Preventing Foodborne Illness: Bacillus cereus

This is one in a series of fact sheets discussing common foodborne pathogens of interest to food handlers, processors, and retailers.

What is Bacillus cereus?

Bacillus cereus is a Gram-positive, facultative anaerobic bacterium characterized by large rod-shaped cells and the ability to form heat-resistant endospores. Since this bacterium is widely distributed in the environment and often found in soil, it is naturally present in a wide range of food products from both plant and animal origins. B. cereus can grow in a temperature range of 39 to 118°F (4 to 48°C). Optimal growth occurs within the narrower temperature range of 82 to 95°F (28 to 35°C) and a pH range of 4.9 to 9.3 (FDA 2012).

While there are numerous known species in the genus Bacillus, only two, B. anthracis and B. cereus, are associated with human diseases. Bacillus anthracis, though pathogenic, is rarely linked to foodborne illness. However, Bacillus cereus is a known source of two distinct types of foodborne illness. Both illnesses are associated with the ingestion of a distinct toxin produced by the bacteria. The first is the emetic form, which is characterized by nausea, vomiting, and abdominal cramps. The emetic form has a short onset time of about one to six hours after consumption of contaminated foods and is caused by the ingestion of a pre-formed toxin. The temperature range for emetic toxin (cereulide) production is 77–86°F (25–30°C) (FDA 2022b). The second, the diarrheal form, causes diarrhea, has a longer onset time of about 6 to 15 hours, and can last approximately 24 hours. This illness is caused by enterotoxins (toxins that specifically affect the intestinal mucosa) produced by B. cereus in the intestine following ingestion (FSANZ 2013; Naranjo et al. 2011).

Transmission of Foodborne Illness

Due to its ubiquity in the environment, B. cereus can easily contaminate a wide range of fresh and processed food products. It is found in the environment and on many foods, including meat, cereal dishes, vegetables, milk products, puddings, and soups, but it does not usually pose a health risk. Illness typically occurs when food is improperly cooked and stored in the danger zone (41 to 135°F) (FDA 2022b) for extended periods (Marriot and Gravani 2006).

Transmission of the diarrheal form of the illness occurs through ingestion of viable cells or spores. These cells grow in the body and secrete toxins (whereas the emetic form involves ingestion of a preformed toxin present in the food) (Bottone 2010). The diarrheal form typically requires a concentration of 100,000 or more cells/g to cause illness (FDA 2012). In most instances, illnesses associated with B. cereus result from improper food handling, storage, and cooling that allow the growth of B. cereus and/or the production of emetic toxins.

Cooking contaminated food at recommended temperatures destroys the vegetative cells of B. cereus. Heat-resistant endospores from this organism are more likely to survive cooking and germinate and grow when the food is cooled gradually over an extended period. The emetic toxin is heat-stable up to 250°F (121°C) (Rajkovic 2014). If stored at improper temperatures for several hours before serving, > 41°F (5°C) for cold food; < 135°F (57°C) for hot food, hazardous concentrations of bacterial cells or toxins may develop prior to consumption (HPSC 2012). The temperature range between 135°F (57°C) and 41°F (5°C) is known as the danger zone for food storage and should be avoided (FDA 2022b).

Additional sources of foodborne illness outbreaks include improper hygiene during food canning and inadequate reheating of food in congregate settings, such as restaurants and schools (HPSC 2012).

What foods have been commonly associated with Bacillus cereus?

A broad range of foods have been identified as vehicles for B. cereus. These include boiled or fried rice, cooked vegetables and meats, pasta, vanilla sauce, custards, casseroles, pastries, salads, soups, ice cream, and herbs and spices (FDA 2012). The emetic form of illness (vomiting) is most frequently associated with improperly refrigerated starch dishes, such as fried rice, whereas the diarrheal form is more commonly associated with foods containing meat and vegetables (Todar 2012).

There are many examples of outbreaks caused by this organism. In 2014 in China, 139 people reported nausea, vomiting, and diarrhea after consuming fermented black beans. Three strains of B. cereus were isolated from the outbreak, including two emetic-toxin–producing strains and one strain producing the diarrheal enterotoxin (Zhou et al. 2014). Another severe outbreak occurred in 2003 in Leuven, Belgium, where five children in one family became ill after consuming pasta salad that contained the emetic toxin. The pasta was stored in a refrigerator set at 57°F (14°C), which is significantly higher than the proper storage temperature of 41°F (5°C). The youngest child, a 7-year-old girl, died in the hospital only 13 hours after consuming the pasta (Dierick et al. 2005).

