Please cite this article in press as: Mederos, A., et al., A systematic review-meta-analysis of primary research investigating the effect of selected alternative treatments on gastrointestinal nematodes in sheep under field conditions. PREVET (2011), doi:10.1016/j.prevetmed.2011.10.012 ARTICLE IN PRESS G Model PREVET-3059; No. of Pages 14 Preventive Veterinary Medicine xxx (2011) xxx–xxx Contents lists available at SciVerse ScienceDirect Preventive Veterinary Medicine j ourna l ho me pag e: ww w.elsevi er.com/locate/prev etmed Review A systematic review-meta-analysis of primary research investigating the effect of selected alternative treatments on gastrointestinal nematodes in sheep under field conditions A. Mederos a,b,∗ , L. Waddell b,e , J. Sánchez c , D. Kelton b , A.S. Peregrine d , P. Menzies b , J. VanLeeuwen c , A. Raji ´ c e a National Research Institute for Agriculture, Uruguay. Ruta 5 km 386, Tacuarembo 45000, Uruguay b Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Canada N1G 2W1 c Department of Health Management, Atlantic Veterinary College, University of PEI, 550 University Avenue, Charlottetown PEI, Canada C1A 4P3 d Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Canada N1G 2W1 e Laboratory for Foodborne Zoonoses, Public Health Agency of Canada, Guelph, Ontario, Canada a r t i c l e i n f o Article history: Received 18 August 2011 Received in revised form 27 October 2011 Accepted 30 October 2011 Keywords: Systematic review Meta-analysis Sheep Gastrointestinal nematodes Control methods Alternative treatments a b s t r a c t Selected alternative treatments for preventing or controlling gastrointestinal nematodes (GIN) in sheep under field conditions were evaluated using a systematic review-meta- analysis methodology. Forty-three publications reporting 51 studies (21 controlled studies (CS) and 30 challenge studies (ChS)) and 85 unique treatment comparisons were included in the review. The alternative treatment categories were nutraceuticals (28 studies), breeding for genetic resistance (12), nutritional manipulation (6), homeopathies (2), administration of copper oxide wire particles (2), and biological control (1). Random effect meta-analyses (MA) and meta-regression were performed with the natu- ral logarithm of the difference in means (ln MD) between the control and treatment groups, for fecal egg counts per gram of wet feces (FEC), worm counts (WC) or fecal egg counts per gram of dry matter (FECDM) as the outcome. Treatment effect estimates (ln MD) were back- transformed to their count ratios (CR), a relative measure of effect for controlled versus treated groups, for presentation of results. Significant heterogeneity was observed for both CS and ChS that evaluated nutraceuticals, genetic resistance and nutrition treatments. MA of ChS that investigated nutraceuticals resulted in a significant overall CR of 1.62 (P < 0.01) and 1.64 (P < 0.01) for FEC and FECDM, respectively and a marginal significant CR of 1.14 (P = 0.06) for WC, all favoring the treated groups. MA of CS and ChS that investi- gated genetic resistance resulted in a significant overall CR of 5.89 and 15.42, respectively (P < 0.01), again favoring treated groups. MA of CS that investigated homeopathies with FEC as an outcome were homogenous (I 2 = 0.0%) and resulted in a non-significant pooled CR of 1.61. ChS investigating copper oxide wire particle treatments and WC as an outcome, were homogenous (I 2 = 0.0%) and had a marginally significant pooled CR of 1.68 (P = 0.06). Publication bias was observed for ChS with WC outcomes, indicating that small size studies reporting non-significant CR, were less likely to be published than similar stud- ies that found a significant CR. In a meta-regression, randomization (6.2%) and study size (29.2%) were the main factors contributing to the total variation when the outcome was FEC, ∗ Corresponding author at: National Research Institute for Agriculture, Uruguay. Ruta 5 km 386, Tacuarembo 45000, Uruguay. Tel.: +598 4632 2407; fax: +598 4632 3969. E-mail address: amederos@inia.org.uy (A. Mederos). 0167-5877/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.prevetmed.2011.10.012