Evira, in collaboration with Finnish National Institute for Health and Welfare (THL), found that Yersinia pseudotuberculosis bacteria in unpasteurised milk “multiply at refrigeration temperatures to an illness-causing level surprisingly quick."
The bacteria, which can cause acute stomach illness, increased to this level within two or three days "even when the incidence of bacteria in raw milk is originally low," Evira said.
The "illness-causing dose" of Yersinia pseudotuberculosis bacteria was also "found to be smaller than previously estimated," it said.
In addition, "people with no underlying health problems can contract food poisoning with the bacteria levels found in the analysed raw milk," Evira added.
"Only in cooked foods"
Evira and THL joined forces to analyse levels of bacteria ingested by those affected by the “most widespread outbreak caused by raw milk so far in Finland.”
Fifty-five people in the Eastern Uusimaa and Helsinki regions of Finland fell ill between February and April 2014.
Raw milk from a single producer was pinpointed as the source of the outbreak.
On the back of its investigation, Helsinki-based Evira has reiterated its stance on the consumption of raw milk.
"Evira therefore recommends that raw milk be used as soon as possible any only in cooked foods," said Evira.