658 SCIENCE PROGRESS 



and is commoner than has been generally supposed in the 

 hinterlands corresponding to the above regions. On the Upper 

 and Lower Congo the disease has lately occurred as an epidemic, 

 and has been very widely fatal. 



Cook, in 1900, discovered that sleeping sickness existed in 

 Uganda; since then it has spread far, but has kept mainly 

 to the north shore of Lake Victoria Nyanza. The disease 

 apparently started in Usoga, spread west to Buddu and east 

 to Kisumu. Northward, a few cases have been recorded at 

 Kiadondo ; but the disease is unknown in some of the northern 

 provinces, in Unyoro, and round the Albert Lake and the Nile 

 districts. The centre of its virulence has been in Usoga and 

 Chagwe, round Entebbe, and in the islands close to the main- 

 land, from the Sese group westward to the Kavirondo islands 

 eastward. It is, apparently, not known in German East Africa 

 to the south and west of the lake, nor among the Nandi and 

 Masai tribes of British East Africa east of Kisumu. 



Previously to 1901, sleeping sickness had been recorded only 

 in West Africa. In that year a widespread epidemic occurred 

 in Uganda. It was confined to the lake shores, and was most 

 prevalent in low-lying areas, or in wooded districts near the 

 water. The people living in populous centres were almost, and 

 those on open grass plains quite, exempt from the disease. The 

 Soudanese living in Uganda remain practically free from sleeping 

 sickness. They live in large, well-laid-out villages, which are 

 kept cleared of vegetation, and are regularly cleaned and swept. 



Age has no influence on the disease. As regards occupation, 

 the poorest people working in the fields suffer most. Chiefs 

 and the better-class natives are less affected. Season and diet 

 cannot be found to have any influence in the causation of the 

 disease. 



Etiology. — Many different hypotheses have been brought 

 forward as to the origin of sleeping sickness. One theory was 

 that the disease arose from the distress in connection with 

 slavery. Other theories were — that it was a form of sunstroke, 

 a variety of beri-beri, a variety of malaria, or due to scrofula. 

 More recent theories are that the disease is a food-intoxication, 

 that it is due to animal parasites, or due to bacteria. 



Food-intoxication. — The theory has been put forward that 

 this malady is due to manioc poisoning, and analogous to the 

 disease pellagra, which is attributed to poisoning by maize. 



