The investigation into the source of the three cases of listeria in Tauranga this week is still ongoing, but there is a likelihood the cause will never be found.
One person died and two others were hospitalised last week which prompted the investigation, and a warning to pregnant women and other at-risk groups.
All three cases were people in their 70s with underlying health conditions.
Twelve cheese and salad products in total have been recalled, after food products from Talbot Forest Cheese's Geraldine-based factory returned a presumptive positive result during routine testing.
But, MPI's Director of Compliance Gary Orr told RNZ reporter Harry Lock there is no link between those products and the confirmed cases.