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

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 (< or = 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.