One person has died in the E. coli outbreak linked to romaine lettuce. There are now 121 confirmed cases across 25 states. Investigators continue to look for the source of the implicated romaine, as well as how it became contaminated.

In the past week, public health officials confirmed 23 new cases and added three more states to the outbreak map. A week ago the case count stood at 98 people, making for a 23 percent increase in the number of infected people in seven days, according to the Centers for Disease Control and Prevention.

Of those 102 victims for whom complete information is available, 52 have required hospitalization. California officials have reported one death in their state.

The unusually high hospitalization rate of 51 percent shows the outbreak strain of E. coli O157: H7 is particularly dangerous. Also, 14 of the sick people have developed hemolytic uremic syndrome, a type of kidney failure that can result in kidney transplants, other life-long health problems and sometimes death.

Additional outbreaks are expected to be reported in the coming weeks, according to the CDC. As of the update Wednesday, the illness onset dates for the outbreak victims range from March 13 to April 21.

“Illnesses that occurred after April 11, 2018, might not yet be reported due to the time it takes between when a person becomes ill with E. coli and when the illness is reported. This takes an average of two to three weeks,” the CDC reported Wednesday.

The people confirmed with infections range in age from 1 to 88, with a median age of 29. Sixty-three percent of ill people are female.

Investigators from the Food and Drug Administration have not yet determined where the vast majority of the suspect romaine was grown. Of the outbreak victims, eight are inmates at a prison in Alaska. Officials there report the inmates ate romaine from whole heads. All other victims in the outbreak reported eating pre-chopped romaine at restaurants and from grocery stores,

The source of the whole head romaine was traced back from the prison to Harrison Farms Inc. in Yuma, AZ. Romaine harvest at the farm concluded March 16, according to the FDA.

Efforts to determine the source of the romaine that was chopped are slow going because of shipping and receiving records through the supply chain that more closely resemble a tangled ball of yarn than they do a paper trail.

The only clue they have revealed to the public so far is that the chopped romaine came from the Yuma area because virtually no other growing region was harvesting significant amounts of the leafy green during the time outbreak victims have become ill.

Consequently, both FDA and CDC have repeated the warnings first issued April 13 to consumers, restaurants and retailers and in effect until further notice. The warnings:

“Do not eat or buy romaine lettuce unless you can confirm it is not from the Yuma, Arizona, growing region. Product labels often do not identify growing regions; so, do not eat or buy romaine lettuce if you do not know where it was grown,” the CDC warns.

“This advice includes whole heads and hearts of romaine, chopped romaine, baby romaine, organic romaine and salads and salad mixes containing romaine lettuce. If you do not know if the lettuce in a salad mix is romaine, do not eat it.”

Restaurant operators and retailers should not serve or sell any romaine lettuce from the Yuma growing region. This includes whole heads and hearts of romaine, chopped romaine, baby romaine, organic romaine and salads and salad mixes containing romaine lettuce, the FDA and CDC advised. Restaurants and retailers should ask their suppliers about the source of their romaine lettuce.

People usually get sick two to eight days after swallowing the E.coli germ, according to the CDC. Most infected people develop diarrhea that can be bloody, severe stomach cramps and vomiting, and most recover within a week. Some infections are very mild, but others are severe or even life-threatening.

Hemolytic uremic syndrome can occur in people of any age but is most common in children younger than 5, adults 65 years and older and people with weakened immune systems. Symptoms of HUS develop about a week after symptoms first appear, when diarrhea is improving. Clues that someone is developing HUS include these decreased frequency of urination, feeling very tired and losing pink color in cheeks and inside the lower eyelids.

People with HUS should be hospitalized. Most recover within a few weeks, but some suffer permanent damage or die.

E. coli infection is usually diagnosed by testing a stool sample. Antibiotics are not recommended until diagnostic testing can be performed and E. coli O157 infection is ruled out.