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T ryjKinosom iasis 
Sleeping Sickness. 
Trypanosoma gambiense, the cause of sleeping sickness in Uganda 
and the West Coast of Africa, is conveyed by Glossina palpalis. It has 
been estimated that 0‘03 to 0'34< "/o of wild palpalis in the endemic area 
in Uganda are infective. Infective flies have been captured on the 
shores of Lake Victoria Nyanza which have been uninhabited by man 
for three years, and they have been found on islands from which the 
human population has been removed for ten months. There is no 
evidence that T. gambiense is hereditarily transmitted to the offspring 
of an infected fly, and it cannot be a.ssumed that palpalis in nature can 
live for any such period. We were, thei’efore, forced to conclude that 
animals inhabiting this region must be susceptible to infection and capable 
of harbouring the trypanosome. It is now definitely established that 
certain animals do serve as reservoirs whence the flies may derive the 
parasite in the absence of man. The latest reports prove that antelope 
(bush-buck, reed-buck and water-buck) may harbour the tiypanosome 
in nature. Antelope kept under observation have been seen to recover 
from any clinical manifestations of the disease and to appear perfectly 
healthy for 12 to 22 months, but they continue to harbour T, gambiense 
during this period and possibly longer, and throughout this long 
interval of time they may, as has been experimentally shown, infect 
clean palpalis w'hich have been raised in the laboratory. Although 
there is evidence that with time the antelope’s blood grows less virulent, 
as tested by inoculation into susceptible animals, and that antelope 
acquire a form of immunity, they harbour virulent gambiense for 
a sufficient length of time to maintain the parasite in nature in the 
absence of man. As in other diseases, so with trypanosomiasis, it is 
the chronic cases which serve as “ reservoirs ” for lengthy periods, and 
are most dangerous in relation to the spread and persistence of the 
disease in the region affected. The relation of game animals in 
respect to sleeping sickness in man is therefore similar to that of game 
in relation to Nagana in domesticated animals; in both cases game 
may serve as a reservoir whence the Glossinas draw their infection. 
The wide range of pathogenicity possessed by T. gambiense renders it 
certain that it must, in nature, find reservoirs in other animals than 
antelope. In fact, the trypanosome has been recovered from cattle, 
monkeys (Ger copith ecus, twice) and dogs under natural conditions. 
A large series of animals has been proved to be susceptible to infection 
by inoculation with T. gambiense of human origin. Without, perhaps. 
