Jonnie Yewdall appointed Commercial Director by developers of accurate Actiphage diagnostic  

Jonnie Yewdall, a former dairy farmer, has been appointed Commercial Director at PBD Biotech. The company recently gained funding to take its Actiphage® blood test for bovine TB (bTB) and Johne’s Disease through the validation required for international industry acceptance.

Jonnie has worked in a commercial role in other industries, but he knows first-hand the devastating impact bTB and Johne’s disease can have on farmers through his experiences on a family farm in North Devon, where the herd was decimated by these diseases.

He lost a third of his Guernsey herd following a positive bTB test, and then the replacement animals began to show signs of Johne’s Disease, another mycobacterial disease. Unfortunately, this was the final straw. The emotional toil and the ongoing financial loss were too great and the Yewdalls sold the family farm.

Jonnie says: “I think that Covid-19 has shown the wider business community what it is like to be a dairy farmer at risk from bTB – you are locked-down and you can’t plan or budget.

“I don’t want any farmers to go through what we did, which is why I have joined PBD Biotech. With tools like Actiphage the industry has an opportunity to work together to potentially eradicate these very difficult diseases.”

Actiphage is an extremely specific test, as it detects the DNA from live bacteria in a sample of blood or milk, not just the animal’s immune reaction. It can detect just a few cells; this enables farmers to identify carriers of the disease and remove them from the herd before they become spreaders. This was a recent recommendation from the cattle health certification standards regulatory body Checs.

Actiphage has been approved by APHA for use under special conditions, and when used on-farm as part of a disease management programme it has been proven to eradicate bovine TB.

By recently gaining £2.3M of funding, PBD Biotech is now able to take Actiphage through trials to gain OIE (the World Organisation for Animal Health) validation for the test which will enable international acceptance.

Jonnie sees potential for Actiphage to be used as part of a wider disease management programme to enable farmers to eradicate and then maintain a disease-free status on the farm.

“Actiphage is a blood test for live mycobacteria that gives you a simple yes/no answer. When this is authorised for use on the farm, we could use it in parallel with the statutory testing to manage the infection risk, for example isolating inconclusive reactors pending a further skin test,” he says.

“It could be used as a ‘pre-movement’ test to check animals before they are introduced into a herd and also as a ‘DIVA’ test to differentiate infected from vaccinated animals, paving the way for the introduction of a vaccination programme.”

Jonnie will be talking about his experiences and development of the Actiphage test at the Agri-TechE event ‘Heartbreak and hope – the story of a new diagnostic for bovine TB’ on Tuesday 6th July 2021, from 10am-11am. Find out more at