The effects of lactose infusion on the pathological manifestations of Trypanosoma vivax infection in cattle

Abstract

Except for 4 control calves, 8 calves were experimentally infected using 11 x 106 T. vivax Trypanosomes, intravenously, as a source of neuraminidase. At the peak of parasitaemia, lactose was intravenously infused at the rate of 0.5g kg-1 body weight into 4 of the infected calves, to inhibit the binding of desialylated erythrocytes to kupffer cells (macrophages), and therefore, subsequent erythrophagocytosis. This resulted in amelioration of the anaemia in the 4 infected, lactose infused calves which showed no gross lesions except for mild anaemia and emaciation. In contrast, the other 4 infected, non-lactose infused calves had marked anaemia. The mean PCV values were higher in the infected infused calves and the mean PCV values were lower in the infected uninfused calves, with a statistically significant difference (P<0.05). The 4 infected, lactose infused calves showed no gross lesions except for mild anaemia and emaciation. The major gross lesions observed in the infected non-lactose infused calves included rough hair coat, emaciated carcases, serous atrophy of coronary fat, enlarged oedematous lymph nodes, and hepato-splenomegaly. Two calves each from the infected lactose infused and non-lactose infused groups and one of the control calves were sacrificed for pathological examinations. Histopathological lesions in the infected-lactose-infused calves were narrow hepatic sinusoidal spaces, enlarged Bowman's spaces, hypercellular renal glomeruli, and a less dense lymphoid hyperplasia (proliferation of lymphocytes) in the spleen and lymph nodes compared to the infected-non-lactose infused calves. No significant histopathological changes occurred in the heart, lung, and intestine of the infected-lactose infused calves. In the infected-non-lactose-infused calves there were diffuse hepatic necrosis and erythrophagia by Kupffer cells, dense lymphoid hyperplasia (active lymphoid follicles with plasma cells), and haemosiderosis. There were haemosiderin laden macrophages in the spleen, liver, kidney, and lymph node. Hypercellular glomeruli, necrosis of the proximal, distal and collecting tubules of the kidney with periglomerular and inter-tubular mononuclear cellular infiltration. There was minimal myocarditis, while the brain, lung and the intestine of the calves had no significant histopathological lesions. No significant microscopic lesions were observed in the liver, kidney, lung, heart, spleen, lymph node, brain, and the intestine of the control calf examined. The results of this study have shown that lactose plays a vital role in the prevention or amelioration of tissue injury and cellular reactions in various organs of the body during the course of bovine trypanosomiasis. The finding further supports the safety use of lactose without causing any damage to body organs. As such, its incoporation with other chemotherapeutic agents for treatment of trypanosomiasis is, therefore strongly recommended.

Keywords: Trypanosoma vivax, cattle, lactose infusion, lectin, erythrophagocytosis, anaemia

Nigerian Veterinary Journal Vol. 26(1) 2005: 25-33