6 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
II. HUMAN TRYPANOSOMIASIS 
We have decided to retain the term Human Trypanosomiasis' 5 as a convenient 
heading under which to discuss all cases in which the human subject is infected with 
trypanosomes, quite irrespective of the clinical symptoms characterizing the case 
under consideration. At the same time we recognize that a more extended sub- 
sidiary nomenclature may become necessary to indicate special morbid types of 
infection produced by these flagellata. For example, the type of illness now several 
times observed in Europeans infected with them has been called ' trypanosome fever.' 
Distribution and Prevalence 
Our first endeavour on reaching the Gambia was, naturally, to find a second 
case of trypanosomiasis. 
A native child was known to have been infected, and we, therefore, determined 
to examine the blood of as many persons as possible, both black and white. Since 
parasites very similar to those already seen in man were known to occur in mammals, 
and since it was not impossible that they might be infected with the human trypano- 
some, it was necessary to include them in our examinations, all of which were made 
in the same way. 
Our routine method for the detection of parasites in the peripheral circulation 
was, we are aware, imperfect. The exigencies of travelling, together with the length 
of time necessary to make preparations, prevented the constant employment of the 
centrifuge and animal inoculations as diagnostic methods. A coverslip preparation, 
for immediate examination, and a film for staining subsequently, were taken from 
each individual examined. Names were also recorded, and, in the event of infection, 
the case was recalled for further examination. 
Distribution 
The accompanying map of the Gambia, though not minutely exact, will give 
a very excellent idea of the localities in which we worked, and will, with the following 
table, indicate very precisely the numbers of natives examined in each district. 
Those towns in which infected individuals were found are in italics. 
