420 
Tsetse Flies and Trypanosomiasis 
Despite numerous chances for error it is plain from the above table that 
following the climax of the epidemic there was a great reduction in the number 
of deaths per thousand of “possible victims” prior to 1909 when the survivors 
were removed from contact with tsetse. A decline is indicated by each year’s 
death returns except for the year 1907, when an increase is recorded among the 
Buvuma islanders and no decrease indicated among the Basesse. This is 
explained by the fact that the mainland shore was depopulated during this 
year, and that the natives possessing canoes and dependent on fishing moved 
(with their sick) to the islands, instead of moving inland, away from the lake 
shore. This caused a sharp increase in the number of deaths recorded from the 
islands, which is complemented by a corresponding decrease in the number 
of deaths recorded from the mainland. If allowance were made for this, it 
would indicate an even greater decline in deaths per thousand among the 
“possible victims” than indicated by the table, the errors in which are mostly 
on the conservative side. 
The steady decline in the virulence of the epidemic as indicated by the 
declining number of deaths in Buganda Province was only in part due to 
reduction in number of “possible victims”; for all the islanders were regarded 
as in this category and the number of deaths per thousand among them was 
declining only a degree less rapidly than the total number of deaths. If this 
had been as evident prior to 1909 as it subsequently became, it is doubtful if 
such drastic measures would have been adopted for “preventing spread” of 
infection. 
There is no doubt that there prevailed in the minds of those engaged in 
investigating the epidemic, between 1902 and 1906, an impression that a 
relatively enormous percentage of the population of the fly zone was already 
infected, and therefore doomed. 
Thus Gray, speaking of the Buvuma in a report on the work done at the 
sleeping sickness camps up to the end of November, 1907, states “I am in¬ 
clined to a belief that, if a systematic examination was made of the inhabitants 
of these islands, the percentage of infected persons would be found to be 
95 per cent, if not more (6). Of the Basesse, Koch in 1906 expressed the opinion 
that nine-tenths of the natives who were living in the archipelago seemed to 
be already infected and that, failing the discovery of a therapeutic cure, all 
would die” (7). 
When the question of segregation camps was first considered, Koch was 
of the opinion that nine camps would not be sufficient to accommodate all the 
sick. Events proved that four were amply sufficient. 
These impressions were undoubtedly based on the presumption, proved 
correct in many instances, that all cases of trypanosome fever developed into 
sleeping sickness. This assumption was strongly sustained by report and by 
the belief that the disease was literally exterminative locally, as on some of 
the Sesse and Buvuma Islands, leaving no survivors. It is a point of great 
importance, however, that no large number of individual cases was detected 
