DISSEMINATION OF YAWS IJY FLIES 281 



in the years from 1809-1815, published in Philadelphia in 1911 in 

 which this author says, in reference to yaws : " This horrible dis- 

 order is contracted by inhabiting the same room with a patient 

 and bv inoculation ; this is effected by means of a small fly, from 

 which every precaution is often of no avail. Great numbers of the 

 insects of this species appear in the morning, but they are not 

 so much seen when the sun is powerful. If one of them chances 

 to settle upon the corner of the eye or mouth, or upon the most 

 trifling scratch, it is enough to inoculate the hohas, if the insect 

 comes from a person who labours with the disease." In reference 

 to these two statements, as in many others where the word " flies " 

 is used, it may not be M. domestica to which the authors refer, in 

 fact the statement that the flies " are not so much seen when the 

 sun is powerful " militates against the idea, although it does not 

 in the least diminish the possibility of their being active agents in 

 the dissemination of infected matter. 



Other observers adduce similar evidence. Wilson (1868) states 

 that in the West Indies there is a prevalent belief that flies convey 

 the disease from one person to another. Two cases are reported 

 by Hirsch (1896) for which he believed flies were responsible. 

 Both patients were living among Fijian children who were affected 

 with the disease. The necessary raw places for the reception of 

 the infection were present, one patient having an uncovered ulcer 

 and the other sores on his feet, both of which exposed surfaces 

 would attract flies. Cadet (1897) also points out that skin lesions 

 such as ulcers, the bites of insects or other animals, scratches, etc., 

 are necessary for infection which may take place and through 

 direct contact of infected clothes or by means of flies carrying 

 the diseased secretions on their legs. 



Experimental evidence is brought forward by Castellani (1907). 

 He allowed M. domestica to feed upon infected matter obtained by 

 scraping slightly ulcerated papules. They were also fed upon the 

 semi-ulcerated papules on the skin of three yaw patients. In both 

 cases Spirochaeta pertenuis, the causative organism of this disease, 

 was found in microscopic preparations made from the mouth parts 

 and legs of the flies. Monkeys were also infected with the disease 

 by allowing specimens of M. domestica which had been fed as in 

 the previous cases to come in contact with lesions made on the 



