Bovine TB crisis in Ireland: why cattle disease cases are at their highest in 15 years

With herd incidence at a 15-year high, bovine TB remains Irish farming’s most costly, persistent and emotionally draining disease

For Ireland’s massive cattle herd, bovine TB remains a costly and debilitating scourge. File photo

With the number of bovine tuberculosis cases passing 43,000 in Ireland this year and continuing to grow, the issue has emerged as a crisis in agriculture and one that national authorities have been trying to contend with for more than 70 years.

While the disease was a scourge of the human population in Ireland well into the 20th century, becoming one of the leading causes of death, advancements in treatments and containment meant it has been largely wiped out.

However, for Ireland’s massive cattle herd, the bovine version of the disease remains a costly and debilitating scourge.

Bovine TB, commonly referred to as just ‘TB’ in agricultural spheres, is a highly infectious bacterial disease of cattle caused by the bacterium mycobacterium bovis.

A farmer with infected cattle must contend with restrictions and eradications of portions or the entirety of their herd. 

Bovine TB primarily affects the respiratory system and causes lesions in the lungs and other organs. Most cases will be asymptomatic or have no clinical signs, and an infected animal will appear perfectly healthy despite the infection being present.

This is because the disease progresses very slowly, and most animals are slaughtered for beef or detected via a TB test before symptoms develop. TB may also be “latent” or dormant in an animal and may never progress into a clinical case of the disease.

The disease has long been an issue. The Irish Bovine TB eradication scheme was established in 1954. At the time, it was estimated that 80% of the national herd was affected by TB, and 17% of cattle were presumed to be infected.

The eradication programme became compulsory throughout Ireland by 1962. Nationwide TB tests were rolled out, and infected animals were removed and slaughtered from herds.

To put that in perspective, Ireland and its farmers have been battling with TB longer than we have had colour TV broadcasts.

By 1965, Ireland had controlled numbers enough to meet requirements to trade within the European Economic Community, which we entered successfully in 1973.

In more recent times, the country experienced a historic low for TB herd incidence at 3.27% in 2016. However, this milestone in 2016 has been dramatically reversed with herd incidence spiking in recent years.

In response to rising TB figures in 2018, the TB Stakeholder Forum was established to reduce TB prevalence in the national herd, with the ultimate goal of TB eradication.

In May of the same year, then-agriculture minister Michael Creed secured government approval for an ambitious plan: To eradicate Bovine TB by 2030. Yet, this commitment has since been retracted, leaving the future of the disease’s eradication in doubt.

Conor O’Mahony, a representative of the Department of Agriculture, stated in a recent Oireachtas committee meeting: “I don’t think we [the Department of Agriculture] can confidently say we are going to eradicate TB by 2030 given where our current disease levels are.”

It was revealed earlier this year that in 2024, herd incidence reached 6.04%, the highest TB herd incidence to be recorded in the last 15 years.

TB costs

Aside from the welfare of both animal and farmer, and the emotional burden, TB costs Ireland greatly in the continuous battle to control outbreaks. It is set to cost Ireland approximately €130m this year alone, based on current disease rates. 

If these figures are to continue, TB is forecast to cost the country €170m in 2026. In a report published by the Irish Farm Accounts Co-operative (IFAC) earlier this year, TB eradication has cost Irish farmers €151.5m in 2024.

The largest cost to farmers is the cost of labour to facilitate a TB test. File photo

The largest cost to farmers, according to the report, was the cost of labour to facilitate a test. Depending on herd size and the number of animals tested, a test could be a couple of hours or a whole day, all of which labour must be paid for. 

IFAC concluded that the injection day and subsequent reading of a test amounted to €55.54m for 2024.

The second largest expense was the direct cost of the TB test, amounting to €36m. Currently, a farmer must pay for one TB test per year themselves and any subsequent or extra testing will be covered by the Department of Agriculture.

“Private” tests on animals such as calves, which farmers may have wished to sell but were not present for the last herd test, were not included in the calculation.

Herd reactors

If a herd has a reactor in the TB test, the Department of Agriculture is notified. The herd where the TB breakdown has occurred and potentially linked herds, such as neighbouring farms, will be restricted from selling or moving any cattle to prevent disease spread.

Milk restrictions may also be applied if the herd provides supplies for raw milk and raw milk products, as heat treatments must then be applied.

Farmers are compensated for reactors. A valuer will come to the farm and apply a score and value to the animal based on prices set by the Department of Agriculture.

