The number 4 outbreak of 2023 is the leafy greens Listeria outbreak that sickened at least 19 people in 16 states, according to the CDC. This outbreak remains a mystery; the government did not name a brand name, farm, or specific type of product that made those people sick.
The case count by state was: Arkansas (1), California (1), Colorado (1), Illinois (1), Louisiana (1), Michigan (2), Missouri (1), North Carolina (2), Nebraska (1), New York (1), Oklahoma (1), Pennsylvania (1), South Dakota (1), Texas (1), Washington (1), and Wisconsin (2). Samples were collected from July 3, 2018 to March 31, 2023. The patient age range is from less than 1 to 96 years. Eighteen people were hospitalized because they were so sick.
This was a relatively large outbreak for this type of pathogen. Listeria monocytogenes outbreaks are usually small, and most people who contract them and are who are counted in case counts usually get sick enough to be hospitalized.
Of 14 patients who were interviewed, 13 said they ate leafy greens before they got sick. Thirteen percent ate iceberg lettuce, and 10% ate romaine lettuce. Twelve of the patients had packaged bagged salads.
Three of the patients ate leafy greens at long term health care facilities. One person ate leafy greens at a hospital where they were employed. The patients purchased leafy greens and different brands of packaged salads from several different stores.
Symptoms of a Listeria infection can take up to 70 days to appear after a person eats food contaminated with this pathogen; but most people get sick within a few weeks. Early symptoms can include nausea and diarrhea. If the disease progresses to the more severe form, patients will suffer from a high fever, stiff neck, muscle aches, and confusion.