TRYPANOSOMIASIS EXPEDITION TO THE CONGO 
37 
OBSERVATIONS ON THE PARASITE 
Periodicity and Frequency of Occurrence in the Peripheral Blood 
Frequent examinations ot the finger blood of trypanosome cases have shown that 
the parasites may, to the ordinary methods of examination, be absent from the 
peripheral blood for varying periods. This periodicity is illustrated by the two 
following cases : — 
Case 101. Oporanga. Regular observations were made about every third day, 
commencing on January 3, 1904, when no parasites were seen. The periods of 
presence or absence of the parasite from that date until death were as follows : — 
days 
absent 
11 
observations. 
3 
33 
present 
3 
7 
31 
absent 
4 
33 
3 
present 
3 
33 
absent 
14 
4 
■>■> 
present 
4 
3' 
6 
33 
absent 
3 
33 
This case shows comparatively long periods of absence. 
Unless especially stated the routine method of examination employed for the detection of the 
trypanosomes was the examination of a freshly made three-quarter inch square, cover-slip preparation of 
finger blood ringed with vaseline. 
Case 90. Bongwendie. Routine examinations commenced on January 19, 
when trypanosomes were found to be present. They had not been seen for tour 
days previously. 
3 
days present 
3 
observations. 
9 
absent 
4 
>J 
6 
33 
present 
4 
6 
absent 
4 
3' 
1 
33 
present 
1 
31 
2 
absent 
1 
1 
present 
1 
33 
5 
33 
absent 
4 
33 
33 
present 
1 
31 
3 
)> 
absent 
6 
33 
present 
5 
10 
'3 
absent 
7 
This case shows shorter periods of absence. 
