Vaccination can reduce bTB levels in badgers
VACCINATION can significantly reduce bovine TB (bTB) levels in badgers, newly-published research has indicated.
In a four-year study, more than 800 wild badgers in Gloucestershire were captured and injected with the BCG vaccine.
Researchers from the Veterinary Laboratories Agency (VLA) and the Food and Environment Research Agency (Fera) said their study showed a ‘clear effect of vaccination on badger disease’.
But they stressed that, as the blood test is not an absolute indicator of protection from disease, the results do not reveal the degree of BadgerBCG vaccine efficacy. Nor do they provide information on the effect of badger vaccination in reducing TB incidence in cattle.
The field work followed laboratory studies with captive badgers, which had demonstrated that vaccination with BCG ‘significantly reduces the progression, severity and excretion of Mycobacterium bovis infection’
The studies were carried to provide supporting data for the licensing of the Badger BCG vaccine, which was approved by the Veterinary Medicines Directorate in March this year.
A scientific paper summarising the results of the research has been accepted for publication by the scientific journal Proceedings of the Royal Society B (Biological Sciences) and will be published shortly.
Professor Glyn Hewinson, head of the TB Research Group at the VLA, and Professor Robbie McDonald, head of the Wildlife and Emerging Diseases Programme at Fera, said: “In making the data available today, we hope that people will be able to see for themselves the detailed research that went into the development of the vaccine and understand the opportunities and challenges of using vaccination.”
Defra has also published the results of new computer modelling by Fera, which has examined different potential strategies for controlling TB in badgers, including culling and vaccination.
The results were consistent with the conclusions of the Randomised Badger Culling Trial, indicating that there were both positive and negative effects of culling.
The modelling (see box below) showed that badger vaccination could make a ‘positive contribution’ to disease control in its own right and was ‘consistently positive’ when used in combination with culling in a ring vaccination strategy.
The results could prove significant as Ministers develop the Government’s ‘comprehensive’ bTB eradication programme, which they are committed to finalising ‘early in 2011’. A public consultation on Defra’s proposals for badger control, including culling and vaccination, closes on December 8.
The key results of Fera modelling of badger control strategies were:
a) A combined strategy of vaccination in a ring around a culling area was more successful than the cull-only strategy, which in turn was more successful than the vaccination-only strategy, both in reducing the number of TB infected badgers and cattle herd breakdowns. Ring vaccination partly mitigated the detrimental effects of culling. However, the combined strategy requires about twice as much effort than either single approach done in isolation.
b) Culling of badgers should continue for at least four years to realise a clear benefit. However, low rates of land access for culling, or low culling efficiency, or the early cessation of a culling strategy was likely to lead to an overall increase in cattle herd breakdowns (while this is not the case for vaccination).
The results of the research has been published on the Defra website and is available at: http://ww2.defra.gov.uk/food-farm/animals/diseases/tb/