Public health and regulatory officials in several states, working with the CDC and the U.S. Food and Drug Administration (FDA), identified ice cream made by Big Olaf Creamery as a potential source of the outbreak. Big Olaf Creamery is voluntarily contacting retailers to ask them not to see its ice cream products until further notice, the CDC said in a July 2 statement. “Consumers who have Big Olaf Creamery brand ice cream at home should throw away any remaining product,” the CDC said. People should also clean and disinfect any surfaces, containers, ice cream scoops, or other serving utensils that may have touched Big Olaf ice cream products, the CDC advised. “Listeria symptoms usually start within two weeks after eating food contaminated with listeria,” the CDC said in a June 30 statement describing the outbreak. Symptoms can start the same day, or up to 70 days later, the CDC said. To pinpoint the source of the outbreak, public health officials interviewed people with listeria infections to determine what foods they ate in the month before they got sick, the CDC said. Out of 17 people interviewed so far, 14 individuals reported eating ice cream. Not everyone recalled specifics about what type of ice cream they had. But among 13 people who did remember details, six said they either ate Big Olaf Creamery ice cream or getting ice cream at places that might have been supplied by Big Olaf Creamery, the CDC said. Big Olaf Creamery, based in in Sarasota, Florida, voluntarily began contacting retail locations to recommend against selling their ice cream products on July 1, the CDC said. The investigation is ongoing.

Who Is Most at Risk?

Certain people are at high risk for listeria infections, including pregnant individuals, newborns, those over 65, and patients with weakened immune systems, the CDC said in June. While other people can get infected, they don’t usually get seriously ill. In the current outbreak, half the patients were at least 72 years old. Five people were pregnant when they got sick, and one person lost the pregnancy, the CDC said. “If you are at higher risk for listeria infection and have symptoms, especially if you recently traveled to Florida, talk to your healthcare provider,” the CDC advised. As of June 29, 2022, a total of 23 people infected with the outbreak strain of Listeria monocytogenes have been reported in 10 states: Colorado, Florida, Georgia, Illinois, Kansas, Massachusetts, Minnesota, New Jersey, New York, and Pennsylvania. Twelve of the people lived in Florida. Among the 10 people with information who didn’t live in Florida, eight people had traveled there in the month before getting sick, the CDC said. “The true number of sick people in an outbreak is likely higher than the number reported, and the outbreak may not be limited to the states with known illnesses,” the CDC said. “In addition, recent illnesses may not yet be reported, as it usually takes three to four weeks to determine if a sick person is part of an outbreak.” RELATED: What Is Listeria Infection? The bacteria L. monocytogenes can cause a serious infection known as listeriosis. While many people have only brief, mild illness when they’re infected, high-risk individuals may develop severe infections in the bloodstream or brain that can be life-threatening. Many people with listeriosis will experience symptoms such as fever, muscle aches, headache, stiff neck, confusion, loss of balance, and convulsions, according to the CDC. Pregnant people may experience some flu-like symptoms, but are also at risk for miscarriage, stillbirth, premature deliveries, or life-threatening infections for their newborns. Listeriosis can be diagnosed with a simple lab test and treated with antibiotics. Foods responsible for listeria outbreaks have shifted over the years, according to the CDC. In the 1990s, most cases were linked to contaminated deli meats and hot dogs. These days, listeria is most often tied to dairy products and produce, with recent outbreaks traced to soft cheeses, celery, sprouts, cantaloupe, and ice cream.