28o 



NA TURE 



[May 5, 1910 



With regard to the treatment of sleeping sickness, 

 Prof. Beck deals with the use and effects of atoxyl, 

 and Prof. Kleine with those of other drugs, of which 

 a variety were tried, but with results inferior to those 

 yielded by atoxyl. For combating sleeping sickness 

 Dr. Koch lays stress on the importance of discover- 

 ing the infected persons in the earliest stages of the 

 disease, both because curative treatment has then 

 most chance of success, and also in order to prevent 

 them from spreading the infection. The treatment 

 should be carried out in concentration camps situated 

 in places free from tsetse-flies. Healthy populations 

 should be hindered from access to the lake-shore 

 except at places cleared of the vegetation which 

 shelters the tsetses, and the collection of rubber 

 should be forbidden so long as there is danger of 

 infection in the forests on the shore. The tsetse-flies 

 should be kept in check by clearing vegetation in 

 their haunts and by destroying the crocodiles, their 

 principal food supply ; this object is to be effected by 

 encouraging the destruction of the nests and eggs of 

 these reptiles. In view of the voracity of tsetse-flies 

 and the readiness with which they suck the blood of 

 any vertebrate animal, it may well be doubted 

 whether the extirpation of crocodiles, though very 

 desirable for many reasons, if practicable, would fiave 

 the desired effect of diminishing the numbers of the 

 flies to any appreciable extent. 



(2) The bibliography of trypanosomiasis issued by 

 the Sleeping Sickness Bureau is a labour-saving pub- 

 lication that will be most useful to those occupied 

 with any problems, whether medical or scientific, 

 relating to trypanosomes and their hosts, vertebrate 

 or invertebrate. It aims at being complete up to 

 March 31, 1909, and contains references, alphabetic- 

 ally arranged, to about 1900 original memoirs, 

 articles, and treatises, catalogued under the authors' 

 names, and numbered in order. In addition to these 

 numbered references, the titles of journals that con- 

 tain literature on trypanosomes or tsetse-flies are in- 

 serted without numbers, followed by a list of the 

 articles or memoirs they contain, so that it is pos- 

 sible to look up the title of a journal in the catalogue 

 and find what papers on trypanosomes or tsetses have 

 been published in it. It is stated that a subject-index 

 is in course of preparation, to be issued as a supple- 

 mentary pamphlet, indicating the numbers in the 

 bibliography to be consulted for the various subjects. 



(3) The thirteenth Bulletin of the Sleeping Sickness 

 Bureau begins a second volume of this most useful 

 publication. Amongst other subjects, the present 

 number deals with the transmission of trypanosomes, 

 the treatment of trypanosome-infections, methods of 

 destroying tsetse-flies, and the alleged occurrence of 

 " ultra-microscopical " forms of trypanosomes. An 

 interesting account is given of a method of destroy- 

 ing tsetse-flies, discovered by Mr. Maldonado, 

 manager of an estate on the island of Principe, who 

 observed that these flies attacked the backs of 

 labourers stooping at their work in the fields ; he 

 caused the labourers to wear on their backs black 

 cloths coated on the outer surface with a glutinous 

 substance. In this way 133,778 tsetse-flies were 

 trapped on one plantation during some twenty 

 months. This method may be found useful, it is 

 suggested, for keeping down Glossina palpalis in 

 places where clearing is impracticable. A very use- 

 ful feature of the Bulletin is a section entitled " Sleep- 

 ing Sickness News," in which information is given 

 concerning recen* developments of the disease and 

 measures taken to check it. 



(4) Sir Hesketh Bell gives a historical account of 

 the progress of discovery and research, and a sum- 

 mary of the results gained, with regard to sleeping 



NO. 2 1 14, VOL. 83] 



sickness. He then describes the administrative 

 measures taken in Uganda to combat the disease. 

 These measures may be summarised as follows :— 

 (i) The removal of infected persons into fly-free areas, 

 that is to say, more than two miles away from the 

 lake-shore, in order that they shall not render the 

 tsetse-flies infective and capable of transmitting the 

 disease to healthy persons ; for this purpose segrega- 

 tion camps have been started in which those afflicted 

 with the djsease are put under medical treatment ; 

 {2) the removal of healthy persons from areas infested 

 by tsetse-flies, until such time as the flies may be 

 supposed to have lost their infectivity ; (3) the extirpa- 

 tion or banishment of the fly, by clearing the forest 

 on the foreshore of Lake Victoria, in those places, 

 such as ferries or ports of main trade-routes, from 

 which it is not practicable to remove the population. 

 The task of keeping the foreshore clear is stated to 

 have been aided greatly by planting the cleared area* 

 with citronella-grass, which grbws^ rapidly, and is also 

 of commercial value, yielding a considerable amount 

 of valuable oil. 



These measures, when first planned, were based 

 on the belief that the tsetse-fly only transmitted the 

 disease mechanically and did not remain infective for 

 a longer period than forty-eight hours, a belief 

 founded on the experimental results of scientific in- 

 vestigations which had at that time demonstrated 

 clearly the existence of so-called "direct" or 

 "mechanical" infection, but had failed to obtain 

 evidence for the occurrence of deferred or "cyclical" 

 transmission. Consequently it was thought that the 

 flies would lose their infectivity very quickly when 

 they could no longer suck the blood of diseased 

 persons. The recent researches of Kleine and Bruce, 

 however, have shown that the trypanosome of sleep- 

 ing sickness goes through a developmental cycle in 

 the tsetse-fly, and that when once the trypanosome 

 has established itself, the fly remains infective, 

 apparently for the rest of its life, without again feed- 

 ing on the blood of an infected person. It follows 

 from this discovery that the period for which healthv 

 persons must be removed from the fly-belts, in order 

 to ensure that the infection has died out in the flies, 

 is much longer than was thought, and cannot at 

 present be stated definitely. There are two further 

 possibilities to be borne in mind, neither of which 

 have as yet been proved, though often suspected, to 

 exist, and which greatly complicate the problem of 

 the transmission and spread of the disease. One is 

 that an infected tsetse-fly maj' transmit the infection 

 to its ofl'spring ; the other, that some vertebrate 

 animal other than man may harbour the trypanosome 

 of sleeping sickness in its blood, and so be a "reser- 

 voir-host " which keeps up the infection in the flies. 

 It must also be remembered that to keep the natives, 

 probably much against their inclinations in many 

 cases, more than two miles from the shore along the 

 immense coast-line of the Victoria Nyanza must be 

 a task of considerable difliculty and of uncertain 

 result. The natives concerned are evicted from the 

 homes which they and their ancestors have inhabited 

 for untold generations, and, moreover, they are for 

 the most part extremely sceptical as to the agency 

 of the tsetse-fly in the transmission of the disease. 

 It is therefore extremely probable that in spite of 

 administrative prohibitions, leakage, so to speak, 

 sometimes occurs, and natives evade the regulations 

 against frequenting the danger zone. In a recent 

 communication to the Royal Society (vide Proceed- 

 ings, 1909) Bruce and his collaborators state that they 

 have found tsetse-flies still infective that were caught 

 in localities from which the natives had been removed, 

 and conclude that the tsetse-flies "can retain their 



