MOSQUITO WORK IN KHAETOUM AND IN THE ANGLO-EGYPTIAN SUDAN GENERALLY 21 



breeding in some of them. The larvse were destroyed wherever found, and the cases came 

 to an end. At no time were adult winged Anophelines found, but these must have e.xisted 

 in small numbers and undoubtedly caused the limited epidemic. 



In the future the desert land round both Khartoum and Khartoum North will, no doubt, 

 be irrigated. Herein lies a great danger to the health of the community, and one would 

 strongly advocate the preservation of a so-called " dry zone " behind both parts of the town. Necessity for 

 It should be at least one mile in width, that is to say, a mile of perfectly bare dry land, "dry zones" 

 a sandy stretch, wind-swept, and affording no shelter to mosquitoes, should be left between 

 the farthest likely extension of the town and the irrigated area. The necessity for such dry 

 zones has been strongly urged in India, especially at Madras,* while in Italy their establish- 

 ment is enforced by law. As is pointed out by Major King, it must ever be a case of asking, 

 " Is the game worth the candle ? " Personally I think it is — at least, as far as Khartoum is 

 concerned — while a somewhat modified scheme might be adopted for Khartoum North, where 

 admittedly the difficulties are greater. I have heard it said that the mosquitoes are preferable 

 to dust, but such dry zones would never be productive of much dust, and surely none could 

 prefer mosquitoes plus malaria, and possibly plus dengue, to the small amount of irritating 

 and annoying dust derived from such dry strips. Of course, a great deal will depend on the 

 type of irrigation employed. 



One has read with much interest Professor Ross's addressf on the subject of " The logical 

 basis of tjie sanitary policy of mosquito reduction." I believe that if one had time to 

 devote to it, the matter could be studied excellently well in Khartoum. Conditions are 

 specialised and simple, the area to be exploited is limited, so are the species of mosquitoes to 

 be studied. I have had no leisure to go fully into the matter, but I am inclined 

 to think that the results obtained here support certain of Professor Ross's conclusions, 

 and especially the one which states that " as a general rule for practical purposes, if 

 the area of operations be of any considerable size immigration will not very materially 

 affect the result." 



In Khartoum, however, it must not be forgotten that the subject is complicated by the 

 presence of mosquito-carrying steamers, boats and barges. Were it not for these, greater 

 success would have crowned the efforts at extinction, or rather reduction. 



It may be asked why operations conducted for so long a period have not resulted in the 

 almost total extinction of mosquitoes in Khartoum. The reasons are not far to seek. They 

 are to be found in the immigration already considered, in the smallness of the brigade and of Causes of want 

 the funds at our disposal, in the carelessness of householders and others as regards well success'^ '^ "^ 

 covers, the cleaning of zeers, and the repair of irrigation channels, and also to the imperfec- 

 tions to which all human labour is liable, and which are always more numerous when the 

 conditions are tropical and the workers coloured natives. There has to be constant vigilance, 

 and one must be prepared to make complaints and excite grievances. Memories must 

 be jogged and offenders punished if any success is to accrue. It is often wearying and 

 disheartening work, but it is worth doing, for the issues at stake are not trifling. Still we are 

 rid, and well rid, of the annoying Stegomyia, the dangerous Pyretophorns is kept in 

 abeyance, and Culex, the ubiquitous, has ceased to be a nuisance. 



The work is being conducted on much the same lines as hitherto. Native inspectors are 

 fined if pupae are found in water collections under their care. The amount of oil used per well 



* King. Indian Medical Gazette, June, 1905, Vol. XL., p. 201. 

 t Ronald Ross. Brit. Med, .Jour., May, 1905, Vol I., p. 1,025. 



