Epidemiology of Eimeria infections in an Austrian milking sheep flock and control with diclazuril

Abstract

In a flock of milking sheep from Styria (Austria), the dynamics of Eimeria oocyst excretion was monitored in the lambing season 2003–2004 and a treatment trial with 1 mg/kg diclazuril (single dose on day 0 of study) was conducted in two groups of early weaned lambs. Adult animals ( n = 30 ewes, 30 yearlings) excreted oocysts of different species (weekly prevalences from week −7 ante partum to week 5 post-partum: ewes 20–60%, yearlings 38–73%) in low intensities (≤6000 oocyst per gram of faeces, highest values in weeks −1 and −4) without clinical signs. Ewes excreted significantly fewer oocysts than yearlings. Lambs in the first group ( n = 32 treated animals, 32 controls) excreted oocysts from the seventh day of sampling (average age on day 0: 28 days), those in the consecutive group ( n = 32 treated animals, 30 controls) already excreted oocysts on day 0 (average age: 34 days). Treatment resulted in significant reduction of the overall excretion rates on days 7–21 of study compared with untreated controls. Similarly, the excretion intensities were significantly reduced in the treated groups. Overall excretion rates of the pathogenic species ( Eimeria ovinoidalis, Eimeria bakuensis, Eimeria weybridgensis/ Eimeria crandallis, Eimeria ahsata) were significantly reduced after treatment. Soft faeces and anal soiling in the lambs were significantly reduced and weight gain was increased. A single treatment of lambs with diclazuril before or shortly after the onset of oocyst shedding was sufficient to control oocyst excretion and improve animal health.