Potential Cause of ByHeart Infant Botulism Outbreak May Be Whole Milk Ingredient

The outbreak has infected 51 babies across the United States, with all of them getting hospitalized.

A container of ByHeart baby formula, which was recently recalled by ByHeart, in Flagstaff, Ariz., on Wednesday, Nov. 12, 2025. AP Photo/Cheyanne Mumphrey

A multistate outbreak of botulism linked to infant formula products sold by New York-based ByHeart could have originated from whole milk powder used in the product, according to a Jan. 23 statement from the Centers for Disease Control and Prevention.

On Nov. 11, ByHeart announced the recall of all batches of ByHeart Whole Nutrition Infant Formula cans and Anywhere Pack due to contamination from Clostridium botulinum, a bacterium that can cause life-threatening illness or death.

As part of the Food and Drug Administration testing, two samples collected by the agency have tested positive for botulinum.

One is a ByHeart powdered infant formula closed product sample that matches a clinical isolate from an infant included in this outbreak, while the second sample was whole milk powder collected by the FDA at a ByHeart supplier.

“Clostridium botulinum found in the sample of whole milk powder is a genetic match to the Clostridium botulinum detected in the finished product sample of ByHeart’s infant formula, according to analysis conducted by ByHeart,” the CDC statement said.

The FDA investigation is ongoing to identify the source of contamination.

According to Dec. 10 data from the CDC, there have been 51 suspected or confirmed infant botulism infections across 19 states in the country. All were hospitalized and treated. No deaths were reported. There have been no new cases since then.

“On December 23, 2025, ByHeart publicly reported positive test results for Clostridium botulinum in six of 36 samples of finished product. These six samples were taken from two batches (batch 251261P2 and batch 251131P2), which were both included in the initial product recall,” CDC said.

The agency said additional tests were being conducted.

“Sample analysis is ongoing, and additional results will be reported as they become available. The detection of Clostridium botulinum in infant formula, or its ingredients, is complex, and confirmation of results can take several weeks,” the agency added.

ByHeart said it has been cooperating with the FDA and other agencies since Nov. 7 to investigate bacterial contamination of its formula products, as noted in a Jan. 23 update.

“While the FDA’s investigation is ongoing, these new findings about the whole milk powder that we source suggests that we are significantly closer to determining the root cause of the contamination of ByHeart formula,” the company said.

“We take our responsibility to ByHeart families incredibly seriously, and we are deeply sorry for the impact this outbreak has had on our community.”

According to ByHeart, the company is working with its lab-testing partner on new testing protocols for botulinum toxin from farms to factories. The company is evaluating a comprehensive set of additional preventive controls across the supply chain and manufacturing process, it said.

Children at Risk

In an update on Jan. 23, the FDA said this was the first documented botulism outbreak in the United States linked to contaminated infant formula.

Most infants with botulism initially develop symptoms such as constipation, poor feeding, difficulty swallowing, and loss of head control, the FDA said. Eventually, breathing difficulties and respiratory arrest may surface. Symptoms can take as long as several weeks to show up after ingesting the contaminated infant formula.

The FDA asked parents and caregivers to stop using the recalled products “immediately.”

If a child consumed ByHeart formula and is experiencing symptoms, “seek immediate medical attention,” the agency said.

“If your child consumed ByHeart formula and is not currently showing symptoms, continue monitoring them and seek medical attention if symptoms develop.”

According to the FDA, ByHeart infant formula products account for about 1 percent of all infant formula sold in the country. The outbreak is not expected to create infant formula shortages.

Out of the 19 states where infant botulism has been detected in the current outbreak, California and Texas are the most affected, followed by Minnesota and Oregon.

According to an April 2024 report from the CDC, infant botulism is triggered after spores of the botulinum bacteria are swallowed. These spores temporarily colonize a child’s large intestine, producing a neurotoxin that negatively impacts the baby.

Once clinical determination of infant botulism is made, the infant must be treated with BabyBIG, an antitoxin, as soon as the medication is available.

“Keep in mind, initial diagnosis is based on clinical symptoms. Do not wait for laboratory confirmation to begin treatment,” CDC said.