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  • A listeria outbreak has affected multiple people in at least 10 different states.
  • All those affected lived in Flordia or had recently traveled to that state.
  • The CDC reports that the outbreak is linked to a brand of ice cream.

On July 2, the Centers for Disease Control and Prevention (CDC) warned of an outbreak of Listeria. Those affected either lived in Florida or had traveled to the state in the same month they became ill.

“Listeria symptoms usually start within two weeks after eating food contaminated with listeria,” the CDC said.

There have been 23 cases of the disease (listeriosis) identified across 10 states: Colorado, Florida, Georgia, Illinois, Kansas, Massachusetts, Minnesota, New Jersey, New York, and Pennsylvania.

One fatality has been detected in Illinois.

However, the agency emphasized that the true number of cases could be higher than the number reported. This is because some people may recover without medical care and aren’t tested for Listeria.

The CDC said that the infected ranged in age from infant to 92, and cases were reported from January 2021 through June 2022.

A CDC investigation determined the source of infection was Big Olaf Creamery brand ice cream, a brand only sold in Florida.

“Consumers who have Big Olaf Creamery brand ice cream at home should throw away any remaining product. Big Olaf Creamery brand ice cream is only sold in Florida,” the CDC said.

The agency also warned consumers to clean areas, containers and serving utensils that may have touched Big Olaf ice cream products.

John Raimo, MD, chair of medicine at Long Island Jewish Forest Hills in Queens, part of Northwell Health in New York, told Healthline that the disease is caused by a bacteria called Listeria monocytogenes.

“Listeria most commonly causes infection when people eat contaminated food,” he said.

According to Food and Drug Administration (FDA), Listeria monocytogenes may be found in soil, water, moist environments, decaying vegetables, and dead animals.

The agency said Listeria is “generally” transmitted to people through contaminated food, and products can be contaminated with the microbe at any stage of harvesting, processing, or transport.

The FDA warned that this bug can survive and grow under refrigeration and other food preservation measures.

The World Health Organization (WHO) cautioned that foods with a “long shelf-life under refrigeration,” and foods eaten without cooking (which kills the bacteria) are the most likely to be contaminated.

They added that past outbreaks have involved foods that include ready-to-eat meat products, like hotdogs, meat spreads, smoked salmon, dairy products, prepared salads and even fresh vegetables and fruits.

According to Raimo, the severity of listeriosis depends on individual risk factors and whether the infection is contained in the gastrointestinal tract.

“People with infection confined to the gastrointestinal tract typically do well and recover within two days,” he said.

Raimo said symptoms are similar to other types of food poisoning when the infection is limited to the gastrointestinal tract.

“People typically will have fevers, watery diarrhea, nausea, and vomiting,” he said. “They also may have headaches and joint or muscle aches.”

Raimo recommended that people infected with Listeria stay hydrated, adding that they generally don’t require any specific medications.

Severe infection can lead to invasive listeriosis, which occurs when the infection spreads outside of the gastrointestinal system.

“The two major sites of invasive listeriosis are the blood stream and the central nervous system,” said Raimo.

He added that patients with blood stream infections usually have fever, chills and flu-like symptoms.

“They may have a rapid heart rate and low blood pressures,” he said. “Patients with central nervous system infections may have neck stiffness, confusion, loss of balance, tremors, or seizures.”

According to Thomas Kilkenny, DO, Assistant Professor of Medicine at Northwell and Assoc., Director Critical Care Staten Island University Hospital, the incidence of listeria infection associated with pregnancy is approximately 10 times higher than in the general population.

“Most non-pregnant patients with invasive Listeria are either immunocompromised or adults of older age,” he said. “Luckily, the Listeria is susceptible to many different types of available antibiotics.”

He warned that any suspicion that this disease is present is extremely important.

“Because untreated blood and brain infections carry very high mortality rates,” said Kilkeeny. “Fast initiation of antibiotics is important.”

He recommends that if anyone gets ill with gastrointestinal upset and fevers after eating any of the foods associated with infection, they should seek out medical treatment as soon as possible.

According to the WHO, ways to prevent infection include practicing safe food handling practices and following the WHO Five Keys to Safer Food:

1. Keep clean.

2. Separate raw and cooked food.

3. Cook food thoroughly.

4. Keep food at safe temperatures.

5. Use safe water and raw materials.

The WHO also recommends that people in high risk groups should avoid foods that include dairy products made with unpasteurized milk, ready-to-eat meat products and cold-smoked seafood (like smoked salmon).

They also advise reading and carefully following the shelf life period and storage temperatures indicated on product labels.

A CDC investigation into Listeria infections across 10 states has discovered that Big Olaf Creamery brand ice cream in Florida was the likely source of infection.

Experts say those at greatest risk include people who are pregnant, those with weakened immune systems, newborns, and adults over 65 years old.

They also say those at high risk should avoid eating certain foods, like those made with unpasteurized milk or ready-to-eat meat products.