Updated August 18, 2026: This article has been updated to reflect the closure of the CDC outbreak investigation, FDA facility inspection findings, the discovery that recalled formula is still appearing in stores, and a new related infant botulism outbreak linked to Nara Organics formula from the same supplier network. Original publish date: June 20, 2025.
An outbreak of infant botulism linked to ByHeart Whole Nutrition Infant Formula sickened 48 infants across 17 US states between December 2023 and November 2025. The CDC declared the outbreak over on February 26, 2026, with a final case count of 28 confirmed and 20 probable cases. All 48 hospitalized infants were treated and no deaths were reported. The recall of all ByHeart products, initiated in November 2025, remains in effect.
Outbreak closed: final case count revised downward
On February 26, 2026, the CDC formally declared the ByHeart infant botulism outbreak over. No new cases had been added since December 10, 2025. After reviewing medical records of all 51 infants initially included in the investigation, public health officials excluded three who were ultimately diagnosed with other illnesses. The final tally is 28 confirmed and 20 probable cases, totaling 48 across 17 states. All 48 infants were hospitalized and treated with BabyBIG (botulism immune globulin); none died. The peer-reviewed outbreak report was published in NEJM Evidence on February 25, 2026.
What the FDA inspections found
As part of its investigation, the FDA inspected ByHeart’s manufacturing facilities and a facility operated by Dairy Farmers of America, which processed Organic West Milk supplied to ByHeart. The FDA identified Clostridium botulinum in a powdered milk ingredient during facility inspections. Whole-genome sequencing analysis matched two samples from one lot of organic whole milk powder from Dairy Farmers of America to a clinical sample from a sick infant and to a positive finished-formula sample. The FDA’s inspections at ByHeart’s own facilities did not identify any deficiencies that could explain the root cause of the outbreak. The root cause investigation remains ongoing, with a focus on dairy ingredients and the supply chain.
On June 3, 2026, ByHeart published an Action Plan outlining corrective steps: new Clostridium botulinum-specific testing protocols, enhanced supplier and ingredient quality assurance, manufacturing facility improvements, and the establishment of an independent Food Safety Advisory Council. The company stated it is working toward safe resumption of infant formula production in cooperation with the FDA.
Recalled formula is still appearing in stores
A significant practical concern has emerged in 2026: recalled ByHeart formula continues to be found for sale at surplus food stores, distressed food handlers, and non-traditional retailers. The Michigan Department of Agriculture and Rural Development issued a warning in March 2026 after finding recalled cans in distressed food outlets across the state. The reason these products are still circulating is their long shelf life. Some recalled batches carry use-by dates of December 1, 2026, meaning a container sitting in a pantry or on a shelf may still appear perfectly fresh and in-date.
Health officials stress that expiration dates do not override recalls. Any ByHeart Whole Nutrition Infant Formula is unsafe regardless of when it was purchased, how it looks, or what date is printed on the can. Parents shopping at discount stores, liquidators, or online resellers should check brand name and recall status, not just expiration date, before using any infant formula. The FDA advises caregivers to photograph the lot code and use-by date before disposal, and to hold the container for 30 days in case a state health department wants to collect it for testing.
A second outbreak: Nara Organics
On June 13, 2026, the FDA and CDC announced a new multistate investigation into infant botulism linked to Nara Organics Whole Milk Organic Powdered Infant Formula. Three confirmed cases have been identified in California, Pennsylvania, and Washington, with illness onset between April and May 2026. The FDA’s traceback investigation determined that the Nara Organics formula lots linked to illness were made with milk supplied by Organic West Milk and spray dried by Dairy Farmers of America, the same supplier network implicated in the ByHeart outbreak.
The FDA noted that Organic West Milk had previously provided an incomplete customer list during the ByHeart investigation that did not indicate milk was supplied to Nara Organics manufacturers. The company has since corrected that disclosure. Whether the two outbreaks share a common contamination event or route has not been confirmed. The Nara Organics investigation is ongoing.
What happened
On November 7, 2025, the Infant Botulism Treatment and Prevention Program (IBTPP) at the California Department of Public Health notified the CDC of a concerning cluster of infant botulism cases, an illness that is normally rare in the United States (about 150 to 180 cases per year, per the CDC). Same-day communication between CDC, FDA, and ByHeart followed. On November 11, 2025, ByHeart initiated a voluntary recall of two batches; on November 19, following its own product testing and further case detection, the company expanded the recall to all batches of ByHeart Whole Nutrition Infant Formula, including both cans and single-serve Anywhere Packs.
