In an email, an FDA spokesperson said it’s too soon to draw conclusions about any specific ingredient, manufacturing process or other contributing factor in the Nara investigation.

Both companies said they are cooperating with health officials.

ByHeart and Nara Organics products account for a small fraction, about 1%, of the U.S. formula market, according to the FDA. Infant nutrition experts said the country’s supply is overwhelmingly safe.

“I don’t want families to think that this is something we expect to see in all powder formulas,” Dr. Sharon Nachman, chief of pediatric infectious diseases at Stony Brook Children’s Hospital in New York, said. “But to have two outbreaks come so close to each other with the same pathogen is quite worrisome.”

Monthslong recoveries

A yet-to-be-published report from the Centers for Disease Control and Prevention illustrates the severity of infant botulism, even after babies are released from the hospital. Recovery can be extremely slow, as it involves the regeneration of the signaling pathway between nerves and muscles, a process that can take months.

Myra Brooks, an epidemic service intelligence officer with the CDC, reviewed medical records for 46 of the 48 babies in the ByHeart outbreak. None of the children had a fever that would indicate a different cause for their illness, like a virus. Other symptoms were key.

Of the 46 babies:

• 91% had problems with their sucking reflex
• 87% were constipated
• 76% couldn’t hold their heads up
• 24% had trouble breathing

More than half of the babies, 61%, needed extra oxygen to help them breathe or be fed through tubes in their noses. Eleven percent had to be intubated or have a feeding tube surgically placed in their stomachs.

Two-thirds of the infants needed special therapy to retrain their mouths to eat, Brooks said. Her findings are expected to be published in one of the CDC’s upcoming Morbidity and Mortality Weekly Reports.

For Brooks, the results of the CDC report were reassuring. “Most infants make a complete recovery from this disease,” she said.

A rapid decline

It’s been more than a year since Hank Mazziotti, now just shy of age 2, was hospitalized with infant botulism. He still can’t move his bowels without the aid of laxatives, his mother, Amy, said.

“It’s so painful for him that he’s throwing up and pooping at the same time,” she said. “That’s a weekly thing.”

Amy Mazziotti said she bought a can of ByHeart in mid-February 2025 because she needed to supplement her breast milk supply. The formula was advertised as being made in small batches and the closest thing to breast milk. “They had good marketing, to be honest,” she said.

Hank’s constipation began within days. By early March, the 6-month-old — who’d just discovered how to roll over and was doing so nonstop — stopped performing his new trick. He barely drank from his bottle. His head flopped to one side.

“His condition declined rapidly,” Mazziotti said. “He couldn’t move. He couldn’t even cry. His whole face was just paralyzed.”

The search for answers

Tests conducted by the FDA found Clostridium botulinum in ByHeart formula as well as in a powdered milk ingredient that came from ByHeart’s milk supplier, Dairy Farmers of America, a cooperative based in Kansas City, Kansas. The agency hasn’t determined how the bacteria got in the ByHeart samples but is continuing to investigate factors related to ingredients, methods of processing and production environments, according to a spokesperson.

After the ByHeart recall, the company gave its customers a discount code for Nara Organics, a ByHeart spokesperson said in an email, to help families transition to a similar product. The companies are separate “with no corporate, financial, contractual, operational, or manufacturing relationship,” the spokesperson wrote.

A spokesperson from Nara Organics referred to an Instagram post from last week by company founder Esther Hallam, who reaffirmed that none of the products had tested positive for Clostridium botulinum and that the company voluntarily recalled its products “out of an abundance of caution.”

The post also touted Nara Organics’ use of a type of testing, called SRC, that can detect bacteria, but not necessarily Clostridium botulinum. It’s not required by the FDA.

“Families often have a confused idea that formulas that are organic, that are more expensive, that advertise on social media, are somehow safer than other formulas,” Dr. Steven Abrams, a neonatologist and professor of pediatrics at the University of Texas at Austin, said.

“There’s no evidence for that,” he said. “All formulas go through the same safety processes.”

The formula recalls occurred several months after the Department of Health and Human Services, under the direction of Robert F. Kennedy Jr., announced “Operation Stork Speed,” a program intended to review the safety of ingredients in infant formula and focus on testing for heavy metals and other contaminants.

“While infant botulism associated with infant formula remains extremely rare, every case is one too many,” Emily Hilliard, an HHS spokeswoman, said in an email. “That is why the FDA is expanding testing, strengthening surveillance, and accelerating scientific work through Operation Stork Speed to better understand risks and further strengthen safeguards across the infant formula supply chain.”

Northeastern University’s Detwiler said he’d like to see more of an emphasis on prevention and increased surveillance of infant formula before, not after outbreaks occur.

“When the same rare illness appears twice within months, involving products intended for infants, the question is no longer whether this can happen,” Detwiler said. “The question is whether we will finally learn enough from the warning signs to stop the next child from becoming the next statistic.”