The Centers for Disease Control and Prevention (CDC) estimates that B. cereus caused 63,400 cases of foodborne illness and 20 hospitalizations in the United States each year between 2000 and 2008 (Scallan et al. 2011; CDC 2012). In addition, a 2012 CDC surveillance annual report lists two outbreaks and 24 illnesses involving B. cereus in the United States (Bennett et al. 2014). However, many cases are never reported or diagnosed because the associated symptoms are usually mild and/or short-lasting. Table 1 outlines recent B. cereus foodborne outbreaks.

Preventing Contamination by B. cereus

Because B. cereus endospores are extremely heat-resistant, they can survive cooking temperatures that would otherwise destroy the cells of foodborne pathogens. Additionally, B. cereus spores’ heat resistance increases with salinity (salt presence) and decreases with increasing acidity. Although there is no single temperature that kills B. cereus endospores in all food products, their growth and further contamination can be prevented. Bacillus cereus spores can germinate when exposed to heat or improper handling; therefore, the 2022 Food Code recommends that hot foods be maintained at temperatures 135°F (57°C) or above and cold foods kept at 41°F (5°C) or below (FDA 2022b).

Further research has shown that specific thermal exposure can inactivate B. cereus spores in foods such as rice during cooking (Juneja et al. 2020). To achieve thermal inactivation of B. cereus spores in rice, it must be heated to 195°F (90.5°C) for approximately 256 minutes or to 210°F (99°C) for about 44 minutes. The thermal exposure applied to contaminated rice resulted in a 4-log reduction (99.99% inactivation) of spores. Such cooking temperatures and times may be useful for retail food services to prevent B. cereus spores in cooked rice while minimizing risk to consumers (Juneja et al. 2020). However, the level of heating required can affect rice quality and energy consumption; thus, further research is needed to more precisely target B. cereus spores and their heat resistance.

According to the National Institutes of Health (NIH), the National Institute of Allergy and Infectious Diseases (NIAID), the National Food Processors Association (NFPA), and the FDA 2022 Food Code, the suggestions below represent effective practices to prevent B. cereus growth:

• Steaming under pressure, roasting, frying, and grilling foods can destroy the vegetative cells if temperatures reach at least 145°F (63°C).
• Since foods containing the emetic toxin need to be heated to 249°F (121°C) for more than 80 minutes, reheating foods until they are steaming is not enough to inactivate the emetic toxin, and efforts should be devoted to prevention (Rajkovic 2014).
• Heating (i.e., cooking) to 145°F (63°C) and reheating to 165°F (74°C) for 15 seconds can destroy the vegetative (actively growing) cells. Once cooked, rapid cooling will prevent any present spores from germinating. However, foods cannot be made safe to eat if toxins have already been formed.
• Keep hot foods above 135°F (57°C) and cold foods below 41°F (5°C) to prevent spore germination and bacterial growth (FDA 2022).
• Refrigerate leftovers properly by cooling rapidly to 41°F (5°C) or below. Avoid stacking containers tightly so that air can circulate and cooling occurs quickly (FDA 2022).

Good Practices for Food Product Receiving, Handling, Processing, and Storage

The FDA defines current Good Manufacturing Practices (GMPs) in Title 21, Part 117 of the Code of Federal Regulations (FDA 2022a). These GMPs outline minimum sanitation requirements for FDA-inspected food-handling and processing facilities. It is recommended that more specific, stringent standard operating procedures (SOPs) be developed for each facility. In addition, the sanitation recommendations for food service and retail food facilities outlined in the FDA 2022 Food Code were adopted as law by 7 states (11 state agencies), excluding Florida, as of December 2025 (FDA 2025). The FDA updated the 2017 Food Code with the release of the 2022 Food Code. Since the adoption of updated Food Code versions varies by state, it is important that each facility consult the appropriate state or local regulatory authority to ensure they are using the guidelines required by their jurisdiction. The Florida statutes can be found at https://www.leg.state.fl.us/statutes, Title XXXIII, Chapter 509.

In addition to setting and adhering to strict sanitation requirements, a retail establishment should also develop SOPs for the receiving and storing of food products and ingredients. If food is being processed, appropriate controls and requirements should be established and strictly followed. The FDA 2022 Food Code outlines appropriate processing and cooking requirements for food service.

