HUMAN DISEASES 533 



shores, and fresh cases of sleeping sickness have not occurred. In 

 such areas, however, there is always the potential danger that 

 some immigrant person with sleeping sickness may reinfect the 

 fly, thereby causing a new epidemic. It is important, therefore, 

 that the population should be separated from fly as much as 

 possible, and the usual policy is to allow reoccupation of lake shores 

 and other tsetse-infected areas only when the population is suf- 

 ficiently dense to maintain proper clearings. Food crops likely to 

 shelter fly in close proximity to tsetse-infected bush are prohibited. 



The bearing of such means of sleeping sickness control on the 

 improvement of agriculture is stressed by the measures which are 

 being introduced in Northern Nigeria to concentrate the popula- 

 tion, and introduce mixed farming [see Chapter XIII). Again, in 

 Tanganyika the control of infection by T. rhodesiense is coming to 

 depend mainly on settlement and reclamation schemes which have 

 been advocated especially by Maclean (1930) and the Conference 

 of East African Governors (1934b). 



The second method of control, involving efforts to reduce the 

 incidence of fly by clearings, traps, etc., has been discussed at 

 length in Chapter X. In chemotherapy, great progress has been 

 made recently in the use of the two drugs Germanin (Bayer 205) 

 and Tryparsamide, an arsenical preparation. Although the effects 

 vary with different species and strains of trypanosomes, in general 

 germanin is effective in the initial stages of the disease and trypar- 

 samide in the later, and for general application in stricken areas a 

 combined method of treatment has been applied with much suc- 

 cess. 



Curative methods have been especially developed in the French 

 and Belgian colonies, for which the system o^ equip es de prospection 

 et traitement has been described in Chapter XV. For the Camxroons, 

 where sleeping sickness has increased steadily during the past ten 

 years, some results have been given by Jamot (1930) and Millous 

 (1935). During the year from October 1933 to 1934, 546,000 

 natives were examined, of whom 61,800 had the disease, but only 

 3,300 of these remained carriers of trypanosomes after treatment. 

 The sleeping sickness work is combined with an attack on other 

 diseases and the collection of valuable demographic statistics. In 

 the Belgian Congo the state service has concentrated on sleeping 



