Authors

CF Obi¹; IO Ezeh¹; MI Okpala¹; A Onyeabo²; RC Ezeokonkwo¹;  ¹ University of Nigeria, Nsukka, Nigeria;  ² Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria

Discussion

African trypanosomosis is an important wasting and an endemic protozoan disease-causing morbidities and mortalities in humans and animals in sub-Saharan Africa. Currently, chemotherapy is the widely practised African trypanosomosis control method in dogs. However, their efficacy is threatened by the emergence of drug-resistant trypanosomes owing to extensive use and misuse over several decades. Thus, this study focused on the sensitivity of Trypanosoma sp. isolated from dogs in Southeastern Nigeria to trypanocides. Trypanosoma brucei (n = 44) and T. congolense (n = 4) isolated from naturally infected dogs in Southeastern Nigeria, between January and August 2016 were subjected to single-dose tests to assess their sensitivity to trypanocides - diminazene aceturate (DA) and isometamidium chloride (ISM). Subsequently, DA and multidrug-resistant isolates were further subjected to DA multi-dose test and CD50 was determined. Clones were derived from a randomly selected multidrug-resistant isolate and their sensitivity was also assessed. 100% and 83.3% of T. congolense and T. brucei respectively were resistant to the trypanocides. Amongst the drug-resistant isolates, 50%, 16.7% and 33.3% were resistant to DA, ISM and both trypanocides respectively with CD50 ranging between 14.26 – 34.69 mg/kg. Drug-resistant trypanosomes were characterized into highly resistant (CD50 = 11–24.99 mg/kg) and very highly resistant (CD50 = >25 mg/kg) trypanosome isolates. Clones also expressed high levels of resistance to both DA and ISM with CD50 values between 35.19 and 37.19 mg/kg. Trypanocidal resistance was thus, confirmed and appears to be widespread in dogs in Southeastern Nigeria. The adoption of an integrated trypanosomosis control strategy is most desirous.