DISSEMINATION OF LEPROSY BY FLIES 283 



deposited between the third and sixth days. The acid-proof 

 bacilli in the fly were not infective when injected into the sul)- 

 cutaneous tissue of the guinea-pig. 



Leboeuf (1912) has studied the dissemination of the leprous 

 bacillus by the house-fly. Flies (M. domestica) frequently settle 

 on leprous ulcers left exposed. Of twenty-three flies caught on 

 such ulcers knoAvn to contain many bacilli, nineteen were found to 

 contain the leprous bacillus in their intestines. The bacilli were 

 sometimes present in very large numbers and were excreted in the 

 faeces of the flies and showed no signs of degeneration even after 

 a day or more in the intestine of the fly. Bacilli Avere fouiul in 

 flies caught in the room and not directly on the ulcers but they 

 occurred less frequently in such cases. The author examined 

 twenty-three flies caught in his own house which was situated 

 about one hundred and fifty yards from the hospital reserved for 

 very advanced cases of leprosy, but in no case did he find the 

 leprous bacillus, which he takes as indicating that the range of 

 dissemination is not very gi-eat. While the foregoing experiments 

 would indicate that M. domestica is capable of disseminating the 

 bacillus, it apparently can be infected only from patients who 

 present open lesions or from infected discharges. B. leprae 

 was not found in twenty-nine flies caught in rooms of patients 

 with only nervous symptoms or with unbroken skin lesions. 

 Lebceuf concludes : (1) that M. domestica is capable of absorbing- 

 enormous quantities of the leprous bacillus ; (2) that the bacillus 

 is found in large quantities, apparently in perfect condition, in the 

 excrement of infected flies ; (3) that there does not appear to be 

 any multiplication of the bacillus within the fly, but the organism 

 does not seem to be degenerate ; (4) that it is possible that flies 

 passing from a leprous patient and depositing their excrement on 

 the nasal orifices, perhaps during sleep, or upon raw cutaneous 

 wounds of otherwise healthy persons living in the immediate 

 neighbourhood of leper patients, may disseminate the bacilli in 

 this way. 



Minett (1911) has also discussed the question as to the dis- 

 semination of leprous bacilli by flies. 



These experiments and observations, although conducted with 

 a comparatively small number of flies are, I think, sufficiently 



