Comparison of the pathogenicity of Quinapyramine Sulphate drug-resistant and drug-susceptible Trypanosoma evansi in experimentally infected mice

Abstract

The pathogenecity of two stabilates of Trypanosoma evansi isolated from camels in El-Gedarif and North Kordofan States, to study and evaluate the biochemical and microscopical pathology of camel strains of T. evansi in vivo in experimentally infected Albino mice. Total of 36 adult male outbred Albino mice, weighing between 133-137g were used in this study. The mice were divided into 6 groups of 6 mice per group (A, B, C, D, E and F). Group A and B were infected, intraperitoneally, with T. evansi, drug-resistant, while group C and D were infected with T. evansi, drug-susceptible, with 1×104 trypanosome for the inoculum. Group B and D were given quinapyramine sulphate (20 mg/Kg bwt) after parasitaemia was evident. Group E and F were left as healthy uninfected controls for the two stabilates. (When parasite counts were one or more parasites per field, counting in haemocytometer was used for exact number of parasite per cubic millimeter using the method of Paris et al. 1982). Parasites from tail blood were first fixed, stained and diluted in trypanosome diluting reagent. The parasites were diluted to the level that can easily be counted in WBC counting chamber in the haemocytometer and the total number was expressed as log10 number of parasites per ml of blood. The presence and degree of parasitaemia were determined daily for each rat by examining tail blood. There was significant reduction in serum glucose, potassium and phosphorus as well as significant increase in Glutamate Oxaloacetate Transaminase (GOT), Glutamate Pyruvate Transaminase (GPT), creatinine, albumin, calcium, total protein, urea, and cholesterol in groups A, B and C. The different tissue samples were collected in 10% neutral buffered formal saline and were used to study the histopathological changes. Microscopically, brain revealed acute congestion of meningeal capillaries, perivascular oedema, neuronecrosis (vaculation), gliosis and trypomastigotes in dilated capillaries. The lung revealed oedema, congestion, multifocal alveolar emphysema, hyperplasia of the peri-bronchiolar lymphoid tissues and haemorrhages. The spleen showed extensive haemorrhages, haemosiderosis and aggregation of histiocytes resulting in multinuclear giant cell formation. The kidneys showed acute congestion of the glomerular tuft. All tissues obtained showed exactly the same histopathological changes. No significant histopathological alterations were observed in the liver and heart. The most consistent histopathological changes were seen in the brain, lungs, spleen and kidneys. These changes were consistent with trypanosome infection and were confirmed by presence of trypanosomes in most of the tissue sections examined