Clinical and Haematological Studies in Dogs with Single and Mixed Experimental Trypanosoma Brucei and Ancyclostoma Caninum Infection

Abstract

Trypanosomosis is one of the most devastating diseases of animals caused by infection with a protozoan parasite trypanosome, which is transmitted by tse-tse fly. Besides anaemia, which is a cardinal symptom of the disease, infection also impairs the immune system of animals and renders them more susceptible to other. Under natural field condition, in areas where trypanosome and helminth parasites are endemic, mixed infection appears to be common. A study was conducted to determine the clinico-haematological manifestations in dogs experimentally infected with Trypanosoma brucei and Ancylostoma caninum singly and in combination. Twenty young local dogs were used in the study. They were randomly grouped into 4 with 5 dogs in each group; group A (uninfected control), group B (infected with A. caninum), group C (infected with T. brucei) and group D (mixed infection with A. caninum/T. brucei). For the mixed infection, dogs were initially infected with A. caninum and then T. brucei infection superimposed 23 days later by the time of patency of Ancylostoma eggs in the stool. Results of this study showed that the prepatent period (PP) of A. caninum infection in the dogs was 24.5±0.4 days. The PP of T. brucei infection alone was 5.0±0.0 days, but was 4.6±0.22 days in the mixed infection. Clinical signs of dullness, inappetence, anorexia, weakness, pale mucous membrane due to anaemia, rough hair coat were encountered in both infections. Additionally, specific signs of bloody diarrhea and sunken eyes were present in A. caninum infected dogs while fever, swollen face, bilateral ocular discharge and corneal opacity accompanied T. brucei infection. A combination of these signs in a more severe form characterized the mixed infection of both parasites. There was a significant decrease (P<0.05) in the packed cell volume (PCV) in all the infected groups (B, C and D) as from day 19 post infection (p.i.). Infection with Ancylostoma caninum caused significant increase (P<0.05) in the total leucocyte count of the dogs in group B from day 29 p.i., whereas significant decrease were recorded in trypanosome infected dogs group C and in mixed infection group (D) on days 38 and 34 p.i., respectively. The absolute neutrophil counts significantly increased (P<0.05) in group B by day 29 p.i. whereas significant decreases were recorded in groups C and D from day 34 p.i.. There was no variation in the absolute lymphocyte count except on day 20 p.i. when an increase was detected only in the mixed infection group (D). The absolute eosinophil counts significantly increased (P<0.05) in group B from day 14 p.i. in contrast to a significant decrease (P<0.05) in the mixed infection group (D) by day 34 p.i. There was no significant variation (P<0.05) in the absolute monocyte counts of the infected dogs. The results of the egg per gram (EPG) of faeces on days 28, 34 and 39 were 20300±12195, 81233±26410 and 67683±13971 for group B, and 34325±8044, 54425±24764 and 55800±12304 for group D, respectively, and showed no significant difference (P>0.05). It was concluded that concurrent infection of T. brucei and A. caninum resulted in enhanced pathogenicity manifested in remarkable clinico-haematological alterations in the infected dogs.