More than 200 students were part of a norovirus and Bacillus cereus outbreak at a school in Beijing this past year, according to a recently released study.
Researchers identified 209 cases, of which 28 were laboratory-confirmed, that occurred from late August to mid-September 2018. All ill were students in an age range of 17 to 23 years old. Slightly more than half were male. The outbreak lasted for 13 days, and peaked on Sept. 5, 2018. Cases were widely distributed in all six dormitory buildings and 118 classes.
An investigation indicated canteen employees were infected by norovirus and Bacillus cereus and transmission was possible due to unhygienic practices, according to the study published in the BMC Infectious Diseases journal.
On Sept. 4, 2018, a boarding school in the Shunyi District of Beijing, China reported an outbreak of acute gastroenteritis. The school had 5,043 students. Food from the school canteen was considered as the source of the outbreak. The study documents the first reported outbreak of genotype GI.6 norovirus in the Shunyi District of Beijing, China.
Positive samples from students and staff
Among 35 specimens of rectal swabs or feces from students, 28 were positive. Norovirus GI.6 was detected in 23 specimens, Bacillus cereus in three and both in two specimens. Ten specimens of rectal swabs from 124 canteen employees were positive for norovirus GI, and two were positive for Bacillus cereus. Four of seven food samples were positive for Bacillus cereus but environmental and drinking water samples were negative for viruses or bacteria.
Three norovirus-positive employees reported symptoms of nausea, diarrhea and vomiting between Sept. 1 and 2, but continued to work until Sept. 6.
The main clinical symptoms were nausea, diarrhea, vomiting, abdominal pain, fatigue, dizziness, fever, and headache. No sick people needed hospital treatment.
Students ate only in the school canteen, which had 33 stalls. Each of the stalls operated independently, with different types of food.
Consumption at the drinks stall and rice flour stall on Sept. 1, rice flour stall and fish meal stall on Sept. 2, Muslim meal stall on Sept. 4, and the barbecue stall on Sept. 5 were independently associated with increased risk of disease within the following two days.
An investigation found raw materials and public tableware in the kitchen operation of some stalls were disorderly, and sanitary conditions were poor. Some food was stored at room temperature for a long time.
Information on food manufacture and sale could not be obtained which made it impossible to analyze key control links in the processing and storage of food.
The outbreak was brought under control after implementation of measures such as closure of high-risk stalls, isolation of canteen employees that were norovirus and Bacillus cereus positive, and thorough disinfection of the canteen.
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