“Vaccination is no silver bullet against TB – DEFRA’s policy is wrong and will ultimately backfire,” said Dr Zellweger.
The golden rules of vaccination for any disease are to never vaccinate a stressed or weakened animal or an animal that may already be infected with the disease. Ignoring these basic principles will have severe implications in terms of disease spread, he said.
“The current English policy will heighten the risk of disease spread,” said Dr Zellweger. “Catching and trapping badgers to vaccinate them will cause huge stress to the animal.
“This not only has implications in terms of immuno-suppression, but will ultimately lead to perturbation.”
Badgers live in social groups. After trapping, a badger will be weakened and stressed which could effect its position within the social structure. As a result they may be expelled from the sett.
“These weak badgers will move to a neighbouring sett to try and find an alternative dwelling. This in itself will cause fighting, encouraging the spread of TB between animals.
“Weak animals will also try and find a convenient feed source, usually farmyards or feed troughs – yet again leading to more disease spread.”
Vaccinating all badgers can also increase disease shedding. “If we vaccinate an animal that may be harbouring TB in a ‘closed’ or inactive form, the vaccine can promote the ‘closed’ bacteria to an ‘open’ form.” Open lesions can spread billions of bacteria in a number of days.
But it is impossible to tell if a seemingly healthy badger is infected with the “closed” form of TB without doing blood or skin tests.
“If we were to blood- or skin-test before vaccinating, the badger would have to be held for several days before the results came back. This would create more stress to the badger and would obviously not be practical.”
We must also question the effectiveness of the vaccine, said Dr Zellweger. “The BCG vaccine has been used for years in vaccinating healthy children. Even when done properly there are questions over efficiency.”
The way in which vaccination will be prescribed is also a significant issue. “The TB vaccine can only be used under prescription. The question is who is going to do this and who is going to be liable? As a vet, I am not happy prescribing such a vaccine.”
Dr Zellweger was involved in the highly successful TB eradication programme in Switzerland. “In my home country, TB was eradicated by isolating and closing down all reservoirs of TB. This included both badgers and cows.”
“There is a point in vaccinating badgers, but only once all sources of TB have been located and culled. Only once TB has been eradicated should vaccination be considered.”
Hilary Benn’s badger vaccination policy will come into effect in 2010, with oral bait potentially available by 2014. “DEFRA’s policies have lost contact with the countryside,” said Dr Zellweger. “Ultimatley this will lead to the spread of TB throughout the country.”