HUMAN DISEASES 535 



in 1936. Similar methods have been apphed in the recent outbreak 

 of sleeping sickness in the West Nile District of Uganda. 



Though it is convenient to divide the methods of control into 

 categories as above, in practice more than one method is usually 

 employed. Thus, in controlling the epidemic just mentioned 

 blocks of bush have been isolated by large clearings on the river- 

 side and flies are being eradicated from each by hand-catching 

 and trapping. This method gave excellent results when applied 

 by Symes to the tributaries of the Kiya River in Kenya (Symes 

 1936). In the French territories again, although efforts have been 

 concentrated mainly on cure by drugs, clearings of river banks, 

 etc. are made in suitable conditions. In the Anglo-Egyptian 

 Sudan, also, the Government has organized sleeping sickness cam- 

 paigns in recent years, whereby the disease is claimed to have been 

 practically eradicated from the Mongalla and Bahr-el-Ghazal 

 provinces. The measures adopted have consisted of cutting bush 

 along roads and stream^s, concentrating the population on the 

 cleared roadsides, long quarantine for suspected cases, and the 

 establishment of sleeping sickness settlements for treatment. 



PLAGUE 



Plague is firmly established in parts of Africa and may spread 

 to unaffected areas, with very serious results, unless strict precau- 

 tions are taken. The main centres are in South Africa, where it 

 appeared first in 1899 through infected rats escaping from ships. 

 East Africa, especially Uganda, where it was probably endemic 

 for a long period before European occupation, and West Africa, 

 where several importations have been made at the harbours. For- 

 tunately African conditions do not favour the contagious pneu- 

 monic form of the disease, but there are certain instances on record 

 where pneumonic plague has occurred and has not been recog- 

 nized until the contagion has spread, with fatal results. The mor- 

 tality rate of bubonic plague amongst Africans has varied between 

 25 per cent and 75 per cent of cases in various epidemics. 



The fullest recent description of plague in Africa is by Ricardo 



Jorge (1935a), who has also summarized the ancient and modern 



epidemics (1933) and given an account of the disease in Angola 



(1935b). The whole problem received attention at the Pan- 



