"As of February 26, 2026, two isolates from one lot of organic whole milk powder, collected and analyzed by FDA, have been shown by whole genome sequencing (WGS) analysis to match a cluster of isolates reported by FDA on January 23, 2026. These two new isolates were collected by FDA at Dairy Farmers of America, the processor for Organic West Milk, which supplies ByHeart."
"The detection of Clostridium botulinum in infant formula, or ingredients, is complex. To date, WGS analysis has identified 17 different strains of this bacterium in samples from patients, finished products, and ingredients. While these sample results add to the available evidence needed to investigate the root cause of this outbreak, due to the complexities of Clostridium botulinum and limited scientific evidence currently available, FDA has not yet determined a root cause(s)."Case Counts
Total Illnesses: 48
Confirmed cases: 28
Probable cases: 20
Hospitalizations: 48
Deaths: 0
Last Illness Onset: November 29, 2025
States with Cases: AZ, CA, ID, IL, KY, MA, MI, MN, NC, NJ, OR, PA, RI, TX, VA, WA, WI
Product Distribution: Online and nationwide (including Guam and Puerto Rico), and internationally
https://www.fda.gov/food/outbreaks-foodborne-illness/outbreak-investigation-infant-botulism-infant-formula-november-2025
Outbreak Investigation of Infant Botulism: Infant Formula (November 2025)
CDC declares this outbreak over. FDA’s investigation into the root cause is ongoing.
Product:
All ByHeart Whole Nutrition Infant Formula products have been recalled. This includes all lots of ByHeart formula cans and single-serve “anywhere pack” sticks.
ByHeart infant formula products make up approximately 1% of all infant formula sold in the United States and this outbreak does not create shortage concerns of infant formula for parents and caregivers.
Current Update
February 26, 2026
The FDA and CDC, in collaboration with the California Department of Public Health (CDPH), Infant Botulism Treatment and Prevention Program (IBTPP), and other state and local partners, investigated a multistate outbreak of infant botulism. Epidemiologic and laboratory analyses indicated that ByHeart Whole Nutrition infant formula is the source of this multistate outbreak of infant botulism.
As of February 26, 2026, CDC declares the outbreak over. During recent weeks, public health officials at state and local health departments, IBTPP, and CDC reviewed the medical records of the 51 infants who were initially included in the investigation and used additional criteria to further describe the cases. Since December 10, 2025, no new cases were added, and 3 previously reported cases from 3 states were ultimately diagnosed with other illnesses and excluded from the case count. As of February 26, 2026, the investigation includes 28 cases of confirmed infant botulism and 20 cases of probable infant botulism. Refer to CDC’s Food Safety Alert for definitions of confirmed and probable cases.
As of February 26, 2026, two isolates from one lot of organic whole milk powder, collected and analyzed by FDA, have been shown by whole genome sequencing (WGS) analysis to match a cluster of isolates reported by FDA on January 23, 2026. These two new isolates were collected by FDA at Dairy Farmers of America, the processor for Organic West Milk, which supplies ByHeart. This cluster now also includes:
- one closed powdered infant formula sample (tested by ByHeart),
- one closed powdered infant formula sample (tested by the New York State Department of Health, Wadsworth Laboratory),
- one clinical isolate,
- three isolates from one lot of organic whole milk powder (tested by ByHeart).
One clinical isolate matches a cluster that now includes:
- three clinical isolates and
- an open powdered infant formula sample (tested by CDPH and previously reported as confirmed positive on November 18, 2025)
The second recently analyzed clinical isolate matches a cluster that now includes:
This outbreak is no longer ongoing, and FDA is transitioning from its initial response activities, managed by FDA’s Office of Coordinated Outbreak Response, Evaluation & Prevention (CORE+EP) which focused on containing the event so that no additional illnesses occurred. The agency is now focused on post-incident response actions and activities, which may include additional surveillance, as well as prevention and compliance activities.
FDA will continue investigating the root cause(s) and future updates will be reported on FDA’s Actions to Respond to Clostridium botulinum Illnesses Associated with Consumption of Powdered Infant Formula. This webpage will be updated with specific information on FDA’s ongoing efforts to ensure the safety of powdered infant formula, including general information about formula safety.
https://www.fda.gov/food/outbreaks-foodborne-illness/fdas-actions-respond-clostridium-botulinum-illnesses-associated-consumption-powdered-infant-formula
FDA’s Actions to Respond to 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. The 2025 infant botulism outbreak is unique with a spike in illnesses associated with a particular infant formula, and both FDA and the firm, ByHeart, Inc. (ByHeart) are conducting root cause investigation. At this time, the investigation has not indicated a broader problem in the infant formula supply.
This is the first known botulism outbreak tied to infant formula anywhere in the world since infant botulism was first described as a distinct clinical entity almost 50 years ago. As a result of this outbreak, FDA is working with international experts and standard setting bodies to conduct a risk assessment on Clostridium botulinum in infant formula, which will consider all available data.
The FDA and our partners will remain vigilant for any signs that infants are becoming ill from formula exposure from any cause. As we did in this case, if we detect such a signal, FDA will act swiftly to protect our most vulnerable population.
