After four months, the largest E. coli outbreak in more than a decade is finally over. On June 28, the Centers for Disease Control and Prevention announced that there are no new diseases from eating contaminated romaine lettuce that caused the outbreak.
Since mid-March, the CDC and the Food and Drug Administration have identified five deaths and 210 diseases caused by E. coli infections, which are mainly associated with bagged, collapsed Romain.
For months, health officials knew that the contaminated lettuce came from the Yuma, Arizona growing region, where most American lettuce is harvested in the winter. But they could not find the exact source of the pollution, and a number of farms in the area were involved.
Yesterday, the FDA announced that it had made some progress in its case: New samples from the canal water around farms in Yuma were tested positive for E. coli O1
"These first positive samples are another piece of the puzzle," FDA Director Scott Gottlieb said in a statement. "More work needs to be done to find out how and why this strain of E. coli O157: H7 could have entered this water and how this has led to the contamination of romaine lettuce from several farms."
There are many different strains of E. coli, a bacterium, and most of them live in our intestines and cause no harm. But the strain that has now led to the outbreak, E. coli O157, produces toxins that are dangerous to humans, and it is particularly virulent. The bacteria are typically transmitted from animals to humans via animal excrement that has contaminated food or water. The symptoms of infection are cramping, vomiting, diarrhea, and rarely kidney failure and death.
According to a June 28 update on the outbreak, nearly half of the food poisoning patients affected by this outbreak had to be hospitalized, and many developed a severe form of kidney failure. In total, the outbreak hit 36 states, with the five deaths in Arkansas, California, Minnesota and New York. The FDA says the last deliveries of romaine lettuce were harvested by Yuma on April 16, 2018 – so Yuma's greens are no longer sold or served.
But the tragedy should be a reminder of the health threat our comfortable, prepackaged salads can portray.
Identifying the exact cause of this outburst was challenging because we eat salad today
Before turning to the why, we want to make it clear that most of the salad we eat is safe to consume. However, lettuce has also become a major source of food poisoning.
One reason why: The salad we eat today looks very different from the salad our parents or grandparents ate. Instead of buying lettuce heads that we wash and chop or tear apart, sales of cut and packaged greens have increased dramatically over the past few decades. These mixed greens land in our fridges or in the restaurants, which are already washed and ready to be thrown into a salad bowl. During processing, bacteria that live under the leafy vegetables have a moist environment in which to thrive.
"When you snatch and hack [salad] bacteria are simply reinforced – and when shipped across the country, the bacteria have a chance to grow in their pockets," said Bill Marler, one of America's leading food safety lawyers who are affected by this outbreak, Vox said after the outbreak was first declared.
Salads are not the only cause of food poisoning. We also eat them raw, which means that there is no cooking process to kill pathogens. Contamination can happen when lettuce is harvested, or from animals or water in the fields – which can be the case in Yuma.
The packaging process also makes it harder to find the cause of contamination and prevent more people from becoming ill. Different salads grown on different farms are mixed into sacks, which are distributed to supermarkets and restaurants across the country, so that food safety officers must look for the common link between farms and suppliers.
That's Part of the Reason for Food and Drug The administration previously said that we could never know the exact cause of the contamination of E. coli Romans (19659007). In an incredibly complicated chart released earlier this month, the agency revealed that a network of dozens of farms, processors, and traders (all of whom were unnamed) was involved in the current outbreak. Only a few cases of E. coli caused by lettuce have been traced back to a single farm.
We increase the risk of food poisoning from prewashed, bagged lettuce
I asked Marler what the public and health authorities could learn from these deaths, and he said that we need to understand that our love for comfort has also become a risk. When we eat salads that are prewashed and bottled, we increase our risk of food poisoning.
Perhaps the best way to produce Romaine is to ship it all over the head, to leave restaurants and individuals to wash themselves, Marler suggested. Salad eaters may also wonder if the convenience of packaged salad is worth the extra risk.
Scary, almost the same scenario took place in the US a dozen years ago. In 2006, a gigantic E. coli outbreak that was associated with fresh spinach in sacks fell to more than 200 people, killing three in 26 states. It also included conveniently packaged salad.
"Historically, the large E. coli outbreaks associated with leafy vegetables have all [caused by] prewashed, minced and packaged salads," said Marler. "[These] mass produced, washed, packaged, chopped leafy vegetables shipped throughout the country are at a much greater risk than humans realize."