A wildlife intervention project in Co Down led to a sevenfold decrease in TB rates among badgers, a new study has concluded.
In the Test and Vaccinate or Remove (TVR) project, the TB prevalence rate among badgers was initially 14%, but fell to 1.9% by the fifth and final year of the trial.
The measures involved trapping and testing badgers for TB over a 100km2 area around Banbridge. Badgers that tested positive were culled and TB negative badgers were microchipped, vaccinated and released.
New research, published in the scientific journal PLOS ONE, has found that the measures led to a 39% reduction in TB prevalence among badgers each year.
“These results provide field evidence of a statistically significant reduction in badger TB prevalence, supporting a TVR approach to badger intervention,” the study reads.
The lack of a fully validated TB test for badgers which can be used outside a laboratory under field conditions has been a key concern with the TVR approach to wildlife intervention.
The Co Down project assessed the effectiveness of a new blood test for badgers, known as the Dual-Path Platform (DPP) test. The researchers concluded that the results gave “confidence in the reliability and reproducibility” of the test in the field.
The study found that the DPP test has a sensitivity of around 69%, which means 31% of badgers that are infected with TB will incorrectly test negative. The test has a high specificity of 98%, meaning most of the badgers that do test positive actually have TB.
By comparison, the skin test in cattle has a sensitivity of over 99%, and a specificity of 50-60%.
It means that almost all reactors have TB, but the skin test misses a lot of TB-infected cattle.
Another study which stemmed from the TVR project found that nose-to-nose contact between cattle and badgers was “extremely rare”.
The research, published in the scientific journal Ecology and Evolution, involved a series of cameras being set up across 34 farms in Co Down.
During the 64,464 hours of footage, the researchers found that badgers were never recorded within a farmyard and there was no evidence of cattle and badgers being in the same place at the same time.
The presence of cattle at badger-associated locations, such as setts and latrines, was three times more common than badger presence at cattle-associated locations, for example water troughs.
“Preventing cattle access to badger setts and latrines and restricting badger access to cattle water troughs may potentially reduce interspecific bTB transmission,” the researchers state.