In vivo experimental drug resistance study in Trypanosoma vivax isolates from tsetse infested and non-tsetse infested areas of Northwest Ethiopia

Dagnachew, S., Terefe, G., Abebe, G., Barry, D., McCulloch, R. and Goddeeris, B. (2015) In vivo experimental drug resistance study in Trypanosoma vivax isolates from tsetse infested and non-tsetse infested areas of Northwest Ethiopia. Acta Tropica, 146, pp. 95-100. (doi:10.1016/j.actatropica.2015.03.014) (PMID:25792418)

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Abstract

Ethiopia, particularly in the Northwest region, is affected by both tsetse fly and non-tsetse fly transmitted trypanosomosis with a significant impact on livestock productivity. The control of trypanosomosis in Ethiopia relies on either curative or prophylactic treatment of animals with diminazene aceturate (DA) or isometamidium chloride (ISM), respectively. However, since these two trypanocides have been on the market for more than 40 years, this may have resulted in drug-resistance. Therefore, in vivo drug resistance tests on two Ethiopian isolates of Trypanosoma vivax were completed, one from an area where tsetse flies are present and one from an area where tsetse flies are not present. Twenty four cattle (Bos indicus) aged between 6 and 12 months, purchased from a trypanosome-free area (Debre Brehan: Northcentral Ethiopia) and confirmed to be trypanosome-negative, were randomly assigned into four groups of six animals, which were infected with T. vivax isolated from a tsetse-infested or non-tsetse infested area, and in each case treated with curative doses of DA or ISM. Each animal were inoculated intravenously 3 × 106 trypanosomes from donor animals. Parasitaemia became patent earlier in infections with non-tsetse T. vivax (∼7 days post-infection) than tsetse (∼14 days post-infection). Both groups were treated at the highest peak parasitaemia with DA or ISM and nine cattle, four with non-tsetse T. vivax (two ISM- and two DA-treated) and five with tsetse T. vivax (three ISM- and two DA-treated) showed relapses of parasitaemia. Moreover, treatment did not improve diagnostic host markers of trypanosome infections in these animals. In conclusion, in vivo drug tests indicated the presence of resistant parasites (>20% of treated animals in each group relapsed) against recommended doses of both available trypanocidal drugs.

Item Type:Articles
Additional Information:This work was supported by Ethio-Belgium VLIR Project (grant No. ZEIN2006PR324), GALVmed, Robert S. McNamara Fellowships Program (RSM) of the World Bank and the thematic research project ‘Animal Health Improvement’ of Addis Ababa University.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:McCulloch, Professor Richard
Authors: Dagnachew, S., Terefe, G., Abebe, G., Barry, D., McCulloch, R., and Goddeeris, B.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:Acta Tropica
Publisher:Elsevier
ISSN:0001-706X
ISSN (Online):1873-6254
Published Online:16 March 2015

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