A new study led by scientists at the Agri Food and Biosciences Institute (AFBI) has found that bovine TB rates among deer in NI stand at around 2.5%.

As part of the research, 522 deer were culled across NI over a five-year period and bovine TB was subsequently confirmed in 13 animals.

“Deer appear to play a comparatively small role in the epidemiology of bovine TB in NI,” the researchers state.

The study, which has been published in the scientific journal Infection, Genetics and Evolution, found cattle can spread TB infections to deer “in a small number of cases”.

Relatively rare

“Infected deer can also spill infection back to cattle, but again these events seem relatively rare,” the research paper reads.

Badgers represent a far bigger source of TB within NI wildlife, with the most recent DAERA figures showing that 21.3% of roadkill badgers tested positive for the disease in 2023.

However, the authors of the new study warn that “circumstances can change over time” and TB infections within deer populations in NI should still be closely monitored.

The example is given of Wicklow, where the deer population has increased considerably, and the animals are now seen as “a maintenance/reservoir host” of TB in the county.

Previous studies have found that TB incidence among deer in Wicklow is around 16%, whereas disease rates in deer across the rest of the Republic of Ireland are only around 4%.

“It would therefore be beneficial to have robust, systematic data on deer species’ population size, distribution and density alongside TB status,” the authors of the NI study recommend.