References

Bennett, S. D., K. Manikonda, E. Mungai, D. Dewy-Mattia, and L. H. Gould. 2014. Surveillance for Foodborne Disease Outbreaks United States, 2012: Annual Report. Centers for Disease and Control Prevention. https://stacks.cdc.gov/view/cdc/23299/cdc_23299_DS1.pdf

Biggel M., et al. 2026. “Foodborne Intoxication Most Likely Linked to Bacillus cereus in a School Canteen Hot Ready-to-Eat Meal.” Journal of Food Production 89(4): 100721. https://doi.org/10.1016/j.jfp.2026.100721

Bottone, E. J. 2010. "Bacillus cereus, a Volatile Human Pathogen." Clinical Microbiology Reviews 23 (2): 382–398. https://doi.org/10.1128/CMR.00073-09

British Columbia Centre for Disease Control (BCCDC). 2002. "Foodborne Illness Outbreaks: Bacillus cereus." Milk Safety Notes. Accessed February 14, 2024. https://www.bccdc.ca/resource-gallery/Documents/Educational%20Materials/EH/FPS/Dairy/Outbreak_Bacillus_Milk.pdf

Carroll, L. M., M. Wiedmann, M. Mukherjee, D. C. Nicholas, L. A. Mingle, and J. Kovac. 2019. “Characterization of Emetic and Diarrheal Bacillus cereus Strains from a 2016 Foodborne Outbreak Using Whole-Genome Sequencing: Addressing the Microbiological, Epidemiological, and Bioinformatic Challenges.” Frontiers in Microbiology 10: 420842. https://doi.org/10.3389/fmicb.2019.00144

Centers for Disease Control and Prevention (CDC). 1986. "Bacillus cereus – Maine." Morbidity and Mortality Weekly Report 35 (25): 408–410. https://www.cdc.gov/mmwr/preview/mmwrhtml/00000754.htm

Centers for Disease Control and Prevention (CDC). 1994. "Epidemiologic Notes and Reports: Bacillus cereus Food Poisoning Associated with Fried Rice at Two Child Day Care Centers—Virginia, 1993." Morbidity and Mortality Weekly Report 43 (10): 177–178. http://www.cdc.gov/mmwr/PDF/wk/mm4310.pdf

Centers for Disease Control and Prevention (CDC). 2012. Pathogens Causing US Foodborne Illnesses, Hospitalizations, and Deaths, 2000–2008. Archived at Wayback Machine, April 28, 2024. https://web.archive.org/web/20240428062156/http://www.cdc.gov/foodborneburden/PDFs/pathogens-complete-list-01-12.pdf

Delbrassinne, L., N. Botteldoorn, M. Andjelkovic, K. Dierick, and S. Denayer. 2015. "An Emetic Bacillus cereus Outbreak in a Kindergarten: Detection and Quantification of Critical Levels of Cereulide Toxin." Foodborne Pathogens and Disease 12 (1): 84–87. https://doi.org/10.1089/fpd.2014.1788

Dierick, K., E. Van Coillie, I. Swiecicka, G. Meyfroidt, H. Devlieger, A. Meulemans, G. Hoedemaekers, L. Fourie, M. Heyndrickx, and J. Mahillon. 2005. "Fatal Family Outbreak of Bacillus cereus-Associated Food Poisoning." Journal of Clinical Microbiology 43 (8): 4277–4279. https://doi.org/10.1128/JCM.43.8.4277-4279.2005

Food and Drug Administration (FDA). 2012. “Bacillus cereus and Other Bacillus spp.” Bad Bug Book: Handbook of Foodborne Pathogenic Microorganisms and Natural Toxins. https://www.fda.gov/downloads/Food/FoodborneIllnessContaminants/UCM297627.pdf

Food and Drug Administration (FDA). 2022a. Code of Federal Regulations Title 21-Part 117—Current Good Manufacturing Practice, Hazard Analysis, and Risk-Based Preventive Controls for Human Food. Accessed February 28, 2024: https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-117

Food and Drug Administration (FDA). 2022b. Food Code 2022. US Public Health Service. Accessed May 12, 2026. https://www.fda.gov/media/164194/download

Food and Drug Administration (FDA). 2025. Adoption of the FDA Food Code by State and Territorial Agencies Responsible for the Oversight of Restaurants and/or Retail Food Stores. https://www.fda.gov/food/fda-food-code/adoption-fda-food-code-state-and-territorial-agencies-responsible-oversight-restaurants-and-retail

