150 THE HOUSE FLY— DISEASE CARRIER 



Ainsworth concludes, **It seems to me that enteric pre- 

 vention naturally groups itself under five headings, 

 namely, ( i ) Isolation of the human carrier, failing 

 (2) elimination of the bacillus by means of some drug 

 as yet undiscovered; (3) rendering excreta innoxious 

 by disinfection, water carriage, and similar sanitary 

 measures; (4) the establishment of immunity; and (5) 

 the destruction of the go-between, to wit, the fly/* 



Cholera 



One of the earliest accurate scientific studies of the 

 agency of insects in the transfer of human diseases was 

 with regard to flies as spreaders of cholera. The be- 

 lief in this agency long preceded its actual proof. Dr. 

 George E. Nicholas (1873) is quoted by Nuttall as 

 writing as follows regarding the cholera prevailing at 

 Malta in 1849: 



"My first impression of the possibility of the trans- 

 fer of the disease by flies was derived from the observa- 

 tion of the manner in which these voracious creatures, 

 present in great numbers, and having equal access to 

 the dejections and food of the patients, gorged them- 

 selves indiscriminately and then disgorged themselves 

 on the food and drinking utensils. In 1850 the 'Superb,' 

 in common with the rest of the Mediterranean squad- 

 ron, was at sea for nearly six months; during the 

 greater part of the time she had cholera on board. On 

 putting to sea the flies were in great force; but after 

 a time the flies gradually disappeared, and the epidemic 

 slowly subsided. On going into Malta harbor, but 



