XVIII] PROPHYLAXIS 317 



by the tsetse-flies. The rapid spread of sleeping sickness in 

 Uganda was the result of the fishing habits of the natives. 

 Fishermen should be recommended to cultivate the soil or 

 raise stock, and regulations prohibiting fishing in fly infested 

 regions should be enforced. Brumpt has suggested that the 

 natives who live on fish might be persuaded to grow vegetables 

 by importing dried sea fish in exchange for their vegetable 

 produce. Rubber collecting in palp alls areas should also be 

 abandoned and there is little doubt that the prevalence of 

 sleeping sickness in the Congo is largely due to this occupation. 



During the heat of the day all fly areas should be avoided 

 as the insects are especially active during these hours. Any 

 visits to the water that may be necessary should be made 

 either in the early morning or late evening. 



Whenever possible roads should be selected that do not 

 traverse fly areas, and when travelling fly-infested ferries and 

 fords should be avoided. If caravans are obliged to cross 

 such rivers at hours when the fly is active, they should not 

 be allowed to halt within a distance of at least 100 yards 

 of the water. In the construction of railways, fly areas might 

 also be avoided, for there is a great danger of these insects 

 being carried very considerable distances in the carriages of 

 trains. When trains have to travel through infested regions 

 the carriages and trucks should be protected with wire gauze ; 

 similarly, steamers that ply on fly-infested lakes or rivers 

 should have some portion of the upper deck protected. The 

 protective effect of clothing is well known and the comparative 

 immunity of Europeans and native chiefs is mainly due to their 

 practice of wearing clothes. The peasants who go about for 

 the most part naked are particularly liable to the bites of the 

 flies, and therefore they should be instructed as to the protective 

 effect of clothes. Europeans when travelling through infested 

 regions should take great care to protect their legs and arms, 

 and if the flies are numerous it is advisable to wear both veils 

 and gloves. It is possible that some substance may be found 

 which will be repellent to the fly and when rubbed on the skin 

 will keep it away, but up to the present no satisfactory repellent 

 has been discovered. 



