Researchers found that raw flour was the source of an outbreak of Shiga toxin–producing Escherichia coli in 2016, according to a study published in The New England Journal of Medicine.
The multijurisdictional team investigating the outbreak identified 56 outbreak cases. These cases were defined as "infection with an outbreak strain in which illness onset was between December 21, 2015, and September 5, 2016." They compared the outbreak cases with non-STEC enteric illness cases, matched according to age group, sex and state of residence. Additionally, they collected products suspected to be related to the outbreak for STEC testing.
Researchers identified a total of 56 cases in 24 states. They found that infection was significantly associated with the use of one brand of flour and with tasting unbaked homemade dough or batter. They also conducted a trace-back investigation, which helped them pinpoint a common flour-production facility.
"This investigation implicated raw flour as the source of an outbreak of STEC infections. Although it is a low-moisture food, raw flour can be a vehicle for foodborne pathogens," study authors wrote.