NON-BACTERIAL DISEASES 1 93 



Castellani (1907, p. 567) working in Ceylon thinks that yaws 

 is generally conveyed by actual contact, but under certain con- 

 ditions may be conveyed by flies and possibly by other insects. 

 "In my opinion, there can be no doubt that in certain cases insects 

 may carry the disease. It is very noticeable that flies eagerly 

 crowd on the open sores of yaws' patients. In the hospitals, as 

 soon as the dressings are removed the yaws' ulcerations become 

 covered with flies sucking with avidity the secretion, which they 

 may afterwards deposit in the same way on ordinary ulcers on 

 other people. Ants are also occasionally found on yaws' ulcera- 

 tions as well as on ordinary ulcers. 



" I may quote some experiments I have made to prove that 

 flies are instrumental in the dissemination of the disease. 



" Experiment I. Some scrapings were collected from slightly ulcerated papules of 

 a yaws' patient. The Sp. pertcnuis was present, together with various other thicker 

 spirochsetes [Sp. oblusa ; Sp. acuminata)., but no bacteria. The scrapings were 

 placed in a sterile Petri dish. Ten flies {Ahisca domesiica and allied species), caught 

 in the rooms of the Bacteriological Institute, were placed inside the Petri dish, and 

 left there for half an hour. They fed greedily on the material ; then their mouth 

 parts and legs were examined for spirpchsetes, extracts and films being made : in 

 nine flies the spirochcetes of the thicker type were found ; in two also the Sp. pertenuis. 

 As a control five flies were caught the same day, in the same room and examined at 

 once, with negative results as regards the presence of spirochetes. 



" Experimen-t II. Twenty flies were collected from the rooms of the Bacteriological 

 Institute. The buccal apparatus and legs of five were removed and examined by 

 making extracts and films : no spirochsetes of any kind were present. The other 

 15 flies were divided into several groups and placed on various semi-ulcerated papules 

 of three yaws' patients presenting the Sp. pertenuis, and spirochsetes of the thicker 

 type which are often found in semi-ulcerated lesions. The flies were kept in place by 

 covering the papules with a piece of gauze made to adhere to the skin by means 

 of collodion all round the margin. After two hours the mouth parts were removed, 

 extracts and films made and stained. Out of 15 flies so examined, in 14 it was 

 possible to detect the coarse spirochsetes, and in two, the Sp. pertenuis, as well as the 

 thicker ones. 



Transmission of Yazus to monkeys by means of flies 

 fed on Yaivs' material. 



" Experiment III. Thirty flies were fed in a sterile Petri dish for half an hour on 

 scrapings from non-ulcerated papules of a case of yaws, containing only the Sp. 

 pertenuis. Three Seinnopitheciis priamus and two Macacus pileattis were ^ then 

 infected in this way ; over the left eyebrow of each monkey, very numerous deep 

 scarifications were made ; then five flies, deprived of their wings, were applied to the 

 scarified spots and kept there by means of a piece of gauze smeared with collodion at 



G.-S. 13 



