A Norovirus Foodborne Outbreak at a restaurant in Pingtung County, Taiwan, February 2024

Leng Lin^1*, Angela Song-En Huang¹, Yung-Ching Lin¹, Hao-Hsin Wu²

2026 Vol.42 No.2

Correspondence Author： Leng Lin^1*

Abstract：

Background:
In February 2024, an outbreak of gastroenteritis affected at least 272 persons who dined at a self-serve grilled oyster restaurant in Taiwan. We investigated to determine the causative agent, mode of transmission, and source of illness.
Methods:
We conducted a case-control study using a structured questionnaire for a convenience sample of customers who dined at the restaurant from February 11–15, 2024. Data on gender, symptoms, and food exposure were collected. A confirmed case had diarrhea or vomiting within 72 hours plus at least one of: abdominal pain, fever, or nausea. On-site investigations, staff interviews, and stool/environmental sampling were performed. Associations between food items, oyster grilling behaviors, and illness were analyzed using Chi-square or Fisher’s exact test.
Results:
Of the 72 (26%) individuals sampled from 272 affected persons, 60 (83%) responded to the questionnaire, and 50 met the confirmed case definition. The analysis revealed that only the consumption of grilled oysters was significantly associated with illness (p < 0.001). The restaurant was an open, well-ventilated space. No employees reported gastrointestinal symptoms within five days prior to the outbreak. Restaurant employees could not be sure that customers ate thoroughly grilled oysters, as there were no clearly posted signs providing oyster grilling instructions. Among the 11 stool specimens tested, norovirus of genotype GII.17 was identified in all eight specimens from confirmed cases, but not in the three specimens from staff. Environmental samples, including water, knives, and cutting boards, tested negative for pathogens.
Conclusion:
This outbreak of norovirus-related gastroenteritis was linked to the consumption of inadequately grilled oysters, likely due to a lack of clear cooking instructions for customers. We recommend that restaurants serve thoroughly cooked shellfish and educate the public on the risks of undercooked food to prevent future outbreaks.

Keywords：Foodborne Diseases, Gastroenteritis, Norovirus, Oyster