Introducing herd risk categories is “the next logical step” if Ireland is to make progress eradicating TB, a leading researcher in the area has said.

A decision by the Department of Agriculture to send all cattle farmers a TB risk letter containing their herd’s risk category, along with a list of high risk animals, has sparked a backlash.

There are no successful eradication programmes anywhere in the world that do not use herd risk assessment, Simon More, UCD professor at the Centre for Veterinary Epidemiology and Risk Analysis (CVERA), told the Irish Farmers JournaL. Prof More said the programme had to move away from thinking of herds as positive or negative, to a system where there was “a spectrum of risk”.

We cannot guarantee when a herd tests negative that the herd is in fact free

“Fundamentally, what these TB herd risk statements are doing is trying to provide information to assist farmers to better understand where they sit along that spectrum, and also help them to identify those animals that are likely to be at greatest risk,” he explained.

“We cannot guarantee when a herd tests negative that the herd is in fact free. But we can be increasingly sure the longer it is since it last had a breakdown.”

He compared the challenge of TB to COVID-19, where masks and social distancing were used to reduce the risk of spreading the disease, as many people showed no symptoms.

At that point of being free to trade again, we know that these herds pose a greater risk of breaking down again

“One of the key challenges [with TB] is that when your herd is infected, it’s locked up, it has two clear tests and then it’s free to trade. At that point of being free to trade again, we know that these herds pose a greater risk of breaking down again for an extended period of time.”

Farmers were being asked to contribute to the management of their risk in two areas – the risk of residual infection and the risk of introduced animals. Without the statements, farmers did not have the necessary information to do that, Prof More believes.

He added that there were other risks outside of farmers’ direct control, namely badgers and neighbouring lands.

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