Study on the assessment of drug resistance on Trypanosoma vivax in Tselemti woreda , Tigray, Ethiopia

Abstract

The study was conducted at Tselemti Woreda, Tigray region, Northern Ethiopia, some 1200 kms away from the capital, from November 2002 to April 2003. In the first phase of this study, questionnaire survey was carried out to assess livestock production constraints. Subsequently, a study on the occurrence of drug resistance to diminazene aceturate and isomethamidum chloride of Trypanosoma vivax isolate in artificially infected goats were conducted. Results of the questionnaire survey revealed that 95.7% of the interviewees replied that trypanosomosis is a series problem in their areas. Apart from this, under dosing of trypanocidal drugs appeared a common practice in the areas surveyed. Drug sensitivity test conducted on 18 artificially infected goats revealed that T. vivax developed resistance to the curative doses of diminazene aceturate (3.5 mg/kg b.wt) and isomethamidum chloride (0.25 mg/kg b.wt). No relapses were seen for those animals treated with diminazen aceturate at a dose of 7 mg/kg b.wt and 0.5 mg/kg b.wt of isomethamidum chloride. Sanative pair between diminazene aceturate and isometamidum chloride was also confirmed by the occurrence of no relapses after first treatment with diminazene aceturate (at 3.5 mg/kg) and isomethamidum chloride (0.25 mg/kg) and a second treatment with 0.25 mg/kg isomethamidum chloride and 3.5 mg/kg diminazene aceturate, respectively. During the 90 days of trial period there was no statistical significant difference (P>0.05) in mean PCV of the five groups before and after treatment: (26+1.23), (27.5+1.33), (26.5+2.03), (29.8+2.12) and (25.5+ 3.06) for groups I, II, III, IV and V respectively. Generally diminazene aceturate at dose of 7 mg/kg and isomethamidum chloride at dose of 0.5 mg/kg b.wt were most effective in terms of curing infections as well as improving PCV and body weight. It was concluded that where there are indications for drug resistance against isomethamidum and diminazene aceturate the use of trypanocidal drugs should be supervised, the principle of sanative pairs has to be applied and chemotherapy needs to be integrated with other methods like vector (tsetse and biting flies) control.

Keywords: Diminazene-aceturate, drug-resistance, goats, isomethamidumchloride, trypanosomosis, Tselemti.