85 
villages along the Luapula, although Gl. falfaLis is present and the 
people constantly exposed to their bites. The infection can be 
clearly traced, then, from Kabinda to Lake Kisale, from there south¬ 
wards to some of the Katanga mines,* and from these again it has 
been brought into Rhodesia. 
As regards the Northern portions of the country around Mweru 
and Tanganyika, we have at present no personal experience, but 
there is reason to believe that cases also exist there. These would 
not necessarily be introduced from the Katanga although the possi¬ 
bility of this must not be overlooked. Very large numbers of natives 
from these districts have worked in the mines, and since cases have 
occurred amongst those who went from the Luapula division, there is 
just as much reason to expect that cases will be found in all the 
districts from which labour has been drawn. The other point of 
introduction would be from the endemic centres along the higher 
reaches of the Luapula, and from Lake Tanganyika. In 1901, 
imported cases were present at Moliro,® in 1902, at Baudoinville, and 
within the last year the disease has been reported as being endemic 
in the vicinity of Vua. As fly exists {Gl. palpalis) along the shores 
of Mweru and Tanganyika, as the people have been communicating 
freely, and as there have been numbers of Swahili traders crossing 
from one country to the other with their retinues, cases of the 
disease might reasonably be looked for. There is good reason to 
believe that these are present. 
All these points bear out in a striking manner the correctness of 
Dutton and Todd’s^ observations on the way in which the disease has 
been carried from an infected to a non-infected region. 
TRANSMISSION OF THE DISEASE 
Wherever sleeping sickness has been found, its distribution has 
been closely related to that of Glossina palpalis. This has been 
accepted as showing more or less conclusively that the disease can 
only be transmitted by this species. While it would be idle to ignore 
the inferences implied by this relationship of the disease and Gl. 
palpalis, there is little foundation for the belief that this fly only is 
. *, 4* P*|sent there are a number oI cases of human trypanosomiasis in the 
Hospital at Ruwe, and until very recently, at all events, at Kambove as well. 
G 
