47 



about 2 days march north of the Liwale-Kilwa road and about 

 150 miles away from the foci on the Rovuma), in the Lukuledi Valley 

 (about 3 days march westwards of Lindi), and on the Lurio River 

 near Kwa Nluku in Portuguese Nyasaland. Furthermore the district 

 between Nangware and Mtarika-Chirumba on the Lujenda River that 

 had been suspected of being infected was definitely proved to be so. 

 (According to verbal information from Enghsh Medical officers another 

 focus of T. rhodesiense exists about 18 miles inland from Port Ameha.) 

 In all these foci human trypanosomiasis was of old standing, as proved 

 by the occurrence of cases immediately after occupation by the troops, 

 but the disease had not been noticed before. This shows the great 

 value of systematic travel by medical specialists and its superiority 

 to professional work in the stations, for the damage resulting from 

 a tardy discovery of an epidemic or endemic is seldom reparable. 



As the distribution of Glossina morsitans practically coincides with 

 that of T. brucei it follows that the comparatively small foci of 

 T. rhodesiense are included in the large areas of distribution 

 of T. brucei, but the epidemiological observations referred to — ■ 

 which agree with the authors' previous assumptions-show that the 

 distribution of T. rhodesiense must be distinguished from that of 

 T. brucei. At the Kiulimila water-hole and on the Lukuledi River 

 the former trypanosome is restricted to the road along which the 

 infected plantation labourerb from the Rovuma River travel, Avhereas 

 T. brucei is spread over a territory of several hundred square miles. 

 It is remarkable that the newly discovered foci occur near rivers 

 or lakes just as is the case in the Luangwa Valley (North-eastern 

 Rhodesia), in British Nyasaland and on the Rovuma River. This 

 invites comparison with the distribution of T. gambiense, but the 

 authors think it probable that in the case of T. rhodesiense the 

 preference for water is due to the circumstances connected with the 

 movements of man and not to the biology of Glossina morsitans. 

 During the dry season the tsetse-fly regions are usually very parched 

 and lines of communication run near important streams. It is 

 especially at fords that conditions are favourable to the establish- 

 ment of foci. It is also possible that, as observed by Lloyd, the 

 pupation of G. morsitans is very abundant at fords or other chief 

 points of traffic, so that the flies congregate there. 



A remarkable series of experiments were made to test the identity 

 or non-identity of T. rhodesiense with T. brucei. In the first experi- 

 ment Dr. Taute and 10 native criminals were the subjects, and 

 injections of T. brucei proved negative. The same result attended 

 a further five experiments in different localities, the subjects including 

 both of the authors of this paper and 129 native carriers. The latter 

 belonged to 11 different tribes ; some came from districts where 

 T. rhodesiense is endemic and both sickly and healthy individuals 

 were included. The animals used, four horses and two mules, were 

 naturally infected. No laboratory strains were employed. These six 

 experiments agree with Taute\s pre-war ones and are held to confirm 

 the correctness of the view held by Kleine and others that T. rhode- 

 siense and T. brucei are not identical. 



Little or no success has hitherto attended measures directed against 

 the widespread nagana of animals and only two alternatives are 



