"It could not be determined during this outbreak investigation exactly how Norovirus was introduced into the food establishment. Typically, Norovirus is introduced into a food establishment through a contaminated food product or through an ill individual. The epidemiological investigation confirmed that there were multiple food items associated with illness, and multiple sources of illness. MCDH is also aware of Norovirus infection in the community at the time of the outbreak, through investigation of an unrelated, confirmed outbreak of Norovirus at a local school. Therefore, the likelihood a food item was received at the food establishment already contaminated with Norovirus is low, and this is unlikely to be the source of the outbreak."
https://www.mchenrycountyil.gov/home/showpublisheddocument/109263/638024843979870000
Acute Gastroenteritis (AGE) Outbreak:
D.C. Cobb’s
McHenry, Illinois
September 2022
McHenry County Department of Health
2200 North Seminary Avenue
Woodstock, Illinois 6009
INTRODUCTION
On September 12, 2022, the McHenry County Department of Health (MCDH) was notified of multiple customers who became ill with acute gastroenteritis (AGE) after dining at D.C. Cobb’s located at 1204 N Green St, McHenry, IL (D.C. Cobb’s McHenry). The Division of Environmental Health conducted a full inspection of D.C. Cobb’s McHenry that same day, wherein an Environmental Health Practitioner evaluated and reviewed food handling procedures and practices. After the inspection, the Food Program Supervisor confirmed with the restaurant manager that the restaurant had received calls from two (2) separate parties who experienced gastrointestinal illness after consuming food from D.C. Cobb’s McHenry.
MCDH opened an outbreak investigation into the cluster of illnesses linked to D.C. Cobb’s McHenry on September 13, 2022. The case-control study conducted by MCDH identified one hundred seventy-three (173) ill individuals, one hundred sixty-eight (168) patrons who experienced vomiting and/or diarrhea after eating food from D.C. Cobb’s from August 29, 2022 through September 16, 2022 and five (5) staff who experienced vomiting and/or diarrhea before or after working at D.C. Cobb’s McHenry from August 29, 2022 through September 19, 2022. A case-control study identifies a sample of ill individuals during a specific timeframe and does not necessarily identify all individuals who became ill. The total number of ill individuals identified via this case-control study may therefore underreport the total number of ill individuals associated with this cluster of illness.
This report will review the methodology utilized in this investigation, the final findings, and a discussion of those findings and recommendations to prevent future illness. The appendices include graphs and tables depicting data from the epidemiological and environmental health investigations and laboratory testing, along with various forms used to conduct and organize the data/information received in the field
DISCUSSION
One hundred seventy-three (173) ill individuals, including one hundred sixty-eight (168) patrons and five (5) employees, were identified in the case-control study conducted by MCDH. As mentioned previously, a case-control study only identifies a sample of ill individuals during a specific timeframe and does not necessarily identify all individuals who became ill. The total number of ill individuals identified via this case-control study may therefore underreport the total number of ill individuals associated with this cluster of illness.
The pathogen identified for this outbreak was Norovirus (specifically Norovirus Subtype G1). The incubation period, symptoms experienced by the ill individuals, and the duration of illness were all consistent with Norovirus infection. Clinical specimens from five (5) cases were positive for Norovirus, four (4) of which were positive for Norovirus Subtype G1 (with the last having an unknown subtype).
Norovirus causes an acute infectious nonbacterial gastroenteritis. It is fecal-borne, found in the small intestines of infected persons. It is typically brought into the food chain by people who do not properly wash their hands after using the bathroom. Humans are the only reservoir for these foodborne viruses. Data suggests that people infected with Norovirus may continue to shed virus for a period up to two weeks after symptoms subside.
There are two distinct trends in the epi curve (Appendix E, Figure 1), one from August 29 – September 5, 2022, and one from September 6 – September 13, 2022. Between August 29 – September 5, 2022, a lower number of cases became ill compared to September 6 – September 13, 2022 (the median number of cases who became ill from August 29 – September 5 and September 6 – September 13, 2022 was 3.5 and 18.5 cases, respectively). Less cases may have been identified from August 29 – September 5, 2022 either because less people became ill during this timeframe or because less people who became ill during this timeframe completed the epidemiological questionnaire due to the amount of time elapsed between their illness and the availability of the survey.
In both timeframes, there is no clear bell-like shape that would be indicative of a single point source of illness, such as a contaminated food item or ill employee. Instead of a bell-like shape, the total number of cases who became ill each day in the epi curve is relatively similar within each of the two distinct timeframes, and cases do not start to decrease until September 13, 2022 – the day after Environmental Health staff implemented specific control measures at D.C. Cobb’s McHenry. Therefore, the trends seen in the epi curve are not indicative of a single point source.
