The Pathogencity and Drug Resistance of Trypanosoma Vivax in Calves and Goats

Abstract

A survey was conducted at the Blue Nile area to determine the prevalence of Trypanosoma vivax in cattle, using haematocrit centrifugation technique, wet blood film, thin and thick stained smears. The results showed that the prevalence rate during the dry season varied between 6.5 to 2.2% and 6.35 to 1.43% during rainy season, and the tabanids catches were 25±5.1 fly/trap/day in early dry season. This indicated that cattle suffer due to T. vivax is quite prevalence in the area, the rate is high with seasonality. The trypanocidal drug resistance studies of T. vivax stock isolated from non-tsetse area were conducted in 32 goats. Trypanocidal drug tested were Homidium bromide (16 goats). The doses tested for homidium bromide were the recommended treatment dose of 0.5 /kg body weight and double that dose. The doses tested for diminazine aceturate were the recommended treatment dose (7mg/kg). The T. vivax stocks tested against both drugs relapsed indicating the development of drug resistance against both drugs at the tested doses. Both groups of goat treated showed significant reduction in PCV Hb. WBC and RBCs count. The pathological effect of T. vivax stocks isolated from non tsetse area was conducted by experimental infection of 10 Kenana calves. The infected animals showed obvious, emaciation anaemia, enlargement of lymph node, high, temperature, increase in heart and respiratory rates, which were positively correlate with peak of parasiteaemia. The blood showed significant haematological changes. The PCV values dropped to 15%, Hb 8%, WBCs 5001.696 ±162.725, RBCs 3554018 ±172889.0. The gross findings showed petechial and echmotic haemorrhages in all the visceral organs spleen, liver, heart and lymph nodes wereconsiderably enlarged, oedema and pulmonary exudate were observed in the lungs, the heart showed myocardial degeneration. Also proliferative lymphoid changes and infiltration of lyphatic cells were observed in all tissues. The kidneys showed interstitial glomerulonephritis, and inflammatory changes and the testis showed prominent orchitis, epididymitis, atrophic seminepherous tubules and degenerative changes. The brain showed infiltration of lymphoid cells, histocytes, mononuclear and glial cells and necrotic foci. Generally wide tissue damage, and haematic changes were observed in all tissues of the infected animals died of and the congestive heart failure.