198 UNIVERSITY OF WISCONSIN STUDIES 



should certainly be kept out of ice cream plants by every 

 possible method. It now seems evident also that a negative 

 Widal is by no means definite proof that a certain individual 

 is not a carrier. An epidemic in Brooklyn in 1914 was not 

 traced to its source, and in 1915 another epidemic in the 

 same section led to stool examinations of the employees of an 

 ice cream plant supplying most of the ice cream, with the re- 

 sult that a man who had been working in the factory in 1914 

 was found to be a carrier. A typhoid epidemic in California 23 

 was found to have been due to ice cream made by a woman 

 who had had typhoid 17 years before and who gave only 

 a partial Widal. This same ice cream also caused poisoning 

 in the persons consuming it and all but two of the persons 

 poisoned developed typhoid. A portion of the ingredients 

 was heated, then cooled and added to whipped cream, after 

 which the mix was allowed to stand from 6 :30 until 1 :00 

 o'clock without ice, before being made into ice cream. 



The presence of organisms producing disease in non-epi- 

 demic form is very likely to occur unless proper care and 

 handling are followed. 



If pathogenic organisms are present in ice cream, the low 

 temperatures to which they are subjected during the harden- 

 ing and holding process cannot be depended on to destroy 

 them. While there will likely be a falling oft* in the numbers 

 of living cells, low temperature cannot be counted on to make 

 the product safe. At the Iowa Agricultural Experiment 

 Station, 24 ice cream artificially infected with the tubercle 

 bacillus was found capable of producing tuberculosis in guinea 

 pigs after one month, which is as long as the tests were made, 

 this period being considerably longer than ice cream is likely 

 to be held under practical conditions. 



2 -' Letter from New York City Health Dept. 



23 Jr. Am. Med. Assn., April 21, 1917. 



24 Unpublished data. 