Bacterial spores, including Clostridium botulinum spores, are known to be present at low levels in many foods. Infants might ingest Clostridium botulinum spores from their food or environment. These spores are generally harmless to older children and adults with mature, healthy digestive systems. However, they can pose a life-threatening risk to infants who ingest viable spores that produce a toxin that affects 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. Additionally, the mere presence of spores alone may not be determinative of risk, as not all spores are viable and cause illness.
Spore-forming bacteria analysis and laboratory detection methods differ from traditional pathogen detection methods requiring 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 FDA continues to respond to the 2025 infant botulism outbreak and implements risk reduction strategies going forward.
Overview of recent Clostridium botulinum illnesses and contamination of powdered infant formula
FDA and CDC, in collaboration with the California Department of Public Health (CDPH) Infant Botulism Treatment and Prevention Program (IBTPP) and other state and local partners, are investigating a multistate outbreak of infant botulism linked to ByHeart Whole Nutrition infant formula. FDA and CDC issued warnings about ByHeart infant formula in November 2025, after CDPH IBTPP reported an increase in the number of botulism infections among infants consuming ByHeart powdered infant formula.
CDC has identified 51 infants from 19 states with suspected or confirmed infant botulism and confirmed exposure to ByHeart Whole Nutrition infant formula. This includes the expanded case count from December 24, 2023, to December 1, 2025. All 51 infants were hospitalized, and no deaths attributed to this outbreak have been reported to date. FDA first became aware of this cluster of illnesses on November 6, 2025, and immediately began its investigation. On November 7, 2025, after consulting with CDC, CDPH, and partners in states with ill infants, the FDA spoke with the firm to recommend voluntary recall and on November 8, 2025, the FDA issued a public warning to consumers. The recall was subsequently expanded on November 11, 2025 to include all lots of infant formula produced by ByHeart.
All ByHeart infant formula products have been recalled, and these products should not be available for sale in stores or online. This includes all formula cans and single-serve “anywhere pack” sticks. As part of this investigation, ByHeart, FDA, and state laboratories have tested unopened containers of ByHeart infant formula and raw materials used in making ByHeart infant formula. On November 8, 2025, preliminary laboratory results reported by CDPH suggested the presence of Clostridium botulinum in an open can of ByHeart infant formula that was fed to an infant with diagnosed botulism. On November 20, 2025, ByHeart reported that third-party laboratory analysis of some samples of unopened infant formula products retained at its facility identified Clostridium botulinum.
Testing is ongoing by FDA, CDC, state partners, and ByHeart. The majority of FDA samples have preliminarily tested negative for the presence of Clostridium botulinum; all finished product positives are being reported in the Outbreak Advisory.
Actions FDA is taking to respond to the 2025 infant botulism outbreak:
Continued investigation to learn more about the root cause of the outbreak.
Initiated a sampling assignment focused on dairy-based ingredients, including whole milk powder, non-fat dry milk powder, and whey protein concentrate to help evaluate the supply chain and inform next steps.
Broaden scientific knowledge and understanding of Clostridium botulinum and public health interventions for controlling it.
Enhance communications and engagement with industry, consumers, federal, state, local, and other public health partners about infant formula safety.
Collaborate with stakeholders on what could be done to enhance safety: FDA continues to have ongoing collaboration with industry members, coalition groups, academia, and consumers/consumer groups, to discuss and engage in dialogue to better understand risks associated with Clostridium botulinum and best practices for the manufacturing of powdered infant formula.
On March 8, 2023, FDA issued a Letter to Industry on areas of concern based on inspections of powdered infant formula manufacturing facilities. The FDA emphasized that manufacturers must identify and consider all known or reasonably foreseeable biological hazards associated with powdered infant formula, including Clostridium botulinum.
Conduct and support research to help fill knowledge gaps in the scientific understanding of Clostridium botulinum: 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. 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.
Future risk assessment and scientific review activities will depend on the findings of our ongoing investigation. FDA will evaluate the need for additional risk assessment work as we gather more information about the 2025 infant botulism outbreak and its contributing factors. FDA welcomes any and all scientific evidence that can inform recommendations on this important public health matter.
- one clinical isolate,
- four isolates from one lot of powdered infant formula (tested by ByHeart and previously reported in FDA’s January 23, 2026 update) (This lot was reported by one patient), and
- one sample of base mix used to make powdered infant formula (tested by ByHeart)
This outbreak is no longer ongoing, and FDA is transitioning from its initial response activities, managed by FDA’s Office of Coordinated Outbreak Response, Evaluation & Prevention (CORE+EP) which focused on containing the event so that no additional illnesses occurred. The agency is now focused on post-incident response actions and activities, which may include additional surveillance, as well as prevention and compliance activities.
