BUTTER from a Holmfirth dairy firm has been ruled out as the source of the listeria food poisoning bug which killed three pensioners.
Regional Health Protection Agency experts confirmed today that the Huddersfield victims had a different strain to the one found in catering packs of butter made at Longley Farm.
Environmental health inspectors at Kirklees Council detected listeria in the packs during routine tests in April.
It has been confirmed as the source of 12 cases of the food poisoning bug.
But none involved the three Huddersfield pensioners - all over 80 - who have died in the last nine months.
Dr Ruth Gelletlie, of Yorkshire and Humberside Regional Health Protection Agency, said: "The three patients in Huddersfield who died with listeriosis, had a different strain of listeria and are not linked to this particular food product in any way."
Ten of the farm's suspect 2kg packs of butter, used by cafes and sandwich bars, have still to be traced.
Cases of listeria have risen dramatically in Yorkshire with 29 cases so far this year compared with 12 in the whole of 2002.
Listeria affects people whose immune system is impaired such as the very elderly, pregnant women and people undergoing chemotherapy.