FDA Investigating Listeria Outbreak With Unknown Source

Health officials are investigating a listeria monocytogenes outbreak that has sickened 11 people, the Food and Drug Administration (FDA) reported Friday. The source of the bacterial contamination remains unknown, and officials have not yet issued any recalls or specific consumer advisories.

Listeria is a significant cause of severe foodborne illness in the United States. Symptoms typically include diarrhea, vomiting, and flu-like symptoms such as fever or chills. In severe cases, the infection can spread to the bloodstream, leading to sepsis, a life-threatening complication. The bacteria can be found in moist environments like soil and water, and can survive in refrigerated conditions. Many foods can harbor Listeria, including unpasteurized milk, soft cheeses, ready-to-eat foods, cured meats, and pre-cut fruits.

While most healthy individuals recover from Listeria infection with mild intestinal illness, the bacteria can cause more serious invasive disease. Symptoms of invasive listeriosis can include fever, muscle aches, headache, stiff neck, confusion, loss of balance, and seizures. These invasive infections require antibiotic treatment and hospitalization. Individuals at greatest risk for severe illness include older adults, pregnant women, newborns, and those with weakened immune systems. Listeria infection can also lead to miscarriages and stillbirths in pregnant women. The CDC estimates that approximately one in five people with listeriosis die from the infection, making it one of the deadliest foodborne illnesses in the U.S.

The FDA is conducting traceback efforts and interviewing patients to determine the potential source of this particular outbreak. According to recent FDA data, there are currently three active Listeria outbreaks under investigation. This new cluster follows a separate outbreak identified on September 23, which has sickened 44 people. Another outbreak, identified on July 22, has also sickened 11 people and still has no identified source.

Officials note that reported cases may only represent a fraction of actual infections, as it is estimated that for every confirmed case in an outbreak, about 29 illnesses go unrecorded. In previous outbreaks, consumers have been advised to thoroughly clean surfaces and containers that may have come into contact with Listeria and to cook food to an internal temperature of at least 149°F (65°C), as the bacteria cannot survive above this temperature.