The food item analysis identified that people were approximately 2.2, 3.5, or 2.7 times more likely to be ill after eating salad, the southwest chicken wrap, or the fried pickles with Cobb’s southwest sauce, respectively. Three other dishes were found to be associated with illness, although they are not as strongly implicated as a cause of illness: Cobb’s nachos, dynamite shrimp, and vampire tacos with bacon. Additionally, the food item analysis identified that people were approximately 2.4 or 3.3 times more likely to be ill after eating lettuce or green onion, respectively. Taken together, the analyses for dishes and ingredients indicates multiple dishes and ingredients were associated with illness.
With regards to the ingredients identified, lettuce (both romaine and iceberg) is common among many different dishes, including the salads and southwest chicken wrap that were found to be associated with illness in the multiple regression analyses of dishes. The green onion was only eaten in two shrimp dishes, including the dynamite shrimp found to be associated with illness in the multiple regression analysis of dishes performed at α < 0.1. Identifying that these ingredients were associated with increased illness does not necessarily imply that eating these ingredients caused illness. Several dishes identified in the multiple regression analyses of dishes do not contain romaine/iceberg lettuce or green onion, including the fried pickles with Cobb’s southwest sauce, Cobb’s nachos, or vampire tacos with bacon. These dishes commonly have ready-to-eat ingredients added after cooking, allowing for these ingredients to become contaminated with Norovirus by a food handler when they are added to the dish.
It could not be determined during this outbreak investigation exactly how Norovirus was introduced into the food establishment. Typically, Norovirus is introduced into a food establishment through a contaminated food product or through an ill individual. The epidemiological investigation confirmed that there were multiple food items associated with illness, and multiple sources of illness. MCDH is also aware of Norovirus infection in the community at the time of the outbreak, through investigation of an unrelated, confirmed outbreak of Norovirus at a local school. Therefore, the likelihood a food item was received at the food establishment already contaminated with Norovirus is low, and this is unlikely to be the source of the outbreak.
Norovirus is highly infectious and is easily spread person to person and on surfaces that have not been properly cleaned and sanitized. At least five (5) employees were confirmed, through the employee survey, to have worked at the food establishment during their infectious period after being ill with Norovirus symptoms consistent with the case definition for this outbreak. These employees returned to work within twenty-four hours after their symptoms subsided. Food handlers are required to be excluded from work a minimum of 48 hours after being symptomatic and must be educated about good hand hygiene.
There is currently no test available to verify the presence or level of Norovirus contamination on a surface or in a food item. However, regardless of the way that Norovirus was introduced into the food establishment – through inspection, observation, employee surveys, and food product flow evaluations – the Division of Environmental Health identified multiple breakdowns in critical operational procedures that created an environment where Norovirus could remain viable and be readily transferred from food handlers to surfaces, surfaces to food items or patrons, and food handlers to food items – all of which could result in illness spreading to patrons. The most significant of these operational deficiencies are as follows:
1. Failure to provide hot water at a minimum temperature of 100-degree Fahrenheit at the kitchen food service hand sinks.
2. Food preparation taking place where there was no access to a food service hand sink
3. Improper hand washing procedures and washing of hands at sinks that are not designated as food service hand sinks
4. Failure to provide paper towels at one of the food service hand sinks
5. Failure of a food handler to wear food service gloves to cover artificial fingernails
6. Failure to provide a procedure for reporting/correcting a lack of tempered water and/or lack of soap and paper towels at a food service hand sink
7. Approximately 30% of employees indicated that there is no monitoring of handwashing practices by management.
8. Failure of food service employees to recognize that their responsibilities include the handling and/or service of ready-to-eat foods. Ready-to-eat foods require additional hand washing procedures and barriers to prevent transfer of contaminants to food items.
9. Multiple employees indicated that handwashing takes place either in the bathroom or at a sink that is not designated for hand washing purposes only.
10. Failure to provide information regarding handwashing at appropriate stages in the food preparation/food handling processes during the product flow evaluations.
11. While the correct minimum internal cooking temperatures were provided by interviewed staff, no detailed information was provided regarding who/how the internal temperature of the food product is actually verified. Prep staff appears to utilize cooking time as the primary control.
12. Soiled food contact surfaces
13. Chemical dish machine not reaching minimum sanitizer concentration to sanitize dishware.
14. Failure to provide test kits to ensure that sanitizer levels are at effective and safe levels.
Upon intervention by Division of Environmental Health staff to ensure correction of the
above deficiencies, the illnesses associated with the outbreak were immediately and dramatically
reduced until no additional cases of illness were reported.
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