Badgers: Bovine Tuberculosis

Lord Trees Excerpts

Monday 9th December 2013 Grand Committee

[Lord Trees (CB)]

My Lords, I, too, thank the noble Lord, Lord Knight, for bringing this subject forward for debate. I want to try to look at the problem rather holistically, which is a challenge in under 10 minutes, but I will try. Let us be under no illusions: bovine tuberculosis is a major threat to the health of domestic animals and wildlife in Britain today. This is a disease that was almost eradicated from Britain 40 to 50 years ago by means, directed at cattle, that were essentially the same as those we use now—TB testing of cattle and the removal of reactors, although a good many other measures have been put in place that mean that the controls on cattle are even tighter than they were then. A key factor that has changed in the past few decades is the emergence of badgers as a major wildlife reservoir of this infection. There is epidemiological evidence that something like 50% of outbreaks in cattle are related to badger infections.

We are faced now with a problem of infection in badgers and in cattle on a substantial and increasing scale. If I could show the Committee maps of the spread of the infection, noble Lords would see that there has been a relentless spread in the geographical distribution of bovine infection from the original hotspot in the south-west of England, when it was nearly eradicated, to the current situation where bovine TB is threatening the dense cattle populations of Cheshire and Lancashire.

Although there is an understandable focus on the adverse impact on cattle and badger health and welfare, we should not forget that there is another victim of this disease—the cattle farmer who suffers huge stress and distress every time their herd is tested and animals are removed from the herds that they have built up over many years. We do not concern ourselves enough with the human toll that this disease is having. It is a fact that the suicide rate in farmers is the highest of any professional group. Although one certainly cannot claim that this is all due to TB, the fact is that an already vulnerable group of people is being subjected to excessive anxiety and uncertainty. That is the situation that we are facing. When the average city dweller pours their milk over their cornflakes each morning, they may not understand the hard work, worry and commitment that go into producing that daily milk.

What are the options to deal with this disease? Ideally, an effective vaccine for cattle is the solution but for various reasons, which have been made clear most recently by a letter from the EU Commissioner Tonio Borg, it is likely to be some 10 years before a vaccine is accepted and licensed in the EU to be deployed in the UK. Experience shows that in the absence of a vaccine for the target domestic species—in this case, cattle—and where there is a wildlife reservoir of infection, control measures need to address the wildlife reservoir as well as the domestic animal. In the case of bovine TB, there is a wildlife host, the badger, that is present in very high numbers—10 to 15 setts on a farm is not unusual—is in close direct and indirect contact with cattle on grazing areas, in forage crops such as maize and indeed in farm buildings, has no natural predators and is excreting substantial amounts of Mycobacterium bovis into the environment. In this situation, and in the absence of a cattle vaccine, measures directed at the wildlife host, as noble Lords who spoke earlier accepted, are essential as well as stringent measures directed towards cattle.

What are the options vis-à-vis badgers? As your Lordships are aware and as has been mentioned, a vaccine for badgers is licensed for use by injection. It has various limitations, including the fact that a high coverage of the population is necessary to reduce infection and transmission. Something over 40% has been suggested, which is feasible but difficult in a wild animal population compared with a controlled domestic animal population. Animals that are already infected will not be stopped by vaccination from excreting bacteria, and susceptible young animals are constantly being born into the population. Moreover, the animals have to be cage-trapped and restrained to allow injection—itself a stressful procedure for a wild animal. This is one rational approach, and it was advocated by noble Lords who spoke earlier, but it has to be said that the effect on bovine TB incidence is unproven. It is also a very costly measure, as things stand. The current vaccination trial in Wales, which has completed two years, shows that it costs more than £600 to vaccinate each badger. With a population of probably 250,000 to 300,000 badgers in Britain, you need only do the mathematics to determine the cost of vaccinating at least even a proportion of that population.

Still, if interested parties could work together effectively and economically to deliver a vaccine, that would be hugely helpful and doubtless the cost could be reduced. It would require a co-ordinated approach by many different groups, including those working in conservation. In that context, the Welsh Government have offered grant support to private groups to subsidise the cost of vaccination by 50%, and certain conservation groups are seriously considering that option. It is regrettable, however, that so far neither the RSPCA nor the Badger Trust has taken up the invitation to commit funds to achieve badger vaccination.

[The Duke of Montrose (Con)]

I am most grateful to the noble Lord for giving way. Can he help the Committee by telling us at what age young badgers catch TB and at what age they can be vaccinated?

[Lord Trees]

I am not sure whether the data are available but they may be. I am sorry that I cannot answer the question; I would hate to do so without preparation.

The dynamics of infectious disease in general show that reducing the density of the population will reduce infection transmission. This does not require the complete elimination of a population—far from it. However, if the population density is lowered so that the rate at which a primary infection creates secondary infections falls below 1, the so-called parameter R₀—the reproductive rate—the infection will subside. We know that in a number of areas the R₀ for bovine TB is only fractionally greater than 1; in fact, estimates range between 1 and 1.2. Reducing that to less than 1 may be achievable with modest reductions in the badger population.

The use of contraception is a possibility to reduce badger-population density and would be a humane way of doing so, but research is at an early stage. I am told that it will be some years before we might have a deployable contraceptive method. As well as contributing to the control of bovine TB, a reduction in the badger population would benefit other species that appear to be adversely affected by predation by badgers, such as hedgehogs, ground-nesting birds and some rare species of bumblebee.

That brings me to culling. This has been used to reduce many wild animal populations, including badgers, in various circumstances. We currently cull deer, foxes, grey squirrels, seals, magpies and rodents, among others. No one likes killing animals—I certainly do not—but the majority of us accept that culling animals in certain circumstances is justified, provided always that it is done humanely. Members of this House are complicit in the extermination of rodents within these very walls.

If the culling of badgers can be done humanely and with a sound scientific basis, ruling it out at this stage as one of the tools in the control of bovine TB is premature. As the noble Baroness, Lady Parminter, has said, we need to see the report of the independent expert panel on the current trials to evaluate their humaneness and safety, and to understand why the culling rate was less than intended and what factors were responsible for it. As the noble Lord, Lord Krebs, mentioned, a key meeting of experts in 2011 accepted that a reduction in TB incidence of around 16% could be achieved by culling badgers under certain circumstances, and that included allowing for the perturbation effect. One may think that 16% may not sound a huge amount, but if the infection rates from badger to badger, badgers to cattle and cattle to cattle can be reduced by just a relatively small amount so that the infection parameter R₀ can be tipped below 1, the disease will be driven to extinction, which is a goal that we all seek.