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  1. Outbreaks of Foodborne Illness

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Post-Outbreak Response Activities: Clostridium botulinum Illnesses Associated with Consumption of Powdered Infant Formula

Infant botulism is a rare but serious illness caused by spores from a bacterium called Clostridium botulinum. These spores are naturally found in the environment including in soil and sediments (dust) and can enter manufacturing facilities and home environments from hands, shoes, and other contaminated surfaces. 

Overview of recent Clostridium botulinum illnesses and contamination of powdered infant formula

ByHeart

From late 2025 through early 2026, the FDA and CDC, in collaboration with the California Department of Public Health (CDPH)’s Infant Botulism Treatment and Prevention Program (IBTPP) and other state and local partners, investigated a multistate outbreak of infant botulism. In total, 48 infants became ill across 17 states. On February 26, 2026, the CDC declared the outbreak over and FDA’s inspections at the ByHeart facilities also concluded.

As a part of FDA’s investigation, we inspected ByHeart's manufacturing facilities. These inspections led to the identification of Clostridium botulinum in a powdered milk ingredient. The inspections at the ByHeart facilities did not identify any additional factors that could explain the cause of this outbreak.

The FDA  also conducted an inspection at Dairy Farmers of America (the processor for Organic West Milk, which was a supplier to ByHeart). FDA and ByHeart sampled dairy ingredients from Dairy Farmers of America. Two samples from one lot of organic whole milk powder were shown by whole genome sequencing (WGS) analysis to match a clinical sample and a positive infant formula sample. The FDA's investigation into the root cause is ongoing with a focus on ingredients.  

Additional details about the outbreak can be found on the Outbreak Investigation page. 

Nara Organics

On June 13, 2026, the FDA and CDC, in collaboration with the CDPH IBTPP, and other state and local partners, announced an investigation into a multistate outbreak of infant botulism illnesses linked to Nara Organics Whole Milk Organic Powdered Infant Formula.

The FDA later announced that through its traceback investigation it has been determined that the Nara Organics infant formula lots linked to illnesses in this outbreak were made with milk supplied by Organic West Milk and spray dried by Dairy Farmers of America. While these are the same suppliers of organic whole milk and organic whole milk powder from the outbreak of infant botulism linked to ByHeart Powdered Infant Formula in November 2025, currently there is not enough evidence to determine if this is the source or route of contamination.

Further, FDA conducted a trace-forward investigation during the 2025 outbreak to determine if Organic West Milk supplied milk to any other powdered infant formula manufacturers. At that time, Organic West Milk provided an incomplete customer list that did not indicate that their milk was supplied to manufacturers of Nara Organics infant formula. As part of the current investigation, Organic West Milk informed FDA that the customer information previously provided was incomplete and should have included suppliers to Nara Organics.  

FDA continues to work with the firms included in the 2026 investigation to determine the root cause of the Nara Organics outbreak and if any additional products are impacted.

FDA’s investigation is ongoing and more information will be posted to the outbreak advisory page as it becomes available.

FDA’s Ongoing Post-Response Activities

The FDA has transitioned from its initial response activities associated with the 2025 outbreak and is now focused on post-outbreak response actions and activities to help prevent future illnesses, which include:

