Abstract:
Haematological aberrations associated with human infective trypanosomes were investigated in the vervet monkey model of
the Rhodesian sleeping sickness. Four monkeys were infected intravenously with 104 Trypanosoma brucei rhodesiense and
monitored for changes in the blood profile using a haematological analyser. A chronic infection lasting between 48 and 112
days was observed. Microcytic hypochromic anaemia, which was characterized by a decline in packed cell volume (PCV),
red blood cell (RBC) numbers, mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCH)
developed at an early stage, and persisted throughout the infection. The mean platelet counts declined significantly from 3 x
105/μl (day 0 post infection) to 6.8 x 104/μl (day 7 post infection) and remained low in all the animals. However, the mean
platelets volume rose during the course of the infection. An initial decline in total white blood cell (WBC) counts occurred
between day 0 and 7 (3.1 x 106/μl) and remained low up to day 35 post infection (3.5 x 106/μl). This was followed by an
increase in WBC counts, principally associated with increased lymphocyte numbers. It is concluded that microcytic
hypochromic anaemia, thrombocytopaenia and an initial leucocytopaenia are the most important haematological changes
associated with a chronic infection of T.b. rhodesiense infection in vervet monkeys
