Researchers have looked into the main sources and factors behind Bacillus cereus outbreaks over a 10-year period in China.

Scientists said findings can help guide and allocate public resources to prevent Bacillus cereus foodborne cases.

Data from 2010 to 2020 came from the National Foodborne Disease Outbreak Surveillance System.

A total of 419 Bacillus cereus outbreaks were reported, leading to 7,892 cases, 2,786 hospital admissions, and five fatalities. The bulk of outbreaks were recorded in summer, primarily between May and September, found the study published in China CDC Weekly.

link to rice products and schools

The most recurrent food vehicle was connected with rice or flour-based products, notably those made with rice or fried rice and school canteens bore the brunt of outbreaks. This suggests contamination and improper storage during food preparation. So, it is essential to prioritize education for canteen staff on food safety and proper practices, said researchers.

“Given the difficulties students face in discerning food quality and the inherent nature of communal dining in schools, they are at a heightened risk for foodborne disease outbreaks. Therefore, to mitigate the frequency of such outbreaks, supervisory bodies should enhance their oversight and management of food safety in school canteens.”

Bacillus cereus produces toxins that can be classified into vomiting-type and diarrhea-type enterotoxins based on the symptoms they cause. Foodborne infections manifest with symptoms such as nausea, vomiting, and diarrhea.

The most outbreaks occurred in 2018 with 56 while 2012 had the most cases. The peak hospitalization rate was in 2011. One death occurred in 2014 and two each in 2015 and 2016.

Foods derived from rice or flour were identified as the primary cause of most outbreaks and associated cases. Bakery products were responsible for the highest hospitalization rate. Five deaths were traced to rice or flour-based products and complex foods. Rice and rice products accounted for more outbreaks than flour and flour products.

The primary source of these outbreaks, as well as related cases, was school cafeterias. However, the household setting had the highest hospitalization rate and mortality rate.

Factors behind outbreaks

Multifactor contamination was identified as the leading cause for outbreaks and associated cases. This was closely followed by improper storage, accounting for 111 outbreaks and 1,981 cases. The highest rate of hospitalization was attributed to food mishandling and ingestion errors.

In the multifactor classification, the occurrence of two factors was most prevalent. The most frequent combination was inadequate storage and inappropriate processing followed by ingredient contamination or spoilage with improper storage.

To mitigate the risk of Bacillus cereus outbreaks, it is essential to address a multitude of core control and management factors, said researchers.

“These include utilizing safe food ingredients, ensuring cleanliness and standardization throughout the food processing procedure, preventing cross-contamination, thoroughly cooking the food, among others. Implementing proper preservation to inhibit the growth of Bacillus cereus is of great significance.”