Possible import route identified for Northern Ireland’s LA-MRSA case

The recent case of the weaner in Northern Ireland that tested positive for livestock-associated methicillin resistant Staphylococcus aureus (LA-MRSA) could be linked to imported stock after all, writes Graeme Kirk.

Late last week Nothern Ireland’s Department of Agriculture and Rural Development (DARD) told Pig World that there had been no imports of stock onto the unit, but it updated its statement today (August 4) to say there had been no imports in the past two years.

Pig World was also contacted independently by someone close to the case who confirmed that a small number of gilts had been imported into the herd two years ago. They were of the opinion that it was highly likely that these were the source of the LA-MRSA bacteria.

LA-MRSA was identified in a single weaner out of a batch sent for post mortem by a Northern Ireland pig producer. This revealed that the animal had died of pneumonia, but the tests also found LA-MRSA to be present in its liver, lungs and spleen. There were no clinical signs of the disease in the weaner or the herd.

Until now, the UK herd was thought to be free of LA-MRSA in its pig herd. A study that looked at dust samples from pig units back in 2007 found no sign of the bacteria.

LA-MRSA is a problem among pigs in the United States, The Netherlands, Germany and Denmark, among others. In The Netherlands, anyone associated with a pig unit is tested for LA-MRSA prior to elective surgery, and if positive will be refused treatment until they’re clear. Emergency cases involving people positive for LA-MRSA are treated in isolation units to prevent the bacteria getting a foothold in the hospital.

LA-MRSA is not notifiable and is not a public health issue as long as usual meat handling protocols are followed. Even is someone picks up the bacteria, they can carry and shed it with no ill effects unless their immune system is compromised. 

DARD told Pig World that the case posed no risk to the general public and was different from the MRSA strain that can be found in healthcare.

“LA-MRSA presents a low occupational risk for those working in close contact with infected livestock and is not a notifiable disease,” a spokesman added. “Meat from LA-MRSA affected animals is perfectly safe to eat provided normal good hygiene and thorough cooking practices are observed.”

Pig World understands that swabs have been taken from buildings on the affected unit to carry out tests for the presence of LA-MRSA, but no other action is being taken and the farm is continuing to operate as normal. LA-MRSA is an accepted fact of pig production in much of Continental Europe. It has also been identified in the UK dairy herd and can be carried in milk.

The Norwegian government recently culled a pig herd that tested positive for LA-MRSA. While said to be a move designed to help eradicate the problem, this high-profile step was also used to highlight the problem in Danish pigs in what’s generally considered to be a heavily protected pig market. 

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