Epidemiological studies into the role of serogroup-specific vaccines to control footrot in sheep.

Project lead: Liz Nabb

Current recommendations for the control of footrot in sheep include vaccination.

Footrot is caused by the Gram-negative anaerobe Dichelobacter nodosus which is classified into ten serogroups; A-I and M based on genetic variation in the fimbriae gene which provides motility and adhesion. There is one commercially available and licensed vaccine for footrot in the UK, Footvax™, containing nine serogroups. Antigenic competition means that as the number of vaccine serogroups increases, the efficacy of the vaccine reduces.

Published peer-reviewed scientific literature has provided evidence that using fewer serogroups of D. nodosus results in fewer clinical cases of disease in comparison to the commercial vaccine.

In Australia, a recently adopted strategy is for farms wishing to vaccinate to submit foot swab samples for determination of the footrot serogroups present in their flock. Once established, vaccine is provided containing a single serogroup found in that flock. Up to two serogroup vaccines are used concurrently.

The aim of the project is to establish if targeted serogroup vaccination is more efficacious than the commercially available vaccine in reducing footrot prevalence in the UK. A more effective vaccination strategy would lead to reduced reliance on antibiotics for the treatment of footrot, and a positive outcome for sheep welfare.