FLIES AND OTHER HOUSEPIOLD INSECTS 9 



second place, it is possible that the typhoid bacillus may be carried 

 in the digestive organs of the fly and may be deposited with its 

 excrement. 



Dr Alice Hamilton in 1903, studying the part played by the 

 house fly in a recent epidemic of typhoid fever in Chicago which 

 could not be explained wholly by the water supply nor on the 

 grounds of poverty or ignorance of the inhabitants, captured flies 

 in undrained privies, on the fences of yards, on the walls of two 

 houses and in the room of a typhoid patient and used them to 

 inoculate 18 tubes, from five of which the typhoid bacillus was 

 isolated. She further found that many discharges from typhoid 

 patients were -left exposed in privies or yards, and concluded that 

 flies might be an important adjunct in the dissemination of this 

 infection. More recently, Dr Daniel D. Jackson investigating the 

 pollution of New York harbor in 1907 to 1909, found that by far 

 the greater number of cases occurred within a few blocks of the 

 water front, the outbreak being most severe in the immediate 

 vicinity of sewer outlets. He gives a series of charts showing an 

 almost exact coincidence between the abundance of house flies and 

 the occurrence of typhoid fever, when the dates are set back two 

 months to correspond to the time at which the disease was con- 

 tracted. He is of the opinion that most of the typhoid cases in 

 New York originate in local infections carried by flies. The bacilli 

 of typhoid fever were found by Ficker in the dejecta of house flies 

 23 days after feeding, while Hamer records the presence of this 

 bacillus in flies during a period of two weeks. It has recently been 

 found that flies produced from maggots living or developing in in- 

 fected material are capable of conveying disease even when not ex- 

 posed to subsequent infection. Most significant of all, it should be 

 noted that competent physicians in position to make extended obser- 

 vations upon this disease and the methods by which it may be dis- 

 seminated, are of the opinion that under certain conditions at least, 

 the fly is a very important factor. Epidemics spread by flies, accord- 

 ing to Dr Veeder, tend to follow the direction of prevailing warm 

 winds. He considers flies the chief medium of conveyance in vil- 

 lages and camps where shallow, open closets are used, thus afford- 

 ing the insects free access to infected material, and where it is pos- 

 sible to eliminate water and milk as the sources of infection. Drs 

 Sedgwick and Winslow, writing in 1903 state that " the three great 

 means for the transmission of typhoid fever are fingers, food and 

 flies/' the authors holding the last to be the most important. 



