A Study on Trypanocidal Drug Resistance: A Risk on Animal Health and Production in Jawi District of North West Ethiopia

Abstract

The study was conducted from February to June, 2021, with the objective to assess the occurrence of trypanocidal drug resistance in naturally infected bos indicus breed of cattle in hot spot villages of Jawi district, North Western Ethiopia. An initial cross-sectional prevalence study was conducted in four villages with the aim of finding at least 10% trypanosome parasite prevalence for further longitudinal drug susceptibility trial. Accordingly, out of 464 cattle examined from all villages, 53 (11.4%) animals were trypanosome-positive using a Buffy coat test method. For the appropriateness of monitoring and follow up of animals subjected to drug susceptibility trial and on the basis of village’s adjacency, the areas were merged in two sites (i.e. Achari and Kurey peasant associations). A 28-day field protocol study was used to estimate proportion of resistance to a recommended dose of 0.5 mg/kg Body Weight (bw) for Isometamidium Chloride (ISM) and 3.5mg/kg bw for Diminazene Aceturate (DIM). In this study, 52 trypanosome positive cattle were ear-tagged and allocated into two treatment groups. Group I, which consists 27 animals was treated with 7% solution of 3.5mg/kg bw DIM and the second group having 25 animals were subjected to 1% solution of 0.5 mg/kg bw ISM with 25 trypanosome free animals as a control. Before the actual treatment begin all animals grouped under treatment and control groups were subjected to deltamethrin 1% pour-on at day 0 on the animals back midline. Animals under trial were monitored for the status of trypanosomes and Packed Cell Volume (PCV) levels on days 14 and 28 post treatment. A treatment failure rate of 40% (10/25) forcattle’s treated with ISM was observed on day 28; whereas, 48.1% (13/27) DA treated animals on day 14 post-treatments were failed to clear the parasites. The results of the study confirmed the presence of drug resistance to the maximum recommended doses of ISM and DIM in the study district. Of all ISM and DIM treatment failures T. congolense accounted for 77.8% (7/9), 53.8% (7/13)); T. vivax (0%, 20%) and T. teleri (100%, 100%) respectively. Drug resistance has indeed been a considerable threat in each village of the study sites. DIM treated trypanosomepositive cattle showed a significantly increased (p < 0.001) PCV% from 19.9 % at day 0 to 21.2 % at day 14 and eventually to 23.8% at day 28. Similarly, ISM treated animals considerably increased (p<0.001) PCV% from 21.5% at day 0 to 23.9% at day 14 and then to 25.0% at day 28. However, the PCV% value for the negative control has no statistical variation (p=0.662) among the various days under investigation. Rational use of trypanocidal drugs and control of co-infections to exploit self-cure against resistant trypanosome populations are recommended. Furthermore, further study using advanced molecular techniques to explore possible pathways on development of drug resistance could be necessary.