The role of serogroup specific vaccination in the control of footrot in sheep (PhD - MIBPT iCASE)

The challenge

Footrot is a welfare issue. Reduced productivity and the cost of treatment also make it an economic issue for the sheep industry. A footrot vaccine, Footvax, has been licensed here for some years, yet has failed to make an impact on the disease. Footrot is still present in over 90% of English flocks and remains the main cause of foot disease.

Footrot is caused by the bacterium Dichelobacter nodosus. Nine different serogroups of D.nodosus have been found in English flocks, and Footvax contains all of them. Flocks may have a range of D.nodosus serogroups, but typically only have two or three.

As the number of serogroups contained within a footrot vaccine increases, the protective immunity drops. This is known as antigenic competition. Studies in Australia have shown that vaccinating against only two of the serogroups present at a time has a much greater impact in reducing cases of footrot.

About this work

The aim of this project is to find out if the same strategy of targeting only two serogroups is effective in the control of footrot in English flocks. The mild, damp climate together with the structure and movements within the sheep industry make conditions very challenging for footrot control compared to the places this strategy has been successful so far.

We will first screen farms to establish which serogroups are present, then vaccinate against two of them. We will compare the number of lameness and footrot cases in the vaccinated group to sheep receiving Footvax, or no vaccine. We will sample footrot cases to monitor how the distribution of the serogroups changes in the flock. If the vaccination strategy is successful we will calculate the cost benefit and how much antibiotic could be saved across the industry.

The student

Liz Nabb, University of Birmingham

Watch Liz's video about her PhD on our AHDB Beef & Lamb YouTube channel https://youtu.be/KwyA0c07EGc