UCD prof links dairy expansion to food-borne bug outbreak

The expanding national dairy herd has been linked to a countrywide outbreak in a food-borne bug that originates in the gut of ruminants, a leading food safety expert has claimed.

This week data published by the Health Protection Surveillance Centre found that there has been a substantial increase in the number of reported cases of illnesses related to the harmful bacteria E.coli O157 – a specific strain of Verotoxigenic Escherichia coli (VTEC).

Since the beginning of the year, a total of 715 cases of illness have been reported – a rise of 197 cases compared to the same period last year.

However, the most marked increase in cases are reported to have taken place in the midlands and the west – regions not generally associated with dairy production.

Alan Reilly – the former chief executive of the Food Safety Authority of Ireland (FSAI) and adjunct professor at the Institute of Food and Health, University College Dublin – claims that there is a direct link between the spike in incidents and extensive slurry spreading around the country.

He also noted the consequences of the severe drought in recent months have also compounded the spread.

The Irish Creamery Milk Suppliers’ Association (ICMSA) has contested some assertions made by the professor, stressing that Irish farmers operate to the “highest standards” of production and farm under “very strict” environmental regulations.

The farm body also highlighted that Irish stocking rates are among the lowest in the European Union.

Recent figures show that in 2010 there were just over one million dairy cows in Ireland; however, by the end of 2017 the average was approximately 1.4 million cows.

Speaking to AgriLand, Prof. Reilly said he believes the extent of the current outbreak is quite telling.

“The breakout at the moment is countrywide and that is one of the peculiar things about it. It’s all age groups – particularly elderly people – which is very different to what we usually see with E.coli O157.

“Principally, it would be children under the age of four; and it would be mainly in rural areas. But this outbreak is quite different to the background levels of cases associated with illness of O157,” he said.

According to the Health Protection Surveillance Centre, VTEC can be found in the intestines of up to 5% of healthy cattle. VTEC bugs can then be shed in the manure of infected animals. It can also be found in healthy sheep.

Some of the ghastly symptoms of the infection include: bloody diarrhoea; vomiting; and abdominal cramps.

Slurry spreading

Prof. Reilly explains that the main source of the bug lives “quite happily” in the gut of ruminants and doesn’t cause any illness in cattle.

“The powerful bacteria enters the environment through the spreading of slurry and can get into humans either by water or direct contact via food.

The more animals we have in Ireland the more slurry we have to get rid of and, at the present moment, the method of disposing of slurry is to spread it on land.

“The greater the numbers of cattle, the greater the quantity of slurry to be spread, and the greater risk it is for recycling these harmful pathogens into the food chain,” he said.

Previous scientific research on the patterns of illness associated with E.coli O157 has found that reported incidents climax during the summer months.

As such, Prof. Reilly points to the impact of the country’s recent heatwave and drought conditions as another contribution factor.

“This peak is associated with the warm temperatures, with the ability of the organism to grow and multiply at warmer temperatures.

“With the drought, and the really dry weather that we have had over the summer months, this is really increasing the potential of the bug to grow and multiply and get into the food chain.

When you are spreading slurry now you are spreading on hard land that can’t absorb it; so it will run off straight away into water courses.

“We know that the cases of illness associated with O157 are related to animal density, private water systems, private wells, septic tanks and the domestic treatment of waste – those issues are key to contamination spreading in the environment,” he warned.

More Sustainable Policies

When asked how confident he is that there is a definitive link between dairy expansion and the current outbreak of the dangerous bug, the UCD lecturer stated:

“It is not rocket science. The more animals you have, the more slurry you have to spread. The more slurry you are putting into the environment the greater the risk of recycling pathogens associated with slurry.

“We know from scientific evidence that with this bug the cases in the community are related to animal density.

As you spread more slurry in the environment, more people are going to get sick – it’s as simple as that.

“This is a really dangerous pathogen; it is really harmful to humans and it can be fatal – we’ve seen elsewhere where people have died from this infection,” he said.

Prof. Reilly is urging Government and all associated state agencies to develop “more sustainable policies” with respect to how animal slurry is disposed of in the future.

“We can’t just go on spreading it on land. We have to treat it; we have to detoxify it before it’s used as fertiliser.

We need joined-up thinking within Government with the concept of a ‘one health approach’ to agricultural policy.

“What happens in the environment impacts on agriculture and food production which then impacts on human health, so we have to link all that up with a concerted policy for sustainable agricultural development and we don’t have that at the present moment.

“The Department of the Environment and the Environmental Protection Agency (EPA) need to sit down with local authorities, the Department of Agriculture, Department of Health, the Food and Safety Authority and the HSE as a group and say ‘we have this problem lads, it’s time to come up with a solution to stop people getting sick and to maintain the growth that we currently have within agriculture’,” concluded Prof. Reilly.

Low stocking rate

In response to the points raised by the former CEO of the Food Safety Authority of Ireland, Pat McCormack, the president of the Irish Creamery Milk Suppliers’ Association (ICMSA), questioned the evidence behind the predication that dairy expansion is playing a decisive role.

However, he did acknowledge that the extremely hot and dry weather conditions in recent months could have been a factor in the outbreak.

The stocking rate per hectare in Ireland is significantly below many other EU member states and Irish animals spend a much higher proportion of their time at grass than in other EU member states – resulting in less slurry spreading.

“Our grass-based dairy system is widely acknowledged as a much more sustainable system of production.

“Quite clearly, the exceptionally warm weather this summer must be a factor and the experience in other member states would suggest that increased animal numbers is not the issue,” McCormack stated.