Clostridial Spores Present Food Safety Control Challenges

Clostridia are commonly found in foods and environmental sources. Unlike many other bacterial foodborne pathogens, clostridia produce spores that can survive harsh conditions and persist for years, potentially decades, in farm and food processing environments.

The spores are also resistant to common food safety interventions, including cooking, pasteurization, and certain sanitizers. FAO emphasized that food producers, processors, handlers, and consumers should minimize spore contamination and prevent clostridial growth in foods to reduce foodborne disease risks.

C. botulinum and C. perfringens are recognized foodborne pathogens. Although C. difficile spores have been isolated from some foods, FAO said evidence supporting classification of C. difficile infection as a foodborne illness remains weak.

Botulism Rare but Potentially Fatal

Foodborne botulism is rare but can cause severe and potentially fatal neuroparalytic disease through ingestion of preformed BoNT in improperly preserved or insufficiently chilled foods. According to the report, consumption of as little as 50 nanograms of BoNT can cause severe and potentially fatal intoxication.

Beyond eliminating spores through appropriate canning processes, established controls for preventing growth of BoNT-producing clostridia include strict temperature control, salt addition, pH reduction, decreased water activity, nitrite application, and inhibitory food ingredients.

FAO also addressed infant and adult intestinal botulism, which occur when ingested spores colonize the intestines and produce toxin. Although the source of spores is often unknown, honey, dust, and soil have been associated with infant botulism.

Other Clostridium species, including C. butyricum, C. baratii, and some C. sporogenes, can also produce BoNTs, but FAO said their foodborne significance and public health burden remain poorly defined.

Temperature Control Key to Preventing C. perfringens

In contrast to the rarity of foodborne botulism, C. perfringens infection is among the most common, although often underreported, causes of foodborne gastrointestinal illness. Outbreaks are frequently associated with mass catering operations.

Illness can occur when temperature abuse allows vegetative cells of C. perfringens to multiply to high levels in food. After the food is consumed, the cells sporulate in the large intestine and release enterotoxin.

FAO emphasized strict temperature control during cooling, hot-holding, and reheating, as well as inhibitory product formulations, as important measures for preventing C. perfringens proliferation in high-risk foods.

Global Data Gaps Complicate Disease Burden Estimates

FAO noted that estimates of the incidence and burden of foodborne diseases related to clostridia are predominantly derived from high-income countries, leaving significant gaps in understanding their global epidemiology.

The report estimated severe foodborne botulism at 1,036 disability-adjusted life years (DALYs), with an estimated cost of $1.68 million per case. C. perfringens illness accounted for an estimated 6,963 DALYs in European and low-mortality countries and ranked as the second most common cause of bacterial-associated foodborne illness in the U.S., with an estimated annual economic burden of $342.7 million.

The annual costs of C. difficile infection were estimated at €3.4 billion in Europe and $5.9 billion in the U.S. However, FAO underscored that, despite the biological plausibility of food or the environment serving as vehicles for C. difficile spores, evidence is presently insufficient to classify the disease as a traditional foodborne illness.

Unprecedented: C. botulinum in Infant Formula

“Unprecedented” infant botulism outbreaks that occurred in the U.S. in 2025 and 2026, linked to contaminated ByHeart and Nara Organics brand formulas, respectively, were acknowledged in the report. In the former outbreak, which sickened nearly 50 babies in 17 states, C. botulinum was found in powdered organic whole milk used as an ingredient in the formula.

These outbreaks have spurred national and global discussions about whether clostridia should be treated as a foreseeable hazard in infant formula requiring targeted preventive controls. For example, in July 2026, FAO and the World Health Organization’s (WHO’s) Joint Expert Meetings on Microbiological Risk Assessment (JEMRA) recommended updating the Codex Alimentarius guidance on hygienic practice for powdered infant formula to include BoNT-producing clostridia as a priority hazard.