Nara Organics Infant Formula Botulism Outbreak Ends; WGS, Supply Chain Evidence Show Link to ByHeart
Need to Know
- The Nara Organics powdered formula outbreak caused four confirmed infant botulism cases across California, Pennsylvania, and Washington, with all four infants hospitalized and no deaths reported
- Whole genome sequencing linked a clinical C. botulinum isolate from the Nara outbreak to clinical, product base, and finished product samples from the 2025 ByHeart outbreak
- Both outbreaks involved the same organic whole milk and milk powder suppliers, but FDA has not determined whether contamination occurred before or during the drying process.
The multistate infant botulism outbreak linked to Nara Organics Whole Milk Organic Powdered Infant Formula is now over, with new whole genome sequencing (WGS) evidence and supply chain commonalities indicating a common source of contamination between the Nara outbreak and the 2025 outbreak linked to ByHeart infant formula.
The Nara outbreak ended with four confirmed cases of infant botulism across California, Pennsylvania, and Washington. All four infants were hospitalized, and no deaths were reported. Illnesses began between April and May 2026, with the latest onset of illness on May 31. No new cases were added since July 3.
WGS Links Nara and ByHeart Infant Botulism Outbreaks
WGS analysis conducted on clinical Clostridium botulinum isolates and isolates from finished product and ingredient samples revealed genetic relatedness. One C. botulinum isolate from an infant sickened in the Nara outbreak matched a clinical sample from an infant included in the 2025 ByHeart outbreak, as well as a ByHeart powdered infant formula base sample and four samples from unopened cans of ByHeart powdered infant formula.
Based on the new WGS findings, in combination with supply chain evidence, the U.S. Food and Drug Administration (FDA) concluded that there was a common source of contamination between the two outbreaks—organic powdered whole milk from the same supplier and processor.
Specifically, FDA’s traceback investigation suggested that the Nara Organics formula lots linked to the 2026 outbreak were made with milk supplied by Organic West Milk (OWM) and spray-dried by Dairy Farmers of America (DFA). These two companies also respectively supplied and processed the milk and milk powder used in the lots of ByHeart formula implicated in the 2025 outbreak.
Exact Point of Contamination Not Yet Determined
FDA has not yet determined where the contamination of the common organic powdered whole milk ingredient occurred. The agency said there is insufficient evidence to establish whether the milk was contaminated before drying or during the drying process, and its root cause investigation is ongoing.
Previous Evidence Pointed to Shared Ingredient Supply Chain
The earlier ByHeart outbreak ended in February 2026 after 48 infants in 17 states became ill. During that investigation, FDA detected C. botulinum in an organic powdered milk ingredient supplied by OWM and processed by DFA. WGS also linked isolates recovered from the powdered milk to a clinical isolate and contaminated finished formula.
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The connection between the two supply chains emerged during the Nara investigation. It was revealed in June 2026 that, between October 2024 and April 2025, Nara Organics had used OWM milk dried by DFA. FDA later confirmed that the Nara lots linked to illnesses were produced using milk from the same supply chain involved in the ByHeart outbreak. However, at the time, prior to the emergence of the latest WGS findings, FDA said there was not enough evidence to determine whether the OWM/DFA ingredient was the source or route of contamination in the Nara outbreak.
Organic West Milk Provided Incomplete Information During ByHeart Investigation
FDA also previously revealed a traceability gap involving OWM. During its investigation of the ByHeart outbreak, FDA conducted a traceforward investigation to identify other powdered infant formula manufacturers that possibly received OWM milk. At the time, OWM provided an incomplete customer list that did not indicate its milk was supplied to manufacturers of Nara Organics formula. During the Nara investigation, the company informed FDA that the earlier information was incomplete and should have included suppliers to Nara Organics.
Outbreaks Raised Questions About C. botulinum Controls in Infant Formula
The back-to-back outbreaks raised broader questions about how the infant formula industry addresses C. botulinum. The pathogen historically has not been considered a hazard reasonably likely to occur in powdered infant formula manufacturing. Experts who spoke to Food Safety Magazine posited that the outbreaks support reconsidering C. botulinum as a foreseeable hazard requiring targeted preventive controls.
This thought has been echoed at the international level; in July, the Food and Agriculture Organization of the United Nations (FAO)/World Health Organization (WHO) Expert Meetings on Microbiological Risk Assessment (JEMRA) recommended updates to the Codex Alimentarius guidance, Code of Hygienic Practice for Powdered Formula for Infants and Young Children, following a review of emerging microbiological hazards associated with powdered formulas, which was prompted by continued outbreaks and recalls linked to powdered formula.
