t$6 TYPHOID FEVER 



Tropical cliviates. 



Numerous workers have recorded their belief that flies play 

 ail important part in the dissemination of typhoid fever in 

 stations in the tropics. The observations of Faichnie (1909) and 

 of Cochrane (191 2) have already been quoted, and a few extracts 

 from other interesting reports will be sufficient to indicate the 

 observations on which this very general belief is founded. 

 Reports concerning Poona and Nasirabad in India, and Bermuda 

 have been chosen because they cover a series of years. 



Writing of Poona, Ainsworth (1909) says : 



"We find then, year by year, that in Poona and Kirkee 

 enteric fever begins in July, reaches its maximum in August, 

 maintains a high level in September, dies down in October, 

 and nearly disappears in November and December. The ad- 

 missions for the two months, August and September, are 

 considerably higher than those for all the other ten months put 

 together, and for the four months, July, August, September and 

 October, rather more than \.\\o and a half times greater than the 

 sum of the other eight months. This is a very striking fact, and 

 points unmistakably to a regularly recurrent cause. Now these 

 four months are the monsoon months, and at first it would seem 

 to afford proof positive that the germs are water-borne ; but, apart 

 from the fact that there is a pipe supply from a distant catch- 

 ment area, not very liable to contamination, and that analyses, 

 both chemical and bacteriological, exonerate the water, it is 

 practically certain that if water were the agent the first outburst 

 would follow the break of the monsoon in the average incubation 

 period, say fourteen days, and the maximum intensity would be 

 reached within the month, as the accumulated filth of the ante- 

 cedent dry days would be washed down by the first floods. But 

 this is not so, as reference to the annexed charts will show ; 

 on the contrary the monsoon breaks invariably in the middle of 

 June, and enteric does not become epidemic until August. But 

 heat and moisture, combined with suitable breeding media, will 

 for certainty produce flies. Unfortunately, I can only speak of 

 this one season, which local residents did not consider to be 

 a bad year for flies, yet in July, 1908, the flics were simply 



