THE TYPHOID FLY, OR HOUSE FLY. 27 



than it has hitherto assumed. Perhaps even under city conditions 

 it must assume third rank — next to water and milk.** 



It is not alone as a carrier of typhoid that this fly is to be feared. 

 In the same way it may carry nearly all the intestinal diseases. It is 

 a prime agent in the spreading of summer dysentery, and in this w^ay 

 is unquestionably responsible for the death of many children in sum- 

 mer. One of the earliest accurate scientific studies of the agency of 

 insects in the transfer of human disease was in regard to flies as 

 spreaders of cholera. The belief in this agency long preceded its 

 actual proof. Dr. G. E. Nicholas, in the London Lancet, Volume II, 

 1873, page 724, is quoted by Nuttall as writing as follows regarding 

 the cholera prevailing at Malta in 1849: " M}' first impression of the 

 possibility of the transfer of the disease by flies was derived from the 

 observation of the manner in which these voracious creatures, present 

 in great numbers, and having equal access to the dejections and food 

 of patients, gorged themselves indiscriminately and then disgorged 

 themselves on the food and drinking utensils. In 1850 the Superb^ 

 in common wiUi the rest of the Mediterranean squadron, 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 without com- 

 municating with the shore, the flies returned in greater force, and the 

 cholera also with increased violence. After more cruising at sea, the 

 flies disappeared gradually with the subsidence of the disease." 



Accurate scientific bacteriological observations by Tizzoni and 

 Cattani in 1886 showed definitely active cholera organisms in the 

 dejecta of flies caught in the cholera wards in Bologna, Italy. These 

 observations were subsequently verified and extended by Simonds, 

 Offelmann, Macrae, and others. 



With tropical dysentery and other enteric diseases practically the 

 same conditions exist. In a report by Daniel D. Jackson to the 

 committee on pollution, of the Merchants' Association in New York, 

 published in December, 1907, the results of numerous observations 

 upon the relation of flies to intestinal diseases are published, and the 

 relation of deaths from intestinal diseases in New York City to the 



" Dr. John R. Mohler, of the Bureau of Animal Industry, U. S. Department 

 of Agriculture, informs the writer that investigations made in his office show 

 that typhoid bacilli will live in butter under common market conditions for 151 

 days and still be able to grow when transferred to suitable conditions. In 

 milk under market conditions they retain active motility for 20 days, after 

 wliich time there is a gradual lessening in numbers until, on the forty-third day 

 of the test, they disappear from view. At certain seasons, of the year large num- 

 bers of flies collect upon the vats in which milk and cream are being stored 

 in dairies and creameries. Many of the flies fall in, their bodies being strained 

 out when the cream is sent to the churn. If any of these flies carry typhoid 

 bacilli these are washed off by the milk and remain in the butter or cheese 

 made from it. Thus the eating of butter contaminated in this way may account 

 for very many cases of typhoid fever the cause of which can not be otherwise 

 traced. 



