In a recent Morbidity and Mortality Weekly Report (MMWR), researchers summarized environmental health data collected by the United States (U.S.) state and local health departments during foodborne illness outbreak investigations reported to the Center for Disease Control and Prevention (CDC) via the National Environmental Assessment Reporting System (NEARS) between 2017 and 2019.
Study: Foodborne Illness Outbreaks at Retail Food Establishments — National Environmental Assessment Reporting System, 25 State and Local Health Departments, 2017–2019. Image Credit: BearFotos/Shutterstock.com
Between 2009 and 2015, 25 state, tribal, local, and territorial U.S. public health departments identified 5,760 foodborne illness outbreaks and reported these to the CDC through the National Outbreak Reporting System (NORS).
Though these departments voluntarily provided adequate epidemiologic and laboratory data (e.g., the etiologic agent causing the outbreak, characteristics of retail food establishments, ill worker policy in these establishments, etc.) from their investigations to the CDC, environmental health data from these outbreak investigations were scarce.
Thus, the CDC launched NEARS in 2014 to complement the NORS surveillance and enhance prevention efforts against foodborne illness outbreaks associated with retail food establishments, including restaurants and caterers.
In fact, NEARS is the only source that collects environmental characteristics of retail establishments with foodborne illness outbreaks.
Personnel from public health departments regularly visit retail food establishments for routine inspections and identify violations of their jurisdictions’ food safety laws outlined by the U.S. Food and Drug Administration (FDA) Food Code.
For instance, the Food Code recommends that all food workers wash their hands, use gloves, and not work with food when ill or experiencing specified symptoms. However, the adoption of the Food Code provisions is voluntary and at the will of governments.
Identifying gaps in ill-worker policies of all retail food establishments is crucial for preventing foodborne outbreaks, where contamination of food by ill-food workers is the topmost contributing factor.
About the study
In the present study, researchers described the foodborne illness outbreaks, the establishments where these occurred, the food safety policies of those establishments, and policies identifying and managing ill workers.
Per the CDC definition, a foodborne outbreak is an incident in which more than two individuals experience a similar illness due to consuming the same food.
Likewise, an outbreak agent is classified as confirmed only when a CDC laboratory confirms its presence in each sample, otherwise, they were considered suspected.
For this CDC report, 25 health departments from across the U.S. provided environmental data. It encompassed interviews with food establishment managers where outbreaks occurred and corresponding epidemiological or laboratory data from health departments.
All participating health departments also voluntarily reported their environmental health data to CDC via the NEARS.
The study variables covered characteristics of foodborne outbreaks, characteristics of establishments (e.g., ownership and number of meals served daily), and ill worker policies of the establishments linked to these outbreaks.
FDA and CDC have identified that a foodborne illness agent, its proliferation or increase in toxins released by microbial agents in food and its survival in food despite cooking contribute to an outbreak.
Furthermore, this report assessed whether establishments had ill worker policies in writing and specified the following:
i) mandating workers to report the illness to their manager;
ii) reporting five symptoms of foodborne illnesses, i.e., diarrhea, vomiting, jaundice, sore throat, fever, and lesions;
iii) restricted workers from handling food while ill;
iv) five symptoms in a food worker that made a case for taking leave from work.
The study analyses identified primary contributing factors to outbreaks and gaps in establishment policies related to ill workers.
A total of 25 state and local health departments participating in this study reported 800 outbreaks across 875 retail food establishments to NEARS. Of these 800 outbreaks, 216, 306, and 278 occurred in 2017, 2018, and 2019, respectively.
Around 9% of these 800 outbreaks involved multiple establishments, while the rest occurred in only one establishment, and 3.5% were multistate outbreaks. For 679 outbreaks, an investigator interviewed a retail food establishment manager.
Regarding outbreak characteristics, investigations could identify an etiologic agent in 555 of 800 outbreaks. The topmost etiological agent was norovirus, followed by Salmonella, accounting for 47% and 18.6% of cases, respectively.
Accordingly, outbreak establishments with cleaning and glove use policies had fewer norovirus outbreaks. Among other factors contributing to an outbreak, contamination by a worker suspected of an infectious illness was the topmost; it contributed 20.8% of the top five contamination-related factors contributing to foodborne illness outbreaks.
The study demonstrated that less than 50% of establishments with outbreaks provided paid sick leave to food workers, which might improve food safety outcomes. However, most front-line food workers kept working while ill to avoid loss of pay.
Intriguingly, unsuitable, or slow cooling of hot food was the most common proliferation contributing factor. Thus, bacteria caused nearly 50% of the outbreaks per NEARS data.
Moreover, most establishments where outbreaks occurred engaged in riskier food preparation practices (e.g., reheating, holding), which increased the likelihood of microbial/toxin proliferation or survival.
Most establishments where foodborne illness outbreaks occurred were independently owned (473/725) and served over 300 meals daily. Notably, 624/875 establishments received one critical violation warning during the last inspection before the outbreak.
During interviews with investigators, most managers confirmed their establishment had a written policy mandating all food workers to notify their illness. However, 23% of policies listed all five symptoms workers needed to disclose to their managers.
So, fewer workers notified their managers about symptoms-like sore throat with fever, lesions with pus, and jaundice.
The study data increased knowledge about the environmental context of all foodborne illness outbreaks.
Thus, all health departments could use these report findings to assess food safety priorities to inform their routine and preventive outbreak inspections.
In the future, NEARS analyses should focus on stratifying outbreak data by etiologic agents (e.g., Salmonella) and foods (e.g., poultry and vegetables). NEARS could use regression modeling to assess risk factors associated with specific etiological agents.
Analyses of norovirus outbreaks might help devise policies to reduce outbreaks in retail food establishments.