There is a ceiling applied to compensation of €3,000 for an individual animal — unless the reactor is a stock bull, where the ceiling is €4,000, or a pedigree stock bull, where a price ceiling of €5,000 applies.

Once reactors are removed from the farm, the herd will undergo another TB test no sooner than 60 days after the removal date of the last reactor. After another period of 60 days, a second TB test is performed. 

If both tests reveal no reactors among a herd and thorough disinfection of the premises has been completed, a herd can be ‘de-restricted’.

TB resilience

Despite Irish agriculture’s ability to rid itself of many diseases, such as Foot and Mouth, there are many factors with regard to TB and why we aren’t seeing results in its eradication.

Some popular reasons are disease dormancy, the complex interactions between cattle and wildlife, cattle movements in the country, and the lack of an adequate vaccine.

TB can lie dormant in an infected animal and fly below the radar for a number of years. The bacteria can potentially lie dormant in the infected animal for an entire lifetime without reactivation or symptoms. 

Current vaccines on the market would skew the tests Ireland currently relies on to identify infected animals. File photo

A dormant infection can be reactivated during periods of stress or in older animals. This makes control difficult and pinpointing infected animals harder if the disease is dormant within the animal.

As of July 30, New Zealand has 15 herds in the entire country with a current TB-infected status. Irish agriculture, particularly dairy, likens our practices to our Kiwi counterparts — yet they have a better position in their eradication journey, even with a wildlife vector and reservoir of TB in their wild possum populations.

This contrast is chalked up to animal movements within the countries. The New Zealand trend is to have large farm holdings and herds compared to Ireland’s traditional smaller family farms. Because of this, Irish cattle move much more between farms and locations.

Notably, Kiwi farmers tend to sell cattle directly to processing plants for an animal to be culled and processed, whereas in Ireland, it wouldn’t be uncommon for cattle to be sold at a livestock mart to then be sold on later to factories.

Last year, more than 1.88 million cattle were sold through Irish marts.

There is also no suitable vaccine for the disease. Current vaccines on the market would skew the tests Ireland currently relies on to identify infected animals. The tests we conduct cannot distinguish between an infected and vaccinated animal, providing positive results when testing vaccinated animals.

Wildlife sources of TB

You also can’t go long talking about Bovine TB without also discussing the badger. Badgers have a significant impact on TB in cattle as they can act as both a source and a reservoir for the disease.

Badgers were first recognised as a vector of the disease in the 1980s by the Department of Agriculture. Badgers can infect cattle through cross-species transmission, either through direct or indirect contact.

Transfer occurs when wild animals have access to contaminated water points, food, or contaminated fields with excrement.

With Ireland’s predominant outdoor grazing for cattle, the risk of contamination from wild animals is relatively high and largely unavoidable unless populations are controlled or setts are fenced off.

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There is a national vaccination programme with 14,000 badgers captured between 2023-2024. Just over 7,000 of these badgers were culled due to TB.

Deer are also a vector of the disease; however, research is not as widespread. It is found that in some areas with high densities of deer, cattle, and badger populations, the disease can jump between the species. 

The department have stated, as of current research, that there is currently no evidence that deer play a significant role in the spread of the disease and are therefore not within the TB eradication programme.

New measures

Currently, the Department of Agriculture are debating and proposing new eradication measures to try and curb the national crisis.

A proposal of particular contention is the publication of historic TB data of herds when an animal is being sold in a mart.

This could mean on the information board broadcasting in a cattle mart or online via a livestream feed of a mart — alongside the animal data such as date of birth, animal ID number, last TB test — could be a full history report of TB-positive incidences within a herd, despite being currently TB-free, will be broadcast to potential buyers.

Zoe Geary: 'Sadly, TB is not a one-and-done infection where immunity is granted after a little hardship.' Picture: Eddie O'Hare

This is proposed to protect buyers in a market so they can make informed purchasing decisions, but others argue it further isolates farmers who have experienced TB — reaffirming the pariah status of farmers who have had or have TB within their herds, unable to move past their hardships, long after overcoming and recovering from them.

There is still a long way to go when it comes to the fight against TB, with more research, fresh ideas, and funding needed to try and curb our current numbers and begin reversing incidences.

Sadly, TB is not a one-and-done infection where immunity is granted after a little hardship. The mental and emotional scars as a result of an infection within a farm are shouldered by the herd, farmer, and farming family for years after the fact. Any farmer would agree that they wouldn’t wish it on their worst enemy.