Is Old Brock innocent?

Badgers epitomise the conflicting demands on land use between man and conservation interests. Legally protected and a symbol of wildlife bodies, Old Brock is nevertheless subject to encroachment by developers as well as to culling as part of the controversial cattle TB eradication programme.

These two books contrast the conclusions from the English Ministry of Agriculture, Fisheries and Food, and Irish perspectives. The Badger, comprising the papers from a Dublin seminar, is the first major work on the species in Ireland. It ranges from badger numbers, territoriality, behavioural ecology, and how all these might be employed in relation to the cost-effective management of cattle TB.

Both works may be considered at two levels: the objective data on the badger/cattle link, the research into badger and cattle TB itself; and the rather more subjective way in which this can be interpreted. There is overwhelming epidemiological evidence of a link between badgers and bovine TB, and most of the data in both books reaffirms this. Research in The Badger is updated in Maff's more recent studies such as on the Woodchester population, badger TB modules, possible vaccine, and the tests for both badger and cattle. The latter is given far more prominence by Maff than in earlier reports, and major trials of better blood and DNA tests are underway in Ireland.

The approaches to a badger vaccine are given in both books. The fundamental problem with a vaccine, even if available in 15-20 years' time, will be that cubs catch TB from their mothers, and are unreachable for the first eight weeks of life anyway.

Turning to the subjective interpretation of the TB debate, cattle TB is almost entirely acquired as a respiratory "consumption" of the lungs, just as formerly in human slums, so it is hard to see how badgers might realistically be the cause under field conditions. Maff has admitted that badger guilt is still unproven, and so the badger culls and research is "based on the assumption that badgers do infect cattle" at a cost of £2-3 million a year. As Sherlock Holmes remarked, "when you have eliminated the impossible, whatever remains, however improbable, must be the truth". There is increasing evidence to suggest that badgers have simply been catching TB from cattle.

Tom Hayden's overview conclusions are refreshingly unbiased: "The contribution of the badger (to cattle TB) is unknown and could be zero I the risk posed by badgers, even when confined together with cattle, was low. Quantification of the risk is the major epidemiological blackspot remaining to be solved. Despite misleading comments, the role of the badger in the aetiology of TB in bovines is still not quantified I Little attention has been paid to the possibility that TB in badgers is to some extent dependent on the incidence in bovines."

A fundamental flaw in the whole bovine TB saga is that Maff originally knew in its 1972 Richards Report that "cattle are infective at any stage of the disease I and produce infectious faeces". But now, it is claimed that only cows with gross lung lesions are infectious, which perhaps arises by confusing non-lesion ("tubercles") cases without TB, from early TB cases which are infectious, and are producing TB slurry. Badger TB manifests initially in lymph nodes under the tongue, suggesting it may be picked up via dung beetles from cow pats, which are infectious for up to a year.

The 18th report presents a number of factual points which are hard to explain in terms of badgers. There has been a fivefold increase in TB herds in south-west England's "problem area" from 51 to 4 since 1986. A population boom of tuberculous badgers has been claimed in the press as the cause, but this is countered by the Woodchester study with an unexplained drop in badger TB since 1990. The reappearance of TB in herds clear for some years surely suggests "missed" cattle TB carriers coming into "new areas". Few or no TB badgers were found after such cases initially, but more were later on, suggesting a spillover from cattle to badger.

Proving that cattle do give badgers TB might be a simple, quick and useful contribution to rethinking the cost-effective management of cattle TB, which is after all the object of the exercise.

Martin Hancox is a former member of the Government's consultative panel on badgers and TB.