3l8 SLEEPING SICKNESS [CH. 



The instruction of the natives and also Europeans, as to 

 the danger ot being bitten by tsetse-flies, should be carried 

 out systematically in all infected regions, for without the co- 

 operation of all persons it will be impossible to prevent the 

 occurrence of cases of sleeping sickness. 



It is most important that no person harbouring trypano- 

 somes in his blood should be allowed to travel from one 

 district to another. All sick persons should be segregated in 

 treatment camps, away from any species of tsetse-fly. The 

 employment of these segregation camps in Uganda has greatly 

 reduced the number of deaths from sleeping sickness, but unfor- 

 tunately such methods can never entirely eradicate the disease. 



It should be forbidden to recruit soldiers, carriers or 

 labourers in infected districts and bring them into any other 

 districts which contain fly areas. The importance of such pre- 

 ventive measui'es in the case of uninfected districts containing 

 G. palpalis is obvious, but the passage of persons harbouring 

 trypanosomes from one infected district to another should also 

 be avoided. Dr Bagshawe has called attention to the impor- 

 tance of this measure, for the strains of T, gambiense varv in 

 virulence. There is some evidence that m consequence of the 

 introduction of a virulent strain into a region where a mild 

 strain previously existed, a small endemic focus of sleeping 

 sickness has been succeeded by a great epidemic. It is also 

 possible that an epidemic which is gradually losing its virulence 

 and tending to die out may be kept alive by the introduction 

 of persons harbouring virulent trypanosomes in their blood. 



The only effective way of suppressing sleeping sickness is 

 by the extermination of the tsetse-fly, and, therefore, the most 

 important of all prophylactic measures are those directed 

 against the fly. In fact, the control of this disease is essentially 

 a problem for the entomologists. There are no doubt enormous 

 difficulties in the way of exterminating an insect ranging over 

 some millions of square miles of Tropical Africa, but the manner 

 in which Stegomyia and other mosquitoes are disappearing during 

 campaigns against yellow fever and malaria should make one 

 hesitate before considering such a task impossible. A complete 

 knowledge of the bionomics of G. palpalis, including its natural 



