Transmission parameters of Mycobacterium avium subspecies paratuberculosis infections in a dairy herd going through a control program A. Benedictus a, * , R.M. Mitchell c , M. Linde-Widmann b , R. Sweeney b , T. Fyock b , Y.H. Schukken c , R.H. Whitlock b a Utrecht University, Faculty of Veterinary Medicine, Department of Farm Animal Health, Yalelaan 7, 3584 CL Utrecht, The Netherlands b New Bolton Center, University of Pennsylvania, 382 West Street Road, Kennett Square, PA 19348, USA c Quality Milk Production Services, Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA Received 30 August 2006; received in revised form 3 July 2007; accepted 24 July 2007 Abstract A Johne’s disease control program, including stringent management practices and a test-and-cull program (whole-herd fecal-samples taken twice a year), was implemented on a medium-sized Pennsylvania dairy farm that was suffering losses from clinical Johne’s disease. The data that emerged from the control program, combined with birthdates, culling dates, lactation information and pedigrees, yielded an extensive longitudinal dataset. The dataset was processed through SAS 9.1 for statistical analysis; herd-level disease dynamics and dam-to-daughter transmission parameters were calculated. After the implementation of the program in 1984, prevalence dropped dramatically from 60% to less than 20% in 1989. After an apparent prevalence peak (25%) in 1991 due to improved test sensitivity, prevalence maintained a plateau of 10% from 1996 to 2000. After the implementation of the program, 9.5% of the offspring from test-negative dams and 26.8% of the offspring from known-infected dams became infected with Mycobacterium avium subspecies paratuberculosis (Map) (x 2 = 14.7; p = 0.0001). Calves born shortly following the calving of an infected dam and calves growing up with a future high shedder were more likely to be infected compared to calves without this risk profile. It was concluded that, after the implementation of the control program, the most important causes of infections of susceptible calves were their own dams or infected animals which had calved recently. # 2007 Elsevier B.V. All rights reserved. Keywords: Mycobacterium avium subsp. paratuberculosis; Johne’s disease; Paratuberculosis; Epidemiology; Control programs www.elsevier.com/locate/prevetmed Preventive Veterinary Medicine 83 (2008) 215–227 * Corresponding author. Current address: Maliesingel 58, 3581 BR Utrecht, The Netherlands. Tel.: +31 616483634. E-mail address: a.benedictus@gmail.com (A. Benedictus). 0167-5877/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.prevetmed.2007.07.008