Prof Rosie Woodroffe: ‘Hard to offer farmers advice’

NEW findings from the Zoological Society of London (ZSL) and Imperial College London suggest that badgers and cattle rarely meet – and that direct contact between the two is not a likely source of transmission of bovine TB. 

The stated aim of the badger culls, which began as pilots intended to trial ‘controlled shooting’ of free running badgers in two areas of South West England, but were expanded to include the more expensive trap-and-shoot and a new cull zone before the initial trial period had finished, was to reduce the ‘wildlife reservoir’ of bovine TB in badgers.

The new research shows that while badgers do favour cattle pasture as a habitat, they typically avoid cattle themselves and rarely get close enough to transmit infection directly. In the study, researchers used GPS collars to track the movements of badgers and cattle across 20 farms in Cornwall. They didn’t find a single incidence of badgers and cattle coming face to face and said that, if anything, badgers tended to avoid larger animals, preferring to keep 50m between themselves and cows.

They said that any bovine TB transmission between the species is likely to come from their shared environment – possibly from infected urine or faeces in pastures, possibly from other cattle as well as badgers – rather than direct contact. Imperial College London researchers said their discovery means advice to farmers on controlling bTB may require a rethink and ‘paves the way for novel approaches to managing this controversial disease’.

BTB HARD TO CONTROL 

The findings could shed light on just why bTB is so hard to control, even when badgers and cattle are being culled, because the bacteria that cause the disease can persist in the environment for months.

Earlier research from the government’s Animal Health and Veterinary Laboratories Agency (AHVLA, now APHA) which used surveillance cameras on 75 farms to look at possible ways of badger-proofing farms captured footage of badgers attempting to access cattle feed in sheds and fields. Defra said its bTB control strategy still includes wildlife-proofing high risk farms.

Discussing the recent findings, Professor Rosie Woodroffe, a senior ZSL researcher and a visiting professor at the School of Public Health at Imperial, who has spoken out against the government’s badger culling policy, said: “It has been known for a long time that badgers can transmit TB to cattle – but without knowing how they do it, it is hard to offer farmers advice on the most promising ways to protect their herds.

“Our study provides the strongest evidence yet that transmission is happening through the environment, helping to explain why controlling TB is so difficult. This work marks the first step towards identifying more effective ways to reduce transmission between badgers and cattle, and also potentially better ways to manage cattle-to-cattle transmission as well.”

It has long been known that badgers can pass bovine TB on to cattle, but an increasing body of research has shown that patterns of infection are very complex – that cattle-to-cattle transmission is the most common source of bTB on farms and that cattle can pass the disease to badgers – and this means badgers’ role in transmitting the disease, which can also affect a host of other wild and domestic species, is unclear.

‘NO CERTAINTY’ 

Speaking to the BBC, Prof Woodroffe said: “There are loads and loads of things that farmers are being advised to do and there is no certainty that any of them will actually work and because of this, hardly any farmers implement any of these sorts of measures. If we can focus on the things most likely to work on that massive array of things farmers are being advised to do, more people will do them.”

The researchers, whose work was funded by Defra, are now scanning fields to see where TB bacteria are present.

Defra is expected to announce that its highly controversial cull will be expanded into new areas of the South-West later this summer.

A COMPLEX DISEASE 

A NFU Cymru spokesperson said: “Bovine TB is a complex disease that must be tackled in the round, including addressing wildlife disease reservoirs, if we are to stand any chance of eradicating the disease. The role played by badgers in the spread of bovine TB is well known and widely accepted. Badgers are recognised as a significant wildlife reservoir of the disease in areas where it is endemic. Research has shown that badgers could contribute to up to 50% of cattle herd TB breakdowns in areas where the disease is rife.

“NFU Cymru has always said that we must use all options available if we are to stand a chance of controlling and eradicating this devastating disease. Cattle movement controls, cattle testing and on-farm biosecurity all have a vital role to play in a TB eradication plan, but experience from across the globe and indeed from our neighbours across the border in England and across the Irish Sea, have shown that a genuine TB eradication plan must also include a strategy for dealing with the disease reservoir in wildlife, in areas where it is endemic.

“From its inception, NFU Cymru has consistently raised concerns about the cost and effectiveness of the Welsh Government’s badger vaccination policy in the Intensive Action Area (IAA) in North Pembrokeshire. Four years in to what was supposed to be a five year programme, a global shortage of the BCG vaccination has led to its premature curtailment. A bovine TB wildlife strategy predicated solely on the vaccination of badgers is not a viable or sustainable policy option.

“Farmers in the IAA and across the whole of Wales are playing their part in bearing down on the disease t h r o u g h s t r i n g e n t cattle control measures, but the reservoir of infection that exists in wildlife has not been confronted. If the Welsh Government is genuine about eradicating Bovine TB in Wales then it has to implement a policy of targeted culling of badgers in areas where the disease is endemic that will actively remove the disease from the badger population in these areas.”

NO NEW EVIDENCE 

A Welsh Government spokesperson told The Herald: “We are fully aware of this interesting work by Professor Rosie Woodroffe, which we have discussed with her in some detail.

“We remain committed to a science-led approach to the eradication of bovine TB. Our current programme includes the testing of cattle, strict biosecurity measures and movement control. This is aimed at tackling all sources of infection. The latest statistics show the number of new TB incidents in the 12 months to April 2016 reduced by 17%.

“We will continue to study all the available evidence relating to the transmission and prevention of bovine TB and are considering how Professor Woodroffe’s observations might feed into continued development of our TB programme. The Cabinet Secretary will make a statement on the Welsh Government’s refreshed TB eradication programme in the autumn.”

FUW Senior Policy Officer Dr Hazel Wright told us: “The latest study by Professor Woodroffe and colleagues provides no new evidence on the issue of bovine TB transmission. The FUW has long recognised that infected badgers can contaminate both pasture and housing via the excretion of M. bovis bacilli in urine, faeces, sputum and exudate from open abscesses.

“Farmers continue to adhere to strict cattle testing, movement and biosecurity measures in an attempt to reduce the level of transmission from badgers to cattle. However, in the absence of any badger control mechanisms, such cattle measures will only have a limited effect on disease eradication whilst having a very significant emotional and financial impact on farm businesses.”