A correlation between higher Sika numbers and TB infections in cattle has been found, with Wicklow a particular hotspot.

The conclusion was drawn following analysis of county level data by researchers from Trinity College Dublin and the National Parks and Wildlife Service (NPWS).

Lead author Dr David Kelly from Trinity’s School of Natural Sciences, said that while badger management has made great advances, deer have appeared on the radar as another wildlife host to be managed.

“When attempting to manage TB in wildlife, Sika deer will need to be considered as well as badgers,” Kelly said.

“Our analysis suggest Sika deer are currently of greatest concern in county Wicklow, but if numbers continue to rise in other counties they may also pose problems elsewhere.”

The study, which was supported by the Department of Agriculture, has been published in the journal, Frontiers in Veterinary.

Research method

The number of deer in Ireland has been rising steadily during the 21st century, and studies in Europe and the US have shown that deer, at higher densities, can sustain TB in their herds.

The researchers behind the current study used county-level population densities taken between 2000 and 2018 to track cattle, badgers, and Sika deer – the three known maintenance hosts of TB in Ireland.

The study considered how variations in local densities compared with the variation in bovine TB infection across the country.