Abstract

Merino sheep in the Mountain Kingdom of Lesotho are infested by ticks. Sheep production system in Lesotho is mainly by extensive and communal management system. This type of management system can predispose sheep to cross-infestation of ticks. Therefore, this study was designed with the following objectives; to determine farmers’ educational level in relation to their awareness of ticks’ infestation in their flocks, to determine the prevalence of tick genera in each of the four agro-ecological zones (AEZs) and to determine the efficacy of ivermectin (1%) in controlling each tick genus. Four hundred and three (403) respondents (sheep farmers) were interviewed. Seven hundred and twenty sheep were examined for the prevalence of ticks. These ticks were identified in the laboratory using taxonomic keys with the aid of a stereoscope. The longitudinal GEE logistic regression was used to analyse the data for ticks’ prevalence to ascertain the effect of AEZ, age and ivermectin (1%) efficacy on ticks’ infestation. Data on ticks’ concentration was analysed by Poisson model. The results indicated that there was a significant (p 0.05) between AEZs whereas more sheep farmers were married (P < 0.05) in all the four AEZs. There were more sheep farmers (P < 0.05) with small flock size of 1-10 than medium (20-50) and large (50+). The results further indicated that the Rhipicephalus’ population in all four AEZs was 36% while the other species were relatively non-existent (> 1%); farmers’ education level is very low (primary school certificate) and their awareness of the menace of ticks in their flocks is also very low; Rhipicephalus tick genus is the most prevalent and the overall efficacy of ivermectin (1%) against Rhipicephalus tick genus at 30, 60 and 90 days after injection were 23.6%, 0% and 0%, respectively.

Key words: Agro-ecological zones, Ivermectin (1%), Merino sheep, Ticks