Hematological derangement patterns in Nigerian dogs infected with Trypanosoma brucei: A simple prototype for assessing tolerance to trypanosome infections in animals

Abstract

The haematology of Nigerian local puppies experimentally infected with the Federe strain of Trypanosoma brucei was studied in a total of six 9-weeks old puppies born to two local bitches. Four were randomly selected and inoculated with about 0.8 x 10⁶ of T .brucei subcutaneously and the remaining two served as the uninfected control. The parasitaemia was monitored daily using wet mount microscopy. The packed cell volume (PCV), red blood cell (RBC) counts, total and differential white blood cell (WBC) counts and rates of both red blood cell and white blood cell loss per day and per parasitaemia log equivalent value(LEV) were monitored twice in a week . Parasitaemia was detected in the infected group four days after infection which was followed by an acute disease course, though with low fatality rate in the dogs. The anemia was characterized by a fluctuating PCV decrease from the pre-infection value of 29.5±4.5% and 15.3±3.3% at two weeks after infection when one of the dogs died. There was a mild decrease in the overall erythrocyte values which was attributable to trypanotolerance in the local breed of dogs. The post infection hematological derangement pattern was characterized by an overall post-infection RBC count drop of 1.92+0.23(x 10¹²/μ) (39.0%), mean daily drop of 0.07+0.05 (x 10¹²/μ) and an overall drop per LEV of 0.69(x 10¹²/μ). The overall mean postinfection total WBC count drop was 0.61±0.15(x109/μ)(43.6%) with a mean daily drop of 0.02±0.14(x10⁹/μ), and an overall drop per LEV of 0.22±0.44(x10⁹/μ). There was an overall higher post infection leukocyte drop compared to erythrocyte. The result poses fundamental research questions on the likelihood of differential surface sialic acid contents of erythrocytes and leukocytes and the possible roles of trypanosome sialidase in creating this difference as well as enhancing pathogenesis of leucopenia in the dogs . It was concluded that the patterns of hematological derangements demonstrated as erythrocyte and leukocyte drop (loss) rates and drop per parasitaemia Log Equivalent Values could serve as a prototype for comparing susceptibility to animal and human T. brucei infections and, other trypanosome species.

Keywords: Federe, Trypanosoma brucei, haematology, derangement, patterns