286 THE DISSEMINATION OF OTHER DISEASES BY FLIES 



Wenyon (1911) has recently made a very thorough study of 

 oriental sore in Bagdad in which he investigated the possible 

 relation of house-flies to the disease. He found that house-flies 

 appeared to diminish in numbers to some extent during the hottest 

 part of the summer when the maximum shade temperature reached 

 110° F. Flies swarm about the faces of the children, especially 

 those having the sore. Such flies collected from the face of a 

 child suffering from an ulcerating type of sore are found to have 

 the intestine filled with the exudation of the sore in which the 

 parasites (Leishmania tropica) were readily found. Such a fly 

 feeding immediately afterwards upon some fresh abrasion of the 

 skin must certainly in a number of instances inoculate the sore 

 parasite. The parasite could not be found in the intestines of 

 Stomoxys feeding on the faces of children with sores. In infection 

 experiments with house-flies no evidence of the development of 

 the sore parasite could be found and they seemed to disappear 

 quickly. Wenyon concludes that the limited distribution of the 

 disease and the widespread prevalence of the house-fly would not 

 appear to confirm the view held by some authorities that the 

 house-fly is the normal carrier of the disease organism. 



In discussing tropical sore Nuttall and Jepson (1910) record 

 Seriziat's assertion that flies convey " Bouton de Biskra." In his 

 study of the disease at Biskra, Laveran (1880) found that from 

 September to October the slightest wound tends to become a sore. 

 He has seen it develop from small pimples and pustules and fi-om 

 wounds caused by burns or blisters. He believed that flies carried 

 the virus on their feet and proboscides and thus distributed 

 infection. 



There is no doubt that in tropical countries the organism of 

 the various types of sore can be mechanically transferred by flies 

 from the granulated areas to new wounds and thereby inoculate 

 the same. Its spread by flies would be governed by their 

 abundance, by the viability of the organism of the fly and the 

 opportunities for obtaining and distributing infection. In this 

 connection the observations of Patten' (1912) are of interest. 

 Referring to an idea entertained by some workers at one time 



- The Etiology of Kala-Azar, Nature, Vol. lxxxix. pp. 306—308, 1912. 



