Comparative pathology of mice infected with high and low virulence of Indonesian Trypanosoma evansi isolates.

Mice infected with T. evansi cause various clinical manifestations and histopathological changes. The aim of this study was to compare the histopathological lesions of mice infected with T. evansi Bang 87 isolates (high virulence) and Pml 287 isolates (low virulence). A total of 15 susceptible mice (DDY) were divided into three groups (five mice/group): Groups I and II each were infected with 104 T. evansi of high virulence (Bang87) and low virulence (Pml 287), respectively, whereas group III served as a control group. A total of three mice from group I, and one mouse from each group II and III were killed at 4 dpi. A total of two mice from each group II and III were killed at 24 dpi. Two remaining mice from each group were observed until succumb. Mice of group I and group II at 4 dpi showed no gross lesions. However, mice of group I showed very acute animal death at 5 dpi and showed mild to moderate histopathological lesions at 4 dpi, namely non-suppurative encephalitis, non-suppurative pneumonia, hepatitis non-suppurative with intravascular trypanosomiasis, tubular degeneration and necrosis. Group II showed chronic death at 26 dpi with significant gross pathological changes at 24 dpi in spleen (swelling 10 times than normal size) accompanied by severe non-suppurative encephalitis, cholangiohepatitis non-suppurative and bile duct proliferation, diffused splenic necrosis. The result of this study is expected to be used as a basis for improved treatment management in cattle infected with high virulence T. evansi isolates that are need to be handled appropriately to avoid fatal consequences. © Indian Society for Parasitology 2021.