Map: TB herd incidence for 2019 ‘highest recorded since 2013’

National herd incidence for bovine TB (bTB) increased slightly year-on-year as of the end of 2019, according to the latest statistics from the Department of Agriculture, Food and the Marine.

As of December 31, 2019, national herd incidence for bTB stood at 3.72%, marginally up on 2018’s figure of 3.51%, and 2017’s 3.47%.

Herd incidence for 2019 was the highest recorded since 2013 and marks the third successive year of increasing bTB levels.

This means that since the beginning of 2019, 3.72% of all herds tested for bTB – some 4,060 herds – have experienced a new breakdown, meaning they have had at least one animal that tested positive for bTB.

As the map shows, bTB levels in many areas overall are low but there are areas with higher levels of bTB in in the north-east of Ireland, including: Monaghan; Cavan; Louth; and north Meath, as well as parts of Clare, Cork, Wicklow and some other districts.

The number of reactors identified through a combination of skin testing and gamma interferon testing (GIF) in 2019 was 17,058, a decrease of 433 from 2018 which was around 2.48%.

GIF testing is able to identify bTB infection at an earlier stage than the skin (SICTT) test which is used for the annual round test.

Therefore, when used appropriately, GIF testing can reduce the chances of leaving residual infection in a herd after de-restriction. We expect by removing more infected cattle earlier the risk of re-infection will fall.

Over the last 10 years herd incidence has fallen from just under 5.09% in 2009 to 3.72%, and reactor numbers have fallen from over 23,805 to 17,058, the department says.

However, continuing efforts are now needed from all stakeholders to reverse the increase in national bTB incidence over the past three years and to reduce levels in 2020, the department said.

Regional breakdown

In a regional breakdown by county, it was found that the herd incidence in Monaghan of 7.02% and Cork North of 6.12% – which is significantly higher than the national herd incidence of 3.72% – are particularly relevant as they have higher cattle densities than other counties and this therefore indicates greater amounts of bTB.

Cork north had the highest number of reactors at 1,993. Monaghan had the second highest at 1,336, followed by Clare with 1,190 reactors.

A targeted, high-impact bTB control plan has been in place in Monaghan and parts of Cavan and Clare during 2019 in collaboration with stakeholders, the department said. Its focus is to identify and eradicate disease in those areas as quickly as possible.

While Wicklow west had the highest herd incidence at 12.33% – 380 reactors – this region has less than 0.5% of the national herd.

Limerick and Longford had the lowest herd incidence at 2.06% and 2.21% respectively, the department concluded.