US authorities have linked a source of the E. coli outbreak to a farm in central California and identified three suspect areas in that state.
However, US health authorities have warned that other farms are likely to be involved in the E. coli outbreak. They ask consumers to check the label before buying romaine lettuce.
The US Food and Drug Administration (FDA) has stated that 59 people in 15 states have been sick from contaminated lettuce.
This is seven more cases than the last review, but regulators are confident that the lettuce responsible for the outbreak is no longer on the market.
However, as the holiday season approaches, the FDA reminds consumers to be cautious and avoid consuming it if they do not know where it comes from.
A water tank
US authorities have said a water tank to Adam Bros. Farms, in Santa Barbara County, has been found positive for the bacterial strain. FDA and US Centers for Disease Control and Prevention officials have not said how the water tank used to irrigate lettuce has been contaminated.
The bacterium can enter water and soil in many ways, including domestic and wild animal waste, fertilizers and other agricultural products.
The investigators linked contaminated lettuce with multiple distributors and processors, suggesting that it must come from several farms.
Three counties targeted
The US government has pinpointed the source of the outbreak to three California counties: Santa Barbara, Monterey and San Benito.
The Roman harvest is now moving to winter growing areas, mainly in Arizona, Florida, Mexico and the California Valley.
Lettuce from outside the three counties of California that was harvested after November 23 should be safely consumed.
28 cases in Canada
The Public Health Agency of Canada reported another case on Thursday. This brings to 28 the number of people who are infected and who are being investigated. Those affected became ill between mid-October and mid-November.
The Agency continues to advise consumers in affected provinces, including Ontario, Quebec and New Brunswick, to avoid eating romaine lettuce and salad mixes containing romaine lettuce unless they are able to verify that lettuce does not come from one of the Californian regions involved.
Benjamin Diaz started working for Debate Report in 2017. Ben grew up in a small town in northern Ontario. He studied chemistry in college, graduated, and married his wife a year later. Benhas been a proud Torontonian for the past 10 years. He covers politics and the economy. Previously he wrote for CTV News and the Huffington Post Canada.