ByHeart infant botulism outbreak ends with 48 babies sickened

By: The Associated Press Posted: 10:51 AM CST Thursday, Feb. 26, 2026

ATLANTA (AP) — A rare outbreak of infant botulism that sickened dozens of babies who drank recalled ByHeart formula is over, with no new cases reported since mid-December, the U.S. Centers for Disease Control and Prevention said Thursday.

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In all, 48 babies were sickened since 2023. That’s actually down from the previous case count, because three infants were ultimately diagnosed with other illnesses not tied to botulism, health officials said.

All of the children who got sick were hospitalized. No deaths have been reported.

FILE - A container of ByHeart baby formula, in Flagstaff, Ariz., on Wednesday, Nov. 12, 2025. (AP Photo/Cheyanne Mumphrey, File)

It’s still unclear exactly how, when or where the organic, whole-milk powdered baby formula became contaminated with the type of bacteria that can cause serious illness, paralysis and death in children younger than 1, health officials added.

Most of the cases had occurred since August, when officials at California’s Infant Botulism Treatment and Prevention program detected an alarming rise in reports of the illness in babies who consumed ByHeart formula.

ByHeart, based in New York, initially recalled two lots of formula in early November, but the company expanded the recall to all products days later. Federal health officials later said they could not rule out contamination of products made since the company first launched in March 2022. Stores nationwide pulled the product, which was advertised as having “next-to-breast milk benefits.”

Investigators with the U.S. Food and Drug Administration have yet to identify the root cause.

In a statement, the agency said it had identified 17 different strains of the illness-causing bacteria in samples from patients, finished cans of formula and ingredients. The samples “add to the available evidence needed to investigate the root cause of this outbreak,” but aren’t definitive, the agency said.

Previously, FDA officials indicated that powdered whole milk used to make ByHeart infant formula could be a source of contamination.

Illnesses caused by botulism bacteria in infant formula are rare, and the size and scope of the ByHeart outbreak is unprecedented, food safety experts said.

The disease occurs when babies ingest botulism spores that germinate in the intestine and produce a dangerous toxin that attacks the nervous system. Death rates were once as high as 90%, but now are less than 1% with treatment.

The only treatment for the disease is an IV medication, known as BabyBIG, made from the pooled blood plasma of adults who have been immunized against botulism. California’s program is the sole source worldwide.

ByHeart, which accounted for about 1% of the U.S. infant formula market, previously sold about 200,000 cans of the product per month. Parents of babies sickened in the outbreak said they chose the formula, which cost about $42 per can, because of its touted health benefits.

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.