Federal officials have matched E. coli O121 from a sample of General Mills flour recovered from a sick person’s home to the outbreak strain that has sickened at least 38 people since December. The discovery is the smoking gun investigators have been looking for since late April when patient interviews revealed that raw dough made with flour was a common denominator among outbreak victims.

“On June 10, FDA whole genome sequencing on E. coli O121 isolates recovered from an open sample of General Mills flour belonging to one of the consumers who was sickened was found to be closely genetically related the clinical isolates from human illnesses. The flour came from a lot that General Mills has recalled,” according to an update from the Food and Drug Administration this evening. As of 10:45 p.m. EDT, General Mills had not updated the recall and outbreak information on its website. The most recent information from the Centers for Disease Control and Prevention, which has not been updated since June 1, showed that 10 of the 38 confirmed victims had such severe symptoms they had to be admitted to hospitals. Outbreak victims were spread across 20 states as of May 3, which was the most recent illness onset date reported by CDC last week. The first confirmed victim became ill Dec. 21, 2015. “Illnesses that occurred after May 5 might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of two to three weeks,” CDC reported. On May 31, General Mills recalled more than 10 million pounds of flour — sold under the Gold Medal, Gold Medal Wondra and Signature Kitchens brands — from retailers, restaurants and unidentified food producing companies. The varieties of recalled flour include unbleached, all-purpose, and self-rising flours. Best-by dates on the recalled products are as far out as July 2017 on some of the flour packaged for retail sales. “General Mills also sells bulk flour to customers who use it to make other products,” according to the FDA. “General Mills has contacted these customers directly to inform them of the recall. FDA is working with General Mills to ensure that the customers have been notified, and to evaluate the recall for effectiveness. “Because of legal restrictions on commercial confidential information, FDA is not at this time authorized to release the names of these customers or the products they make with the flour.” What should consumers do? Public health officials are concerned that consumers may still have the recalled flour in their homes.

Dr. Karen Neil, a medical epidemiologist with CDC’s Outbreak Response and Prevention Branch, said consumers should check packages they have on hand and throw the flour away if the label codes match those of the recalled products. “Unfortunately flour is one of those things that people usually transfer to their own containers when they get home from the store, Neil told Food Safety News last week. “If that’s the case and you don’t know if your flour is part of the recall, it’s best to follow the food safety rule ‘When in doubt, throw it out.’ “They should also be sure to throughly wash the container and their hands, as well as anything that came into contact with the flour.” Neil said even if consumers plan to use the flour in baking or cooking that would provide a kill step, the flour can very easily cross-contaminate utensils, surfaces and other foods during preparation. She also repeated the CDC’s standing warning about raw dough. “It is very important for people to never eat raw dough or batter,” Neil said, explaining that there is the inherent possibility for raw flour to be contaminated because it is made from wheat, which is grown outdoors, and not subjected to a kill step during production. Anyone who has eaten or handled raw dough or batter and develops symptoms of E. coli infection should immediately see a doctor and be tested. People usually become ill from E. coli O121 two to eight days after swallowing the bacteria, according to the CDC. Most people develop diarrhea, which is often bloody, and abdominal cramps. Most people recover within a week. Some E. coli illnesses last longer and can be more severe, resulting in a type of kidney failure called hemolytic uremic syndrome (HUS). HUS can occur in people of any age, but is most common in young children under 5 years, older adults, and people with weakened immune systems. Symptoms of HUS can include fever, abdominal pain, pale skin tone, fatigue and irritability, small, unexplained bruises or bleeding from the nose and mouth, and decreased urination. (To sign up for a free subscription to Food Safety News, click here.)