Pathological changes in rats and rabbits experimentally infected with Trypanosoma evansi

Macroscopical and microscopical lesions in visceral organs of experimental Trypanosoma evansi infected rats and New Zealand White rabbits were studied at the height of parasitaemia. Excessive accumulation of fluids in the abdominal and thoracic cavities, mottling with necrotic edges in liver, splenomegaly and congestion of meninges of brain were prominent gross lesions. Microscopically, fatty degeneration in liver, serous exudations under pleura, emphysema with infiltration of polymorphs, lymphocytes and mononuclear cells in lungs were found. The changes in the spleen include massive hyperplasia of lymphoid tissue at Malpighian corpuscles along with haemosiderin pigments. Kidneys showed hyaline degeneration and epithelial casts in the proximal and distal tubules. Congestion of meninges with focal submeningeal oedema with encephalomalacia was noticed in brain. It is proposed that the pathological changes of these organs might be due to immune complex deposition and complement cascade reaction.