HEALTH chiefs say the search for the source of a food poisoning bug which killed three Yorkshire pensioners is continuing after butter containing the bacteria was ruled out as the source of the outbreak.
The three fatalities since October last year have prompted a major investigation by doctors amid a significant rise in cases of listeria poisoning in Yorkshire, with 29 so far detected this year compared to 12 in the whole of 2002.
The Yorkshire Post reported yesterday that the Food Standards Agency had issued an alert about 2kg containers of dairy butter which have been withdrawn by Longley Farm at Holmfirth, near Huddersfield, after traces of listeria were found.
But it yesterday emerged the strain of the bug linked to the butter which had affected 12 people was not the same that had affected the three pensioners, all aged over 80 and from Huddersfield.
Dr Ruth Gelletlie, of the regional Health Protection Agency, said tests had confirmed the three who died with listeriosis had a different strain.
The search was continuing to find any further "common exposures" which could explain other cases.
Hundreds of packs of the butter used in canteens and sandwich bars have already been recalled by Longley Farm and only about 10 are thought to be outstanding.
The company said it had been working with environmental health chiefs in Kirklees and the Food Standards Agency after tests detected the bug in April.
It had immediately stepped up daily inspections and implemented additional safety procedures as a precaution. No traces of listeria had been found in any of its butter for two months, and an inspection by the Health Protection Agency last month gave it the all clear.
It was the first bacterial contamination in the 55-year history of the firm, which employs 130 people in the Holme Valley.
Owner Jim Dickinson said: "We have made every effort from day one to monitor and maintain the highest standards.
"We have also co-operated fully with the relevant agencies and acted on the advice of the environmental health officers. We want to avoid any possibility of a risk to public health."
Any Longley Farm customer with concerns can call the firm on 01484 684124.