An Unexpected—and Unprecedented—Crisis: Lessons Learned From the Largest Infant Botulism Outbreak Linked to Powdered Infant Formula

There’s been a spate of infant botulism cases tied to powdered infant formula in the news lately.

In the spring, four infants in three different states were sickened with a strain of botulism that investigators linked to Nara Organics Whole Milk Organic Infant Formula. The company has voluntarily recalled the product and the US Centers for Disease Control and Prevention (CDC), US Food and Drug Administration (FDA), California Department of Public Health’s Infant Botulism Treatment and Prevention Program (CDPH IBTPP) and other public health partners are conducting investigations.

This outbreak follows a larger, unprecedented one that made headlines late last year when 28 confirmed and 20 suspected cases of infant botulism were tied to ByHeart Whole Nutrition Infant Formula products. Those products were also recalled and FDA investigations—which are still ongoing—identified Clostridium botulinum (C. bot) in a powdered milk ingredient used to make the formula.

State and federal partners discussed details of the ByHeart investigation in a question-and-answer panel session moderated by Anthony Tran, DrPH, director of the State Public Health Laboratory, CDPH, and presented at the 2026 APHL Annual Conference, held in Baltimore in May. See what lessons were learned from this unexpected crisis.

When did you first know there was a problem?

Jessica Khouri, MD, senior medical officer at the CDPH, explained that IBTPP, the only producer and distributor—both nationally and internationally—of BabyBIG, the drug used to treat infant botulism, provides 24/7 case consultation worldwide to healthcare providers caring for a patient with suspected infant botulism. She noted that those case consultations and the deployment of BabyBIG serve as an infant botulism surveillance system.

Around mid-fall, IBTPP had identified an increase in cases. Khouri told the audience that three babies across the country were hospitalized and lab results confirmed the presence of Type A botulism. Epidemiological investigations determined that all three had been exposed to powdered infant formula from the same manufacturer—ByHeart.

“We immediately identified this cluster and notified our federal partners—CDC and FDA,” Khouri said. “An email went out on Wednesday, November 5, with additional data provided on Thursday, November 6. By Friday, November 7, we had mobilized an outbreak response, and by Saturday, we were on calls with the manufacturer and our partners. This all occurred during the Veteran’s Day holiday weekend and during a federal shutdown. The response was that rapid.”

How was testing conducted?

Carolina Luquez, PhD, team lead of CDC’s National Botulism Laboratory, Enteric Diseases Laboratory Branch, noted that CDC sequenced isolates from clinical and food specimens as part of routine testing and uploaded data to PulseNet, so scientists could look for genomic similarities that would indicate cases are related.

FDA’s Kari Irvin, deputy office director, Human Foods Program/CORE+EP, emphasized the important role that laboratories in the Laboratory Flexible Funding Model (LLFM) program played in the response. LLFM labs, with FDA funding, provide crucial food safety surveillance and testing to assist the FDA in protecting the nation’s food supply.

“Regulatory science and research science move at different paces,” she said. “For the FDA to adopt newer, rapid methodology, it requires validation and approval. But the LLFM labs are able to use methodologies that may not have been validated by FDA labs. The methodology that they were able to employ with their own in-house validation enabled them to pick up screening results, which prompted us to go back and look at a base mix lot code. There was a lot of complex, constant communication happening.”

How did the Maryland State Public Health Laboratory gear up for a surge in C. bot testing?

Sin Urban, PhD, chief of the Division of Environmental Sciences Laboratories Administration at the Maryland Department of Health, explained that while Maryland had the reagents and method for botulism testing in place, enrichment was a problem. The cans of powdered infant formula the lab received were very large—680 grams. But the testing methods were written for 1-to-2 grams. “We knew that the contamination was at a very low level of spores,” Urban said. “For one can, you would need to set up 680 tests. You can’t work that way.”

When Urban heard that California had set up a method for enriching 100 grams, he requested it; a day later, the Maryland lab received it. “Those pre-formed relationships are key,” he said. “When you have them, the dots connect.”

Have you found any raw materials that were implicated in the outbreak?

Because infant powdered formula is made from a base mix with hundreds of different ingredients, finding the source of contamination is extremely challenging, said Irvin.

“When we started the investigation, all we had was an epidemiological signal—that all these sick babies consumed this specific brand of formula,” Irvin said. “Then we started learning it wasn’t one or two lot codes; it was sporadic lot codes. So now we know we have sporadic contamination. Then when you trace back each of those finished lot codes, you learn they’re manufactured from a base mix lot code, and each of those base mixes is composed of hundreds of ingredients with many different lot codes. Tracing back the ingredient supply chain, we began to focus on some of the ingredients that were most suspicious to our subject matter experts. And those were the dairy-based dry ingredients.”

Irvin noted that when whole genome sequencing was initiated on clinical and dry milk powder samples, investigators found 17 different strains of C. bot.

“This is a complex contamination event,” she said. “Was it the formulation of the product? What happened on the dairy farms that supply the milk? We don’t know. The lab testing isn’t finished, and it will be a long time before we identify a root cause.”

Looking back, what do you think worked well during the investigation?

All the panelists mentioned communication, collaboration and coordination.

“I think this outbreak response really highlighted the close collaboration we have with our federal, state, local and jurisdictional partners,” said Khouri. “The communication and coordination really worked well,” she added, “and we felt the support we needed being on the frontlines.”