Foodborne Disease Outbreak Investigation
On December 22, 2021, CDC reported that they reopened the investigation of a multistate Listeria monocytogenes outbreak that has cases dating back to August 2014. It had previously been investigated in 2019 and 2020 but was closed due to the lack of evidence and inability to identify the source or root-cause. The investigation being reopened was spurred by the outbreak strain being identified from Dole brand garden salad as part of a routine sampling program of food at grocery stores by the Georgia Department of Agriculture in October 2021. With the investigation being reopened, a total of 18 illnesses, 16 hospitalizations, and 3 deaths were reported from 13 states. This outbreak was able to be closed and root-cause identified due to laboratory surveillance for common foodborne pathogens
The CDC investigation is here: https://www(dot)cdc(dot)gov/listeria/outbreaks/packaged-salad-mix-12-21/index.html; the bottom of this page includes buttons for "Investigation Details", "Map", and "Timeline" - please look through all of these.
Additionally, the FDA report is here: https://www(dot)fda(dot)gov/food/outbreaks-foodborne-illness/outbreak-investigation-listeria-monocytogenes-dole-packaged-salad-december-2021.
The assignment is this:
1. Please put on your Epidemiologist hats.
2. Identify the descriptive and analytic epidemiology aspects:
1. Who, What, Where, When
2. Why/How
3. How would you construct an epi triad (i.e. what are the host, agent, and environment of this outbreak)?
4. Consider the two US maps shown on the FDA report (link is above). How would you explain the difference in the number of states from which packaged salads were recalled and the number of states from which cases were reported? Nothing too complex or in-depth - at least 3 sentences, but not more than about 2 paragraphs
5. Include 2 references used (beyond the link above)
Foodborne Disease Outbreak Investigation
Student Name
Institutional Affiliation
Date
Foodborne Disease Outbreak Investigation
Descriptive epidemiology
Who: The outbreak affected individuals aged 65 and older, expected women and people with weakened immune systems.
What: The outbreak was caused by a bacterial called Listeria monocytogenes. The bacteria can be found in moist environments and can survive and grow under refrigeration. When individuals consume food contaminated with the bacteria, they develop a disease called listeriosis, which has adverse consequences including death.
Where: The outbreak was reported in 13 states: Arizona, California, Colorado, Georgia, Illinois, Indiana, Iowa, Kentucky, Maryland, Michigan, Missouri, New Jersey, and Pennsylvania (FDA, 2023).
When: The outbreak started in August 2014 and ended in December 2021.
Epi triad
An epidemiological model assists in understanding the factors which contribute to the spread of disease. The model has three components; the host, the agent, and the environment. The host refers to the population that is vulnerable to the disease. In the case Listeria outbreak, the susceptible population consisted of individuals aged 65 and above, pregnant women and people with weak immunities (CDC, 2022). The agent refers to the disease-causing organism. In the case of the Listeria outbreak, the agent was Listeria monocytogenes. The bacteria can survive in a range of environments, including food. Since the bacteria can grow in very low temperatures, they can easily find their way into refrigerated food (Santos et al., 2019). The environment refers to the physical settings in which a disease is transmitted. In the instance of the Listeria outbreak, the Dole facility in North Carolina. The facility failed to observe sanitation measures, allowing the bacteria to find their way into the salad, which was then distributed to clients.
Di...