FDA will continue investigating the root cause(s) and future updates will be reported on FDA’s Actions to Respond to Clostridium botulinum Illnesses Associated with Consumption of Powdered Infant Formula. This webpage will be updated with specific information on FDA’s ongoing efforts to ensure the safety of powdered infant formula, including general information about formula safety.
https://www.fda.gov/food/outbreaks-foodborne-illness/fdas-actions-respond-clostridium-botulinum-illnesses-associated-consumption-powdered-infant-formula
FDA’s Actions to Respond to 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. The 2025 infant botulism outbreak is unique with a spike in illnesses associated with a particular infant formula, and both FDA and the firm, ByHeart, Inc. (ByHeart) are conducting root cause investigation. At this time, the investigation has not indicated a broader problem in the infant formula supply.
This is the first known botulism outbreak tied to infant formula anywhere in the world since infant botulism was first described as a distinct clinical entity almost 50 years ago. As a result of this outbreak, FDA is working with international experts and standard setting bodies to conduct a risk assessment on Clostridium botulinum in infant formula, which will consider all available data.
The FDA and our partners will remain vigilant for any signs that infants are becoming ill from formula exposure from any cause. As we did in this case, if we detect such a signal, FDA will act swiftly to protect our most vulnerable population.
Bacterial spores, including Clostridium botulinum spores, are known to be present at low levels in many foods. Infants might ingest Clostridium botulinum spores from their food or environment. These spores are generally harmless to older children and adults with mature, healthy digestive systems. However, they can pose a life-threatening risk to infants who ingest viable spores that produce a toxin that affects 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. Additionally, the mere presence of spores alone may not be determinative of risk, as not all spores are viable and cause illness.
Spore-forming bacteria analysis and laboratory detection methods differ from traditional pathogen detection methods requiring 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 FDA continues to respond to the 2025 infant botulism outbreak and implements risk reduction strategies going forward.
Overview of recent Clostridium botulinum illnesses and contamination of powdered infant formula
FDA and CDC, in collaboration with the California Department of Public Health (CDPH) Infant Botulism Treatment and Prevention Program (IBTPP) and other state and local partners, are investigating a multistate outbreak of infant botulism linked to ByHeart Whole Nutrition infant formula. FDA and CDC issued warnings about ByHeart infant formula in November 2025, after CDPH IBTPP reported an increase in the number of botulism infections among infants consuming ByHeart powdered infant formula.
CDC has identified 51 infants from 19 states with suspected or confirmed infant botulism and confirmed exposure to ByHeart Whole Nutrition infant formula. This includes the expanded case count from December 24, 2023, to December 1, 2025. All 51 infants were hospitalized, and no deaths attributed to this outbreak have been reported to date. FDA first became aware of this cluster of illnesses on November 6, 2025, and immediately began its investigation. On November 7, 2025, after consulting with CDC, CDPH, and partners in states with ill infants, the FDA spoke with the firm to recommend voluntary recall and on November 8, 2025, the FDA issued a public warning to consumers. The recall was subsequently expanded on November 11, 2025 to include all lots of infant formula produced by ByHeart.
All ByHeart infant formula products have been recalled, and these products should not be available for sale in stores or online. This includes all formula cans and single-serve “anywhere pack” sticks. As part of this investigation, ByHeart, FDA, and state laboratories have tested unopened containers of ByHeart infant formula and raw materials used in making ByHeart infant formula. On November 8, 2025, preliminary laboratory results reported by CDPH suggested the presence of Clostridium botulinum in an open can of ByHeart infant formula that was fed to an infant with diagnosed botulism. On November 20, 2025, ByHeart reported that third-party laboratory analysis of some samples of unopened infant formula products retained at its facility identified Clostridium botulinum.
Testing is ongoing by FDA, CDC, state partners, and ByHeart. The majority of FDA samples have preliminarily tested negative for the presence of Clostridium botulinum; all finished product positives are being reported in the Outbreak Advisory.
Actions FDA is taking to respond to the 2025 infant botulism outbreak:
Continued investigation to learn more about the root cause of the outbreak.
Initiated a sampling assignment focused on dairy-based ingredients, including whole milk powder, non-fat dry milk powder, and whey protein concentrate to help evaluate the supply chain and inform next steps.
Broaden scientific knowledge and understanding of Clostridium botulinum and public health interventions for controlling it.
Enhance communications and engagement with industry, consumers, federal, state, local, and other public health partners about infant formula safety.
Collaborate with stakeholders on what could be done to enhance safety: FDA continues to have ongoing collaboration with industry members, coalition groups, academia, and consumers/consumer groups, to discuss and engage in dialogue to better understand risks associated with Clostridium botulinum and best practices for the manufacturing of powdered infant formula.
On March 8, 2023, FDA issued a Letter to Industry on areas of concern based on inspections of powdered infant formula manufacturing facilities. The FDA emphasized that manufacturers must identify and consider all known or reasonably foreseeable biological hazards associated with powdered infant formula, including Clostridium botulinum.
Conduct and support research to help fill knowledge gaps in the scientific understanding of Clostridium botulinum: 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. 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.
Future risk assessment and scientific review activities will depend on the findings of our ongoing investigation. FDA will evaluate the need for additional risk assessment work as we gather more information about the 2025 infant botulism outbreak and its contributing factors. FDA welcomes any and all scientific evidence that can inform recommendations on this important public health matter.
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