ByHeart tested 36 samples across three lots and found Clostridium botulinum Type A in 5 samples spanning all three tested lots. Based on that pattern, ByHeart and the FDA stated they could not rule out that contamination might have affected all ByHeart formula products, prompting the expansion of the recall to the entire product line. Investigators also expanded the case definition, adding 10 earlier infant botulism cases (dating back to December 2023) that had been exposed to ByHeart formula.
What infant botulism is
Infant botulism is a rare but serious illness that occurs when an infant swallows spores of Clostridium botulinum. In infants, whose gut microbiome is still developing, the spores can germinate, colonize the intestinal tract, and produce botulinum neurotoxin, one of the most potent toxins known. The toxin blocks acetylcholine release at neuromuscular junctions, causing progressive descending flaccid paralysis. This mechanism differs from foodborne botulism in adults, in which preformed toxin is directly ingested. Honey has long been recognized as a source and is contraindicated in infants under 12 months. Powdered infant formula had not previously been implicated as a source in a widespread US outbreak.
The regulatory challenge is that botulism spores are dormant and resistant to routine antibacterial testing, requiring specialized culture and molecular assays to detect. Standard microbiological testing of infant formula focuses on live bacteria such as Cronobacter sakazakii and Salmonella. Spore-forming bacteria like Clostridium botulinum can survive typical pasteurization, making them more difficult to eliminate from food processing environments. Testing for C. botulinum spores has not been part of routine formula quality control, and a single negative test cannot rule out contamination given the sporadic distribution of spores in a large batch of powder.
How the illness presents
Infant botulism typically has an insidious onset over hours to days. Constipation is often the earliest sign. Feeding difficulty follows, with a weak suck and swallow. Parents may notice a weaker or altered cry, drooping eyelids, expressionless face, and generalized floppiness. Because the paralysis descends from the cranial nerves to the trunk and limbs, respiratory muscles can be affected in more advanced cases, at which point the illness is a medical emergency. Symptoms typically appear within 30 days of exposure to spores. BabyBIG (botulism immune globulin intravenous) is available through the California IBTPP for infants with confirmed or highly suspected infant botulism, and early treatment shortens hospital stay and reduces the risk of complications.
What parents should do now
Parents should stop using any ByHeart Whole Nutrition Infant Formula immediately, regardless of lot number or expiration date. Botulinum toxin cannot be detected by sight or smell. Before discarding, photograph or record the lot number and use-by date printed on the bottom of the container. Keep the container in a marked location for approximately 30 days in case it is needed for testing, then dispose of according to local guidance. Bottles, utensils, and surfaces that contacted the formula should be cleaned in hot, soapy water. ByHeart is offering refunds; parents can contact the company through its website or by phone at 866-201-9069.
If an infant has been fed ByHeart formula and shows any early signs of infant botulism (constipation, poor feeding, weak cry, drooping eyelids, or generalized floppiness), contact a pediatrician or emergency department promptly. Do not dilute formula with additional water to stretch supply, and do not attempt to prepare homemade formula. Pediatricians can help identify alternative safe formulas.
The wider context
The ByHeart outbreak is the first known infant botulism outbreak in the United States linked to infant formula. The FDA has launched a series of post-outbreak activities, including surveillance sampling of powdered milk from suppliers, engagement with international food safety bodies to conduct updated risk assessments on spore-forming pathogens in powdered infant formula, and a letter sent to the infant formula industry on July 13, 2026, calling for increased vigilance over ingredient and supply chain safety. The emergence of a second outbreak linked to the same supplier network in 2026 has intensified scrutiny of organic whole milk powder as a potential contamination vector and raised questions about the completeness of supplier disclosure during outbreak investigations.
- U.S. Food and Drug Administration. Post-Outbreak Response Activities: Clostridium botulinum Illnesses Associated with Consumption of Powdered Infant Formula. Updated July 13, 2026. fda.gov.
- Centers for Disease Control and Prevention. Investigation Update: Infant Botulism Outbreak, November 2025. February 26, 2026. cdc.gov.
- Chung CH, et al. Multistate Infant Botulism Outbreak Associated with Powdered Infant Formula. NEJM Evidence. February 25, 2026.
- U.S. Food and Drug Administration. ByHeart Updates Information Regarding Voluntary Recall of all Batches of ByHeart Whole Nutrition Infant Formula. November 19, 2025. fda.gov.
- Michigan Department of Agriculture and Rural Development. MDARD Continues to Find Recalled ByHeart Infant Formula Available for Sale. March 2, 2026. michigan.gov.
- U.S. Food and Drug Administration. Outbreak Investigation: Infant Botulism Linked to Powdered Infant Formula, June 2026 (Nara Organics). fda.gov.