Poster Presentation MedVetPATHOGENS 2018

A national cohort study of the serological diversity of Dichelobacter nodosus in sheep in sickness and in health (#83)

Naomi S Prosser 1 , Kevin J Purdy 1 , Laura E Green 1
  1. School of Life Sciences, The University of Warwick, Coventry, United Kingdom

Ovine footrot is caused by Dichelobacter nodosus and has two clinical presentations: interdigital dermatitis and severe footrot. Footrot is endemic in the UK, affecting almost all flocks. Footrot lesions are painful and the disease has been estimated to cost the UK sheep industry £80 million per annum. There are ten serogroups of D. nodosus and in the UK there is one licenced multivalent vaccine targeted at nine of the serogroups. It has limited efficacy, possibly due to antigenic competition between serogroups, and reduces lameness by approximately 20%. Autogenous mono/bivalent vaccines are more effective. The objective of this study is to investigate the diversity and distribution of the serogroups of D. nodosus on the feet of sheep in flocks throughout England. In 2016, 164 farmers were recruited from across England. These farmers had completed detailed questionnaires on lameness in 2013 and 2014.  In 2016 they completed a shorter questionnaire on lameness management and provided up to eight swabs from the interdigital skin of feet from sheep in their flock. A total of 1,288 interdigital swabs were collected: 75% from footrot-affected feet, 12% from non-footrot diseased feet, 7% from healthy feet and 7% from feet with an unknown lesion status. DNA was extracted from the swabs and PCR was used to investigate the serogroups (A-I) present on the 687 (53.3%) D. nodosus-positive feet. Of the D. nodosus-positive feet, 82% were footrot-affected, 9% were non-footrot diseased and 3% were healthy. Up to four serogroups per foot and six serogroups per flock were detected. Serogroups H and B were most commonly detected, on ~35% of feet and ~67% of flocks each. The least commonly detected serogroup, F, was detected on 1.0% and 2.6% of feet and flocks respectively. Further work on the geographical distribution and management associations with presence of serogroups is ongoing.