134 TYPHOID FEVER 



house on May 3, 191 1. From this it may be concluded that 

 flies at this house had access to some specially infected matter, 

 and that the organisms were probably carried on their feet or 

 proboscis. Having definitely ascertained that a focus of infection 

 existed at Mrs P.'s house on May 3, 191 1, it is reasonable to 

 assume that this had existed previous to this date, and that 

 infected flies were the probable carriers of infection to case 1." 

 The distance " is less than 300 yards. It is possible that cases 

 2, 3, 4 and 5 were infected in a similar way from this house, but 

 the infection in cases 6, 7 and 8 was probably directly from other 

 cases." 



" It is interesting to note that the prevailing direction of the 

 wind during April, 191 1, was north-east." An east wind would 

 blow directly from Mrs P.'s house to the house of case i. 

 Unfortunately " Mrs P. refused to allow any investigation of 

 excreta or blood examination to be made." 



General Observations. 

 Temperate climates. 



The general evidence relating to the spread of typhoid fever 

 by flies in cities in temperate climates is at present far from 

 conclusive. The majority of the cases of the disease are 

 discovered early and are removed to hospital before the excreta 

 contain large numbers of the bacilli, and under any circumstances 

 the opportunities for flies to pick up infection, even from un- 

 recognized typhoid carriers, in well-sewered cities and towns are 

 small, since the bulk of the excreta is immediately passed into 

 the drains. It must be remembered, however, that even in 

 reasonably clean and well-sewered cities flies have some oppor- 

 tunities of infecting themselves. " The city of Washington 

 has the reputation of being perhaps the cleanest and best- 

 sewered city in the United States and yet it is possible any 

 summer morning to find human dejecta in alleyways and vacant 

 lots deposited there overnight by irresponsible persons, and in 

 the light of day swarming with flies. In the poor quarters of 

 the city uncared-for children of the indigent ease themselves 



