A Thanksgiving Day Norovirus Outbreak at a Tennessee Restaurant, 2017

What happened

On November 28, 2017, the manager of a Tennessee restaurant reported 18 complaints of stomach illness from people who had eaten there on Thanksgiving Day, November 23. The Tennessee Department of Health investigated.

• That day the restaurant served 676 people a limited menu from 11 a.m. to 8 p.m.
• Around noon, a diner vomited in a private dining room. An employee cleaned it at once with a disinfectant spray labeled as effective against norovirus — then, after washing hands, served family-style platters and cut pecan pie.

The investigation

Investigators phoned every patron with contact details (114 had reservations) and enrolled 137 (20%) in a case-control study: thirty-six cases (two confirmed, 34 probable) and 101 controls. A probable case had diarrhea (three or more loose stools in 24 hours) or vomiting within 72 hours of the meal; confirmed cases also had norovirus found in stool.

• Illness began November 23–25, with 17 of 35 cases (49%) on November 24. The average incubation was 31 hours, and illness lasted on average 3 days; only one person sought medical care.
• Symptoms: diarrhea (94%), fatigue (83%), nausea and cramps (80%), vomiting (69%) and fever (17%).

Cases by date of illness onset. Figure from the CDC report.

What spread it

• Timing mattered most: people seated between 11 a.m. and 1 p.m. — around the vomiting — had six times the odds of falling ill (odds ratio 6.0), and that stayed significant when all factors were weighed together.
• Pecan pie was the only food linked to illness (odds ratio 2.6), though only 16 of 34 sick patrons (47%) had eaten it — pointing to inadequate handwashing by the employee who served it.
• Where people sat — the private room or the main dining area — made no significant difference.
• The lab: two patients had norovirus GII.P16-GII.4 Sydney, and norovirus GII was found on the underside of a table leg next to where the diner vomited.

Conclusion: a single vomiting episode set off a point-source outbreak. Near the vomit, the virus likely spread through the air or on surfaces; across the restaurant it could have spread by air, person to person, via surfaces or food.

Prevention

• In hospitals, CDC and the Tennessee Department of Health recommend gloves and gowns when staff handle vomit; the Food and Drug Administration's 2017 Food Code says restaurants should have a written plan for when and how employees use protective equipment to clean it up.
• Proper handwashing and thorough cleaning, with the right protective equipment, can prevent or limit outbreaks like this one.

Sources

Based on Julia Brennan, Steffany J. Cavallo, Katie Garman and others (CDC, the Tennessee Department of Health and Vanderbilt University Medical Center), "Notes from the Field: Multiple Modes of Transmission During a Thanksgiving Day Norovirus Outbreak — Tennessee, 2017," MMWR, Centers for Disease Control and Prevention; a work of the United States government in the public domain.