Agency says a total of 63 people in 24 states were infected.
WASHINGTON, D.C., U.S. — The Centers for Disease Control and Prevention on Sept. 29 said it has concluded its investigation of a multistate outbreak of Shiga toxin-producing Escherichia coli (STEC) infections.

Epidemiologic, laboratory, and traceback evidence indicated that flour produced at a General Mills facility in Kansas City, Missouri, U.S., was the likely source of the outbreak, which the CDC said infected 63 people in 24 U.S. states. A total of 17 people were hospitalized, 1 person developed hemolytic uremic syndrome, a type of kidney failure, but no deaths were reported.

“Although the outbreak investigation is over, illnesses are expected to continue for some time,” the CDC said. “The recalled flour and flour products have long shelf lives and may still be in people’s homes. Consumers who don’t know about the recalls could continue to eat the products and get sick.”

The flour recall at General Mills began May 31 and involved Gold Medal Flour and Gold Medal Wondra. Initially affecting 10 million pounds of flour, an expansion of the recall on July 1 increased the affected amount to 30 million pounds and a recall in late July brought the total amount to 45 million pounds. The company also said some of the ill people may have consumed raw dough or batter.

In its Sept. 29 statement, the CDC said public health investigators used the PulseNet system to identify illnesses that may be part of the outbreak. PulseNet, coordinated by the CDC, is the national subtyping network of public health and food regulatory agency laboratories. PulseNet performs DNA fingerprinting on STEC bacteria isolated from ill people by using techniques called pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). CDC PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks.

In interviews, ill people answered questions about the foods they ate and other exposures in the week before they became ill. The CDC found 28 (76%) of 37 people reported that they or someone in their household used flour in the week before they became ill. Nineteen (50%) of 38 people reported eating or tasting raw homemade dough or batter. Twenty-one (57%) of 37 people reported using Gold Medal brand flour. Three ill people, all children, reported eating or playing with raw dough at restaurants, the CDC said.

“This outbreak is a reminder that is it not safe to taste or eat raw dough or batter, whether made from recalled flour or any other flour,” the CDC said. “Flour or other ingredients used to make raw dough or batter can be contaminated with STEC and other germs that can make people sick.”