Romaine Lettuce Is Safe to Eat Again: E. Coli Outbreak Source Discovered

The deadly E. coli outbreak that resulted in the deaths of five people and sent hundreds to the hospital is officially over, and now investigators think they might know what caused it.

The initial announcement by the Centers for Disease Control was released April 10 and said that several government agencies—including the CDC and the United States Food and Drug Administration—were looking into a possible E. coli outbreak. Subsequent announcements were made at least once a week for the first month and a half of the outbreak. Announcements were then issued less frequently until the CDC announced that the outbreak was over on June 28.

Those infected were all exposed to the same strain of E. coli that was found to be related to romaine lettuce from the Yuma, Arizona, growing region. Consumers were advised by the Food and Drug Administration to lay off the romaine while the outbreak was happening in May, but there was no formal recall of the lettuce.

It may have been contaminated canal water that caused the E. coli, new information from the CDC shows. Water samples that were taken from the canals near the growing fields in the Yuma region tested positive for E. coli that had a similar genetic makeup to the E. coli that made people sick, said the CDC website.

But the CDC is still trying to figure out how that water may have gotten contaminated in the first place. Testing of the livestock, water, soil and more in the region is underway, according to the CDC.

"More work needs to be done to determine just how and why this strain of E. coli O157:H7 could have gotten into this body of water and how that led to contamination of romaine lettuce from multiple farms," said a statement from the FDA.

Symptoms of E. coli usually appear three to four days after exposure to the bacteria but they can take up to 10 days to present in an infected person. The symptoms can vary, and different people will experience them to different degrees. They can include diarrhea, vomiting and stomach cramps, according to the CDC.

While some people will experience these symptoms in a mild form, the infection can be life-threatening for others. The CDC recommends that anyone who gets a fever above 101 degrees Fahrenheit along with diarrhea should see a doctor. Many cases will go away without medical attention in five to seven days.

romaine pic
In this photo illustration, Romaine lettuce is displayed on May 2 in San Anselmo, California. Justin Sullivan/Getty Images