The association of sub-clinical paratuberculosis with the fertility of Greek dairy ewes and goats varies with parity P. Kostoulas a, * , L. Leontides a , C. Billinis b , G.S. Amiridis c , M. Florou a a Laboratory of Epidemiology, Biostatistics and Animal Health Economics, School of Veterinary Medicine, University of Thessaly, 224 Trikalon st., 43100 Karditsa, Greece b Laboratory of Microbiology and Parasitology, School of Veterinary Medicine, University of Thessaly, 224 Trikalon st., 43100 Karditsa, Greece c Department of Obstetrics and Reproduction, School of Veterinary Medicine, University of Thessaly, 224 Trikalon st., 43100 Karditsa, Greece Received 26 April 2005; received in revised form 7 November 2005; accepted 2 December 2005 Abstract Our cross-sectional study investigated the association of sub-clinical Mycobacterium avium subsp. paratuberculosis (MAP) infection with failing to produce a live offspring the season of lambing/kidding (November 2001 to January 2002) before testing (in April–May 2002), in four dairy-sheep and/or goat flocks in Greece (369 animals 1.5-year-old). From each selected animal 10 ml of blood and 10 g of feces from the rectum were obtained. The harvested sera were tested for antibodies to MAP with a commercial ELISA test kit; the feces were cultured on Herrold’s egg-yolk medium supplemented with mycobactin J and antibiotics. An animal was considered sub-clinically infected when found either seropositive or culture positive. The true prevalence of sub-clinically infected animals, adjusted for the sensitivity and specificity of the parallel testing, was 14% (0.1– 28%) and 35.9% (9.2–62.7%) in sheep and goats, respectively. The association of fertility of sheep and goats with sub-clinical paratuberculosis was investigated in random-effects logistic models. Sub- www.elsevier.com/locate/prevetmed Preventive Veterinary Medicine 74 (2006) 226–238 * Corresponding author. Tel.: +30 24410 66092; fax: +30 24410 66047. E-mail address: pkost@vet.uth.gr (P. Kostoulas). 0167-5877/$ – see front matter # 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.prevetmed.2005.12.001