23rd May 2012
Up to a third of infected cattle could be missed by the standard test for bovine tuberculosis (bTB) because a liver parasite may be hampering eradication of the disease, research suggests. Dairy cattle carrying both TB and the 3-cm fluke Fasciola hepatica were less likely to reveal the infection, but the fluke has been increasing in the UK [1].
Prof Diana Williams of Liverpool University said the research team had been surprised to find that where there was more fluke there was less evidence of disease. Prof Williams also said fluke had become more common in the UK over the last 15 years – the very period that has seen a threefold increase in the number of cattle herds where bTB was present. She added that flukes could be thriving partly because of climate change and because of on-farm schemes that encouraged farmers to maintain ponds, lakes and marshes to support wildlife.
This carries forward work published in May last year by the Veterinary Sciences Division of the Agri-Food and Biosciences Institute of Northern Ireland [2]. One of their conclusions was that “co-infection with parasites, most notably liver fluke, and also the mycobacterial Johne’s disease, influenced the diagnostic sensitivity of both the comparative skin test and the gamma interferon test”.
David Williams, Chairman of the Badger Trust, said: “The cattle industry should not only welcome these findings but actively follow them up, particularly on behalf of farm businesses that endure persistent bTB breakdowns. For decades badgers have been blamed, now this research clearly shows how infection could stay undetected in a herd. Instead of spending its money on trying to kill badgers the industry should be pressing for all efforts to be made to improve testing and remove the danger of leaving up to one third of a herd still infected.
“Until the science is clear, we should not be making the badger a scapegoat. Remember DDT, myxomatosis and Thalidomide. We thought we knew that these were scientific certainties but they were disastrous. We should be wary for the future”.
NOTES
[1] http://www.nature.com/ncomms/
[2] http://www.dardni.gov.uk/de/
(The Badger Trust has won its application for a judicial review of the legality of the Coalition Government’s decision to kill badgers).