Pathological studies on experimental Trypanosoma evansi infection in Swiss albino mice

The pathology of Trypanosoma evansi infection was studied in Swiss albino mice using cattle isolate of the parasite. Sixteen Swiss albino mice were used in the experiment and were divided into two groups viz. infected group (I) and uninfected healthy control group (II) comprising 12 and four mice, respectively. Twelve mice from group I were infected with 1 × 10(5) purified trypanosomes. Systematic necropsy examination specifically of the infected mice (group I) as well as of healthy control (group II) was performed and pathological changes were recorded. The different tissue samples were collected in 10 % neutral buffered formal saline and were used to study the histopathological changes. Gross post-mortem examination revealed enlargement of spleen, petechial haemorrhages in liver in the terminal stages of disease. Tissue sections revealed presence of numerous trypanosomes in blood vessels of liver, spleen, brain and kidneys. Microscopically, liver revealed lesions varying from vacuolar degeneration, coagulative necrosis along with congestion and haemorrhages. Spleen showed extensive haemorrhages in red pulp area, haemosiderosis and aggregation of histiocytes resulting in multinuclear giant cell formation. Lungs revealed oedema, congestion and mild inflammatory changes. Brain revealed mild degenerative changes along with congestion of meningeal blood vessels. Kidneys showed tubular degeneration, congestion and cellular infiltration. Heart revealed mild degenerative changes along with interstitial oedema. All changes were consistent with trypanosome infection and were confirmed by presence of trypanosomes in most of the tissue sections examined.