Many babies sickened in ByHeart formula botulism outbreak needed more treatment after hospitalization

Most of the babies hospitalized in a recent nationwide outbreak of infant botulism linked to ByHeart baby formula have needed additional physical therapy and other medical support after going home, according to new data shared April 24.

“Although many infants are now progressing in their recovery, evaluating their outcomes is essential to understanding the progression and severity of illness observed during this outbreak,” said Myra Brooks, a member of the Centers for Disease Control and Prevention’s Epidemic Intelligence Service, who presented the data at the service’s annual conference in Atlanta. The conference highlights the work of the agency’s disease detectives.

Brooks, a first-year EIS officer, works with the CDC’s National Botulism Consultation Service and was part of the response to the outbreak linked to ByHeart infant formula last year. It is the first documented outbreak of infant botulism linked to powdered formula, she noted.

The CDC declared the outbreak over on Feb. 26, with 48 confirmed and probable cases of infant botulism in 17 states that were linked to the baby formula. All of the infants required hospitalization; there were no deaths. All of ByHeart’s Whole Nutrition Infant Formula products were recalled.

Infant botulism is caused by babies ingesting spores of Clostridium botulinum bacteria, which can activate in their intestines and produce a dangerous toxin that can cause muscle weakness and paralysis. Initial symptoms can include difficulty sucking and swallowing, constipation, and loss of head control. Without treatment, breathing difficulties can develop.

Health investigators were able to obtain and review the medical records for 46 of the 48 infants, which showed that most of those who were sickened had moderate to severe disease.

Those with moderate disease, 61% of the infants in the outbreak, required assisted feeding or noninvasive respiratory support, Brooks said. Another 11% of the infants had severe disease. “During hospitalization, these infants experienced respiratory difficulty, requiring intubation or received a surgically placed feeding tube,” she said.

The remaining 28% of infants in the outbreak were classified as having mild disease, although they still needed hospitalization.

While the outbreak cases stayed in the hospital for a median of eight days, some of those with severe disease were hospitalized for more than a month, according to her presentation slides.

For many of the infants sickened in the outbreak, their medical treatments needed to continue after leaving the hospital, Brooks said.

“A third of infants were discharged with nasogastric tubes to supplement feeding, and two-thirds of infants had follow-up orders for physical, speech or occupational therapy,” she said.

The infant botulism outbreak was first identified in early November by the California Department of Public Health, which runs the national infant botulism program that distributes the only FDA-approved drug to treat children sickened by the toxin. The department noticed an increase in medication requests among babies who had consumed ByHeart formula and alerted federal officials.

Outbreak cases continued to rise in the weeks that followed amid delays by retailers in removing recalled formula from store shelves that were compounded by delays by the Food and Drug Administration in sharing information with state food safety officials about where the product was being sold.

While health officials initially thought babies had started falling ill in August 2025, they later identified cases going back to December 2023.

Although ByHeart’s products made up only about 1% of the formula products sold in the United States, the premium organic brand had a loyal following, and the outbreak shook some consumers’ confidence in formula safety generally.

The federal investigation of how ByHeart’s formula became contaminated has in recent months focused on the product’s ingredients. Earlier this year, the FDA announced that tests had detected contamination with Clostridium botulinum — the bacteria that cause infant botulism — in some samples of powdered whole milk used to make the formula.

The FDA has said its investigation into the root cause of the contamination is ongoing, but the agency has not provided any update since Feb. 26.

ByHeart’s media team, in an email to Healthbeat late on April 24, said the company continues to work with the FDA on its investigation. “Our root cause investigation remains ongoing, and we’ll share updates as they become available,” the email said.

This story was produced by Healthbeat and reviewed and distributed by Stacker.