Liver fluke soars to disrupt bovine TB test results

Press release from the Badger Trust

As MPs prepare to debate badger killing next Thursday (October 25th) two developments show how bovine tuberculosis (bTB) is rooted in cattle.

· At least a fifth of cattle herds and possibly a half may be harbouring bovine tuberculosis (bTB) even after they are thought clear of infection, according to a Cambridge University research article [1]. Worse, there is greater potential for TB to spread within the larger herds which are now becoming more prevalent. These conclusions further justify urgent introduction of cattle as well as badger vaccination.

Badger by Jon Bowen

Badger by Jon Bowen

These conclusions emphasise that the effect of cattle-to-cattle contact is even greater than previously thought and so wildlife culling is even less significant.

· A second problem has been the massive increase in liver fluke which affects the accuracy of the standard test for bTB. This parasite is carried by snails and both thrive in warm, wet summers. Up to a third of cattle with bovine tuberculosis (bTB) could be missed by the standard test for the disease if they are also carrying the parasite, hampering the eradication programme according to research by Prof Diana Williams of Liverpool University [2]. This carried forward work published in May last year by the Veterinary Sciences Division of the Agri-Food and Biosciences Institute of Northern Ireland [3].

The Badger Trust says both these revelations oblige the Coalition to abandon the killing of badgers until the comparatively enormous reservoir of disease in herds is cleared and to introduce compulsory annual testing of all cattle with the more sophisticated techniques now available such as the interferon-γ(IFN) [4]. The killing of a protected wildlife species is even less relevant.

The Cambridge team estimates that there is a high rate of re-introduction particularly in high incidence areas. The authors add that the high rate of external infection, both through cattle movements and environmental sources, must be addressed if recurrence is to be reduced.

The team’s results are in line with the main conclusion of the £50 million Randomised Badger Culling Trial of 1998-2007: while badgers are implicated in bTb, killing them could make no meaningful contributionto its control, and that weaknesses in cattle testing regimes mean that cattle themselves contribute significantly to the persistence and spread of disease in all areas where TB occurs. It added that in some parts of Britain cattle were likely to be the main source of infection and called for the rigid application of cattle-based control measures [5].

 

NOTES

[1] http://www.cam.ac.uk/research/news/scientists-build-a-clearer-picture-of-the-spread-of-bovine-tuberculosis/

[2] http://www.nature.com/ncomms/journal/v3/n5/full/ncomms1840.html

[3] http://www.dardni.gov.uk/de/afbi-literature-review-tb-review-diagnostic-tests-cattle.pdf

[4] Randomised Badger Culling Trial (RBCT): page 14 para 10. http://archive.defra.gov.uk/foodfarm/farmanimal/diseases/atoz/tb/isg/report/final_report.pdf

[5] RBCT report: page 5.

CONTACT The Badger Trust for more information

Jack Reedy

01564 783129

0775 173 1107