42 



i^oEKE (W.), Sleeping- Sickness and Big Game. — MuntlL. May. 

 Chamh. Commerce, Liverpool, xii, uo. 1, Jan. 191oj pp. 4-9. 



lu this address the author reviews the general history of sleep- 

 ing sickness and the discovery that it can be transferred from man 

 to man by Glossina palpalis. In 1908 the disease was unknown 

 in Nyasaland, but in 1909 and 1910 a number of cases occurred 

 amongst Europeans and natives. The disease has also been found 

 in llhodesia. The investigations carried out by the author, Dr. 

 A. Kinghorn and Mr. L. Lloyd were made around Nawalia, 

 N.E. llhodesia, the site of an old Government station in the 

 Luangwa Valley, about 400 miles from the railway. Pack- 

 animals could not be used for the journey because, owing to the 

 presence of the tsetse-fly (G. morsitans), they quickly succumb 

 to trypanosomiasis; but antelopes of various kinds w^ere present 

 in the valley in enormous numbers. The author remarks incident- 

 ally that the old idea of suitable dress for travelling or hunting 

 in tropical Africa needs modification. In order to avoid the 

 attack of the tsetse-fly it is essential that as little skin as possible 

 should be exposed, and he recommends that a fly-switch made 

 from a zebra's tail should always be carried and used. Khaki 

 though an excellent colour from the hunter's point of view, 

 appears to attract tsetses in large numbers. The natives are more 

 liable to be bitten than Europeans owing to their wearing practi- 

 cally no clothes. 



In this district G. palpalis does not exist, but G. ■morsitans is 

 present in enormous numbers, and the investigators have been 

 able to prove that this fly is responsible for the spread of sleeping 

 sickness in man. Unlilvfi G. palj^alis, it is not limited to the 

 neighbourhood of rivers or lake shores, but is found all over the 

 country in enormous stretches, its distribution being quite inde- 

 pendent of water. This fact renders the removal of the popula- 

 tion from fly-centres impossible and greatly increases the 

 diflSculty of combating the disease. Another fact of great 

 practical importance was discovered, viz., that unless the atmos- 

 pheric temperature was fairly high the tsetse-fly does not become 

 infective after biting an infected animal. This Avas proved by 

 direct experiment in the intensely hot country of the Luangwa 

 Valley, where the investigators were able to transmit the poison 

 to healthy monkeys by means of flies which had been allowed to 

 bite sleeping sickness patients two or three weeks before. When 

 the experiments were repeated on the comparatively cold plateau 

 of the Congo-Zambesi watershed, the results were negative. Un- 

 fortunately at certain periods of the year the temperature of 

 localities over 4,500 feet above the sea is quite high enough to 

 allow of the complete development of the parasite in G. morsitans 

 and apparently they remain infected for a very considerable 

 period. 



The investigators satisfied themselves that the main reservoir of 

 trypanosomes of man or domestic stock was the big game of the 

 country. Removal of the population being impossible (and indeed 

 useless under the conditions) and there being no hope whatever, in 

 the present state of our knowledge,- of getting rid of the fly, while 



