276 THE DISSEMINATIOX OF OTHER DISEASES BY FLIES 



way the infectious discharge is carried on the legs and proboscides 

 of the flies to the healthy children. 



Abel (1899) quotes the statements of Howe (1888) to the 

 effect that the number of cases increases rapidly from the moment 

 when flies are present in large numbers. Eye trouble occurs in the 

 same places when flies are numerous, e.g. the delta of the Nile ; in 

 the desert where there are few flies there are also few cases' of 

 illness. Natives and especially children are remarkably indifferent 

 to the attacks of flies, they allow the flies to settle in crowds about 

 their eyes, sucking the secretions, and never think of driving them 

 away. It is of interest to note that Howe states that an exami- 

 nation of the flies captured on diseased eyes revealed bacteria on 

 their feet which were similar to those found in the conjunctival 

 secretion. Howard (1911), whose attention was called by Howe 

 to these facts, sent to Egj^pt for specimens of the flies commonly 

 swarming about the eyes of ophthalmic patients which on exami- 

 nation proved to be M. domestica. I have also received specimens 

 from Egypt. 



Dr Andrew Balfour, formerly of the Gordon College, Khartoum, 

 in a letter to me, says that the Koch-Weeks bacillus is generally 

 recognised as being the exciting cause of Eg}^ptian ophthalmia. 

 He says, " Ophthalmia is not nearly so common in the Sudan as in 

 Egypt, nor are flies so numerous ; doubtless the two facts are asso- 

 ciated." Dr MacCallan, of the Egyptian Department of Public 

 Health, in answer to my inquiries, says that acute ophthalmias 

 are more liable to transmission by flies than trachoma. In his 

 opinion the spread of the latter is, to a comparatively small extent, 

 through the agency of flies, but it is mainly effected by direct 

 contact of the fingers, clothes, etc. 



The Koch-Weeks bacillus was first seen by Koch (1888) in 

 Egypt in cases of acute catarrhal ophthalmia. He found that two 

 distinct diseases were referred to under that name ; in the severe 

 purulent form he found diplococci, which he identified as very 

 pr(jbably Gonococci ; in the more catarrhal form he found small 

 bacilli in the pus corpuscles. He ascribed the propagation of the 

 disease to flies, which were often seen covering the faces of 

 children. Axenfeld (1908) states that " almost the only organisms 

 occurring in acute epidemics of catarrhal conjunctivitis are the 



