 The symptoms of illness in all these 17 cases occurred in from two 

 to eight hours after eating the cheese in question, which came from 

 the same consignment. Moreover, the symptoms were similar, 

 namely, epigastric pain, rigors, vomiting, diarrhoea, prostration, and 

 some fever. The degree of sickness does not appear to have 

 depended upon the amount of cheese eaten. There was no death 

 attributed to the poisoning, and in general the symptoms appear to 

 have passed off in the course of forty-eight hours. A short incuba- 

 tion period suggests that the poison was "available" in the cheese, 

 as a product of previous changes, possibly bacterial, set up therein. 

 A long incubation period between eating the food and symptoms of 

 poisoning would suggest that the persons affected had consumed, not 

 * Reporl on the Public Health of Finsbury, 1901, pp. 110-116. ^ 