Food Standards Australia New Zealand (FSANZ). 2013. Bacillus cereus. Last updated May 2013. https://www.foodstandards.gov.au/sites/default/files/publications/Documents/Bacillus%20cereus.pdf

French National Public Health Agency. 2022. “Nearly 2,000 Outbreaks of Foodborne Illness Were Reported in France in 2022.” French National Public Health Agency (Santé publique France). https://www.santepubliquefrance.fr/en/les-actualites/nearly-2000-outbreaks-foodborne-illness-were-reported-france-2022

Health Protection Surveillance Center (HPSC). 2012. "Bacillus cereus Food-borne Illness." Infectious Intestinal Disease: Public Health and Clinical Guidance. https://www.hpsc.ie/A-Z/Gastroenteric/GastroenteritisorIID/Guidance/File,13492,en.pdf

Juneja, V. K., Osoria, M., Hwang, C.-A., Mishra, A., & Taylor, T.M. 2020. “Thermal Inactivation of Bacillus cereus Spores during Cooking of Rice to Ensure Later Safety of Boudin.” LWT 122: 108955. https://doi.org/10.1016/j.lwt.2019.108955

Manin, A., Souche, A., Simões, P. M., Cassier, P., Barreto, C., & Butin, M. 2026. “Two Years Bacillus cereus Outbreaks: Investigations and Effective Management of Contamination in a Neonatal Intensive Care Unit.” Antimicrobial Resistance & Infection Control 15 (1). https://doi.org/10.1186/s13756-026-01730-x

Marriot, N. G., and R. B. Gravani. 2006. “The Relationship of Microorganisms Sanitation.” Principles of Food Sanitation. 5th ed. Springer Science+Business Media, Inc. https://doi.org/10.1111/j.1541-4329.2006.00004.x

Naranjo, M., S. Denayer, N. Botteldoorn, L. Delbrassinne, J. Veys, J. Waegenaere, N. Sirtaine, et al. 2011. "Sudden Death of a Young Adult Associated with Bacillus cereus Food Poisoning." Journal of Clinical Microbiology 49 (12): 4379–4381. https://doi.org/10.1128/JCM.05129-11

Rajkovic, A. 2014. "Microbial Toxins and Low Level of Foodborne Exposure." Trends in Food Science & Technology 38 (2): 149–157. https://doi.org/10.1016/j.tifs.2014.04.006

Scallan, E., R. B. Hoekstra, F. J. Angulo, R. V. Tauxe, M. A. Widdowson, S. L. Roy, J. L. Jones, and P. M. Griffin. 2011. "Foodborne Illness Acquired in the United States—Major Pathogens." Emerging Infectious Diseases 17 (1): 7–15. https://doi.org/10.3201/eid1701.P11101

Schiel, L., et al. 2026. “Fatal Emetic Bacillus cereus Outbreak Associated with Consumption of Pre-cooked Tortellini, Germany, August to September 2024.” Social Science Research Network (SSRN). https://doi.org/10.2139/ssrn.6487006

Todar, K. 2012. "Bacillus cereus Food Poisoning." In Todar's Online Textbook of Bacteriology. Accessed February 28, 2024. https://textbookofbacteriology.net/B.cereus.html

Whitworth, J. 2023. “Outbreaks down but Illnesses up for Europe in 2023.” Food Safety News (FSN). https://www.foodsafetynews.com/2024/12/outbreaks-down-but-illnesses-up-for-europe-in-2023/

Whitworth, J. 2024. “Norway Solves Outbreak Involving Young Children.” Food Safety News (FSN). https://www.foodsafetynews.com/2024/02/norway-solves-outbreak-involving-young-children/#:~:text=Several%20infants%20aged%205%20to,Meny%20stores%20across%20the%20country

Williams, J. 2011. "Outbreak at Okeechobee Correctional Institute." Food for Thought: An E-Bulletin from the Food and Waterborne Disease Program 1. Florida Department of Public Health. Accessed March 15, 2024. https://outbreakdatabase-com.s3.amazonaws.com/Florida_Dept._of_health_Publication_Food_for_Thought_Issue_1_February_2011_See_page_2.pdf

Zhou, G., K. Bester, B. Liao, Z. Yang, R. Jiang, and N. B. Hendriksen. 2014. "Characterization of Three Bacillus cereus Strains Involved in a Major Outbreak of Food Poisoning After Consumption of Fermented Black Beans (Douchi) in Yunan, China." Foodborne Pathogens and Disease 11 (10): 769–774. https://doi.org/10.1089/fpd.2014.1768