Studies of diminazene efficacy with ascorbate supplementation in experimental murine Trypanosoma congolense infection

Abstract

The efficacy of diminazene aceturate with and without ascorbate supplementation in rats experimentally infected with Trypanosoma congolese was investigated. Changes in parasitemia, blood parameters (Haematocrit (PCV), haemoglobin concentration and erythrocyte counts), liver, spleen and heart masses and histology were evaluated 7 days after T. congolense inoculation (untreated rats) and 7 and 14 days after diminazene aceturate (7 mg/kg) intramuscular injection with and without daily ascorbate (200, 400 or 800 mg/ kg) supplementation via oral cannula. Parasitemia was evident by day 5 post infection and all untreated rats died within 14 days post inoculation. No significant morphological and histopathological changes were found in the heart and liver. The spleen was significantly enlarged but no histological lesion was evident. Diminazene treatment efficiently reduced the increase in spleen weights on day 7. Treatment was effective on day 14 only in the ascorbate supplemented groups. Erythrocyte parameters were also significantly reduced in infected rats. Neither treatment with diminazene alone nor diminazene/ascorbate combination significantly reversed the fall in PCV, Hb and RBC values. Parasites were absent in the blood by day 7 post treatment (PT) in both diminazene and diminazene/ascorbate groups but parasite resurgence was observed on day 14 without ascorbate supplementation. These results showed that the efficiency of treatment with diminazene aceturate alone or combination with ascorbate was limited in T. congolense infection, apparently because of early re-emergence of the parasite which may be related to its virulence or to its resistance to diminazene.

Keywords: Ascorbate, Diminazene, Haematology, Liver, Murine, Parasitaemia, Spleen, Trypanosoma congolense