What's the Most Common Cause of Foodborne Illness Outbreaks at Restaurants? The Answer Might Surprise You

  • Sick restaurant workers cause a significant portion of foodborne illness outbreaks, according to new data from the CDC.
  • The most common cause of illness was norovirus, accounting for more than 47% of outbreaks with an identifiable agent.
  • Experts say more comprehensive policies for ill and infectious employees—including paid sick leave—may help reduce outbreaks.

restaurant worker adding vegetables to bowl

restaurant worker adding vegetables to bowl

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Sick restaurant workers cause a significant portion of foodborne illness outbreaks, according to new data released by the Centers for Disease Control and Prevention. Experts say a contributing factor to the outbreaks is a lack of comprehensive policies—including paid sick leave—for ill and infectious employees.

The data comes from a study published in Morbidity and Mortality Weekly Report (MMWR), dated June 2, which looked at foodborne illness outbreaks reported to the National Environmental Assessment Reporting System (NEARS), between 2017 and 2019, by 25 participating state and local governments.

During that two-year period, a total of 800 outbreaks associated with 875 retail food establishments were reported to NEARS. Among those 800 outbreaks, investigators were able to identify at least one contributing factor in 500 of the reported outbreaks—of those 500, 41% (205) were associated with sick workers.

The most common cause of illness was norovirus, accounting for 47% of outbreaks with an identifiable agent; Salmonella was the next most common, accounting for nearly 19% of outbreaks.

According to study authors, retail food establishments should adopt more comprehensive food safety policies in order to help prevent foodborne illness outbreaks. “Ill workers continue to play a substantial role in retail food establishment outbreaks,” the authors of the report wrote, “and comprehensive ill worker policies will likely be necessary to mitigate this public health problem.”

What Are the Symptoms of Norovirus?

Most common:

  • Nausea
  • Vomiting
  • Diarrhea
  • Abdominal pain

Less common:

  • Fever
  • Headache
  • Body aches

A Lack of Comprehensive Food Safety Policies

In addition to looking at foodborne illness outbreaks and their causes, the investigators of the report also interviewed 725 managers at some of the outbreak sites.

“In most of the outbreaks included in this report, the restaurant lacked policies that required workers with certain symptoms to notify their manager and stay home or not work with food,” lead study author Erin Moritz, PhD, an epidemiologist at the Centers for Disease Control and Prevention, told Health.

Most of the managers confirmed that their establishments had policies requiring food workers to tell their manager when they were sick (92%), and restricting ill workers from working (86%). Almost two-thirds of these managers said those policies were explicitly written down.

But when it came to specific symptoms that either required reporting or excluded workers from working, less than one-fifth of managers said their policies listed all five symptoms recommended by the Food and Drug Administration’s Food Code: vomiting, diarrhea, jaundice, sore throat with fever, and/or an open or draining lesion containing pus.

The study authors noted that written policies are more effective in preventing illness than policies that are verbally communicated, but those requirements alone are “unlikely to markedly reduce incidence of foodborne illness outbreaks in retail establishments”—managers have to actually implement the policies and workers have to actually comply with them to be effective.

What Is a Stomach Virus?

Paid Sick Leave May Help Reduce Outbreaks

Experts say compliance is more complicated than just giving people a list of symptoms to report and telling them stay home when they’re sick. It’s important to note that many food handlers are paid hourly, and calling out of work means taking a pay cut; and managers often have to find a replacement quickly for sick worker.

“One thing that the CDC does not touch on is sick leave policy,” Donald Schaffner, PhD, a quantitative microbial risk assessment expert and professor at Rutgers University, told Health. “If someone is working a job and they don’t get paid if they call in sick, that represents a strong incentive to work while sick.”

Because of this, it’s also likely that sick employees—and foodborne illnesses caused by them—are much more common than the new research might suggest. “We are only looking at reported and validated data,” Darin Detwiler, LPD, an associate professor of food safety at Northeastern University, told Health. “Many times, not only do employees and consumers not report their illnesses, but the CDC estimates that, for every case of foodborne illness reported, a large number go unreported.”

Ultimately, study authors said restaurants and other food establishments should consider implementing comprehensive policies for sick workers with a focus on compliance. “To help alleviate these issues, the food service industry can foster a work environment that encourages workers to stay home when sick, by considering measures such as paid sick leave and good staffing plans,” Moritz said.

Schaffner added that “ensuring workers [earn] a living wage with appropriate paid sick leave policy will go a long way to addressing this problem.”

These policies—including potential paid sick leave—should also not be viewed as an employee perk, but as an integral part of business. “This should not be viewed as a benefit,” Detwiler said, “but as a requirement for the benefit of employees, of the company and their reputation, and of consumers.”

Stomach Flu vs. Food Poisoning: How To Tell the Difference

Protecting Against an Invisible Threat

Although the symptoms of norovirus and other foodborne illnesses are far from subtle, viruses and bacteria can end up on your food without your knowledge in a restaurant setting. “We are talking about invisible dangers and about information regarding employees that consumers are unlikely to know,” Detwiler said.

The only way to fully protect yourself from restaurant foodborne illness is to avoid eating anything other than food prepared in your own home—but that’s unrealistic for many people. You can, however, consider a restaurant’s reputation before choosing to dine there.

“If consumers are aware of companies that have repeated violations or that are tied to outbreaks, perhaps they can be avoided,” Detwiler said.

Additionally, Moritz suggests checking inspection scores of the restaurants you commonly visit, which can be found on your local health department’s website.

And while it should go without saying, if you see someone vomit in a restaurant—whether it’s a customer or staffer—Schaffner recommends you leave immediately. “Unlike many other foodborne diseases,” Schaffner said, “We know that norovirus can also spread through vomit as well as diarrhea.”