H. L. Duke 
357 
lake-shore trypanosomes, with the object of settling their relationship to man. 
Such investigations are necessarily prolonged and indirect. The decisive ex¬ 
periment of Taute is not possible under British rule. It has been deemed 
advisable to publish the indications that may emerge from experiments as 
they occur, and the present paper covers the period from late 1919 to April 
1921. It must be pointed out that this fly and trypanosome work, which at 
Mpumu received my undivided attention, has been carried out at Entebbe 
in conjunction with the routine work of the laboratory, and other investiga¬ 
tions ; and this circumstance is my excuse for some of its evident shortcomings. 
I wish to express my gratitude to Prof. Clifford Dobell, F.R.S. for valuable 
suggestions as to the arrangement of this paper, and to Capt. R. L. Sheppard, 
Librarian to the Tropical Diseases Bureau, who most kindly checked and 
completed the list of References. 
PART I. REFLECTIONS ON THE AETIOLOGY OF THE 
UGANDA EPIDEMIC. 
{a) Lack of definite evidence of the occurrence of human trypanosomiasis 
in Uganda lake-shore fly areas before the epidemic. 
The distribution and affinities of the polymorphic organism on the island 
and mainland shores of Lake Victoria before, during, and after the epidemic 
are of extraordinary interest. A perusal of Koch’s reports of his inspection 
of the Mwanza and Shirati districts in 1906-7, reveals the existence in 1907 
of what is described as an endemic focus of trypanosomiasis, among natives 
who had never left the district, in the isolated village of Mohurru, to the 
north of Shirati (Koch, 1906). It is not quite clear whether the word endemic 
in this connection can be taken to mean a pre-existing focus of long standing 
and quite independent of the well-known extension from east to west round 
the shores of the lake. 
Again, in a report from the Medical Officer of Health at Kisumu, Dr 
de Boer, dated 13 December, 1920, describing the occurrence of human 
trypanosomiasis at Nyakatch near Kisumu, it is stated that the disease had 
been present in Nyakatch for some 15 years and had spread from Kadimu, 
where it had existed for a very long time. The cases brought to Kisumu were 
in an advanced stage of the disease. 
Such references suggest that human trypanosomiasis, existed in pre¬ 
epidemic days along the shores of Lake Victoria. Sir Apolo Kagwa, the 
Prime Minister of LTganda, has very kindly made exhaustive enquiries for 
me in the Native Parliament and elsewhere regarding the diseases occurring 
in Sesse and Buganda before the onset of the epidemic. One result of these 
enquiries is that I must correct the statement made in 1919 (Duke, 1919 b) 
that the existence of the word “mongota 5 ' in the Buganda language is of 
itself evidence that an identical or similar disease existed previous to the 
recognition of sleeping sickness in 1901. The statement was that “there is 