  • Continued investigation into the root cause of the 2025 outbreak, including assessment of the supply chain and dairy-based ingredients. 
  • Surveillance sampling to better assess the presence of Clostridium botulinum in powdered milk. 
    • In February 2026, as an initial surveillance sampling assignment, the FDA collected 48 powdered milk samples from four suppliers to infant formula manufacturers (12 samples per supplier). Of the 48 samples, 46 were negative by polymerase chain reaction (PCR) and did not undergo any additional testing. The remaining 2 samples, both organic nonfat milk powder, tested positive by PCR and were further processed and analyzed using whole genome sequencing (WGS).
    • WGS results confirmed the presence of Clostridium sporogenes with a gene highly associated with botulinum toxin B1. This suggests – but does not confirm – that the bacterium could produce botulinum toxin in certain environmental conditions. Both sequences were nearly identical (≤3 substitution differences), and both samples were acquired at the same firm. Importantly, FDA confirmed that the powdered milk was not used to manufacture infant formula.  All sequences have been uploaded to the National Center for Biotechnology Information (NCBI) and were not a match for any clinical or non-clinical sequences previously reported.
    • While the results from this initial sampling assessment do not provide a link to the root cause of the infant formula contamination, they can inform the Agency’s continued post-outbreak response actions and understanding of Clostridium botulinum as an emerging risk in the context of infant formula production.
  • Efforts to understand risks associated with Clostridium botulinum and best practices for the manufacturing of powdered infant formula.
    • The FDA advocated for the Joint FAO/WHO Expert Meeting on Microbiological Risk Assessment (JEMRA) to conduct a risk assessment on spore-forming pathogens, including Clostridium botulinum and Bacillus cereus, in powdered infant formula.
    • The FDA has also supported the Codex Committee on Food Hygiene request to JEMRA to 1) update the existing risk assessment and scientific advice on Cronobacter and Salmonella in powdered infant formula and 2) provide other relevant scientific advice that would inform recommendations on strengthened control measures across infant formula production, covering all stages from primary production and packaging to the reconstitution of the product and including environmental monitoring.
    • The FDA engaged with Cornell University’s Pathogenic Spore Consortium, a cohort of leaders across academia and industry addressing the risks posed by spore forming bacteria in dairy foods production, as they develop strategies and training to reduce the presence of Clostridium botulinum and other spore-formers in milk.
    • The FDA has requested the International Commission on Microbiological Specifications for Foods (ICMSF) to consider revisiting its publication “Usefulness of testing for Clostridium botulinum in powdered infant formula and dairy-based ingredients for infant formula” given the recent infant botulism outbreak in the U.S.
  • Communications and engagement with industry, consumers, federal, state, local, and other public health partners about enhancing infant formula safety.
    • On July 13, 2026, the FDA sent a letter to the infant formula industry highlighting risks that manufacturers should consider when selecting ingredients and ingredient sources for powdered infant formula production and called on industry to practice increased vigilance to ensure ingredient and infant formula safety.

The FDA will continue to update this page with additional actions that occur related to FDA’s efforts to prevent future infant botulism illnesses linked to consumption of powdered infant formula.

Infant Botulism

Infant botulism is a rare but serious illness caused by toxin from a bacterium called Clostridium botulinum. Spores from this bacterium are naturally found in the environment including in soil and sediments (dust).  They can enter manufacturing facilities and home environments from hands, shoes, and other contaminated surfaces. 

Clostridium botulinum spores are generally harmless to older children and adults with mature, healthy digestive systems. However, they can pose a life-threatening risk to infants. When ingested, spores begin to grow and produce toxin, which interferes with the nervous system.

There are fundamental differences between bacteria that form spores like Clostridium botulinum and those that do not, such as Cronobacter and Salmonella. These differences are crucial to understanding food safety contamination risks and assessing testing strategies.

  • Non-spore-forming bacteria (e.g., Cronobacter and Salmonella) do not form protective spores.  While dangerous, they are susceptible to pasteurization.
  • Spore-forming bacteria (e.g., Clostridium botulinum) are incredibly resilient.  They can create a protective spore that allows them to survive typical pasteurization and harsh environmental conditions for long periods. This makes the spores more difficult to eliminate from food processing environments.  
  • Spore-forming bacteria analysis and laboratory detection methods differ from traditional pathogen detection methods. They require additional time and specialized resources, which limits the number of labs with testing capacity.  The complex testing process can take two or more weeks for final results.

These two categories of bacteria present distinct contamination risks and require different prevention and testing strategies due to their vastly different survival capabilities and environmental presence. These are important considerations as the FDA considers risk reduction strategies going forward.    
 

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