Bovine TB and Johne’s Disease are two devastating livestock diseases and control has been limited by the lack of accurate diagnostics. In the 2018 Innovation Hub, PBD Biotech announced the development of Actiphage®, an accurate and specific blood test that offers hope for eradicating Bovine TB.
Diagnostic testing is strictly regulated and Actiphage has gained approval from the APHA for use as a non-validated test for use in herds with a chronic breakdown. PBD Biotech has recently gained funding to take it through World Organisation for Animal Health (OIE) validation.
Control of Bovine TB
This news has been well received by farmers and vets as it will give them a tool to use within an effective disease management programme
“From an industry perspective bovine tuberculosis is a huge problem – the disease continues to move across the UK, and we don’t appear to be getting on top of it. We need many more tools in the toolbox in order to help us manage and eradicate this disease,” says David Christensen of Kingston Hill Farm Ltd, a family-owned farming company operating dairy and beef farming enterprises in the Thames Valley, to the west of Oxford. He has a herd of 2,000 animals.
Christensen is concerned about the failure of the industry to control and eradicate bovine tuberculosis (bTB). He says: “There is a combination of factors, but a key challenge is a lack of decent testing of the animals in our herds. The current tests are unable to accurately identify those at an early stage of the disease, before they become infectious, so that they can be removed.
“The other main concern is the lack of a vaccine. I am proactive about herd health and vaccinate my cattle against a range of other diseases, so if there was an effective vaccine for bovine TB I would use it.”
Actiphage® is a new rapid blood or milk test for the mycobacteria that cause bovine TB, Johne’s Disease and human TB. It identifies live mycobacteria and so can distinguish between vaccinated and infected animals, a pre-requisite for a vaccine. It is currently going through trials to take it through to OIE validation.
Christensen welcomes this development: “I welcome the diversity of tests coming forward – although I’m no expert, I expect they will all have a role in some capacity – the more we’ve got, the better because then we can tailor the tools to each on-farm situation.”
The official skin test measures the immune response that develops after an animal has been exposed to bTB. This response takes time to develop and it is known that up an average of 20-25% of TB-infected cattle can be missed by one round of skin testing using standard interpretation – leaving a reservoir of disease in the herd.
Eradicating Bovine TB
Actiphage can be used to retest those animals where there has been some reaction to the skin test but not sufficient for them to be classified as positive and culled. Christensen sees promise in this approach.
“We’ve had animals that are not officially inconclusive but there’s been some bovine TB reaction. We’ve used Actiphage to test those animals, and then made a decision about the animals based on those results.
“Actiphage told us that those animals were carrying bTB, so those animals were then removed from the herd.
“However, the problem at the moment is that if you use Actiphage to make the decision to cull then you don’t get any compensation – so we lost the value of the cows.”
The hope within the industry is that through validation by OIE it will be possible to use Actiphage in parallel with other tests, to increase knowledge about the disease.
Christensen continues: “With better information about the progression of the disease it might be possible to develop a management strategy based on the information that a test can give. For instance, we could proactively remove animals before they became infectious and thus reduce the overall disease pressure in the herd – but all that is yet to be proven, which is why the validation is so important.
“Another unknown is the risk to the calves of cows that have tested positive. An accurate and reliable diagnostic would allow us to test the offspring from TB reactors and see if they were carrying the disease. With more information you could develop a strategy – perhaps to use through targeted application with certain animals to get greater information about their TB status.”
PBD Biotech are participating in the Agri-TechE express meeting ‘Heartbreak and hope – the story of a new diagnostic for bovine TB’ on Tuesday 6th July from 10-11 am.