As of Monday, the FDA said the outbreak has resulted in 43 people becoming ill in 12 states, with the last reported illness onset date on October 31.
This most recent confirmed case is in an adult under the age of 65.
"Preliminary traceback information indicates that ill people in several areas across the country were exposed to romaine lettuce harvested in California".
There have been no new confirmed cases since Friday. For romaine that doesn't come in packaging, grocers and retailers are being asked to post the information, including by the register. "Our investigation at this point suggests that romaine lettuce associated with the outbreak comes from areas of California that grow romaine lettuce over the summer months, and that the outbreak appears to be related to "end of season" romaine lettuce harvested from these areas".
Investigators have been tracing back the romaine eaten by people sickened in the outbreak. "One outcome could be to extend the commitment for labeling for origin and date of harvest to other leafy greens".
Robert Whitaker, chief science officer of the Produce Marketing Association, said labeling for romaine could help limit the scope of future alerts and rebuild public trust after other outbreaks.
After posting the advisory Tuesday, the FDA investigated the outbreak over the Thanksgiving holiday period.
A limited recall of romaine in May 2018 led to $70 million less in sales from April to June than in the same period the previous year, according to an industry report.
Under the Trump administration's FDA regulations, produce growers won't be required to begin annual testing until 2022, after which any grower with an E. coli problem will have an additional two years through 2024 to resolve the issue. USA investigators never specified which salad green might be to blame for those illnesses, which happened around the same time of year as the current outbreak.
"To have something repeat in this way, there simply must be some environmental source that persisted", she said. Steps include expanding buffer zones between cattle lots and produce fields. Another possibility, she said, is that winds blew dust from the cattle lot onto produce.
"Based on further discussions with the leafy greens industry and with agricultural authorities, we have begun to narrow the location in which we believe the contaminated romaine in the current outbreak was grown", Gottlieb said. The FDA's Gottlieb has said the leading suspect is contaminated canal water used by multiple farms.
"Those who are experiencing food poisoning symptoms after consuming Romaine lettuce are advised to seek immediate medical attention at the nearest clinic or hospital."The outbreak linked to romaine earlier this year cast doubt on how effective the measures have been, he said.