The histopathological effects of Trypanosoma evansi on experimentally infected mice

Abstract

Objectives The objective of this study was to study the histopathological changes in different tissues in experimentally Trypanosoma evansi-infected mice. Background There is variation in the pathogenicity of different host species. Animals that are subjected to stress, malnutrition, pregnancy, or work are more susceptible to this disease. The pathogenesis of T. evansi is complex and the cause of death is still somewhat obscure. Materials and methods The T. evansi isolate used in the present study was obtained from the blood of naturally infected camels. The strain was maintained in mice, where their infected blood was used for inducing the experimental infection. Giemsa-stained blood films were prepared for detection of infection and estimation of parasitemia. A total of 64 mice were divided into two main groups as follows: group I (the infected group), which included 40 mice inoculated with T. evansi strain, and group II (the control group), which included 24 mice used as uninfected healthy controls. Results In the present study, trypanosomes were observed using wet blood films and Giemsa-stained blood films at 48 h after infection in infected mice (group I) and there was high parasitemia on approximately the fifth day after infection (subgroup I-b). Mice from the uninfected control group (II) remained negative for trypanosomes until their death. Gross examination of various tissues from the infected mouse subgroups (infected group I) revealed splenomegaly, hepatomegaly, and marked congestion of lungs. All degrees of inflammation were detected in these tissues. Moreover, most of the examined tissues showed trypanosomes. It was noted that these pathological changes were more obvious in subgroup I-b when the parasitemia had reached its peak. Conclusion Microscopic examination showed significant histopathological changes in different organs, and in most examined tissues the parasites were detected in high numbers, especially in subgroup I-b (on the fifth day).