Comparative haematological study of single and mixed infections of mongrel dogs with Trypanosoma congolense and Trypanosoma brucei brucei.

The haematological effects of single and mixed infections of Trypanosoma congolense and Trypanosoma brucei brucei were compared in experimentally infected mongrel dogs. Twenty mongrel dogs of both sexes aged between 3 and 6 months, and weighing between 2.5 and 5.9 kg were used for the study. The dogs were kept in clean metal cages in a fly-proof house and were adequately fed and given water ad libitum. The twenty dogs were divided into four groups of five dogs each. Group I dogs were uninfected control, group II dogs were infected with T. congolense, group III dogs were infected with T. brucei brucei and group IV dogs were infected with both T. congolense and T. brucei brucei. Parasitaemia occurred in the infected dogs in groups II, III, and IV; 10-13 days post-infection (PI) with the mean pre-patent period (PPP) of 12, 10, and 11 days respectively. Mixed infection persisted throughout the duration of the experiment. T. brucei predominated T. congolense in the mixed infection constituting about 70% of the trypanosomes. The significant (P<0.05) decrease in the mean haemoglobin concentration (Hb) and packed cell volume (PCV) caused by the infection did not differ significantly (P>0.05) between the infected groups. Also the significant (P<0.05) reduction in the total white blood cell count (TWBC) caused by the infection did not differ significantly (P>0.05) between the infected groups. The decline in the total WBC count was due primarily to significant (P<0.05) reduction in the lymphocyte counts of the infected dogs. It was thus concluded that single or mixed infection of mongrel dogs with T. congolense and T. brucei brucei resulted in anaemia and leucopenia which did not differ significantly (P>0.05) among the infected groups.