FILE - The Food and Drug Administration seal is seen at the Hubert Humphrey Building Auditorium in Washington, April 22, 2025. (AP Photo/Jose Luis Magana, File)

Preliminary tests showed that ByHeart baby formula contained the type of bacteria that produces the toxin linked to a botulism outbreak, California health officials said.

The outbreak has sickened at least 13 infants in 10 states. No deaths have been reported.

“Consumers in possession of this product should stop using it immediately,” the California Department of Public Health said in a statement late Saturday.

More tests of ByHeart Whole Nutrition Infant Formula are pending as state and federal health officials investigate the outbreak that started in mid-August. The New York-based company this weekend recalled two lots of the powdered product.

Here’s what to know about the outbreak and infant botulism.

Infant botulism outbreak

The outbreak of infant botulism has sickened babies aged 2 weeks to 5 months since mid-August. All were hospitalized after consuming ByHeart powdered formula, according to the U.S. Centers for Disease Control and Prevention.

The cases occurred in Arizona, California, Illinois, Minnesota, New Jersey, Oregon, Pennsylvania, Rhode Island, Texas and Washington.

ByHeart officials agreed to recall two lots of the company’s Whole Nutrition Infant Formula, according to the U.S. Food and Drug Administration. The formula has a best-by date of December 2026.

California health officials tested a can of the powdered formula that was fed to a baby who fell ill. The results “suggest the presence” of the type of bacteria that produces the botulism toxin confirmed in other cases. It can take several days to confirm the results.

ByHeart officials said that “more testing is needed” to know whether the type of bacteria that causes botulism is present. It comes from a large family of bacteria, many of which are found naturally in the environment and don’t cause illness, the company said.

“We take this very seriously,” it said in a statement Sunday.

The FDA is investigating reports of 83 cases of infant botulism reported since August including the cases linked to Byheart baby formula.

Causes of infant botulism

Infant botulism typically affects fewer than 200 babies in the U.S. each year. It is caused by a type of bacteria that produces toxins in the large intestine. The bacterium is spread through hardy spores present in the environment that can cause serious illness, including paralysis.

Infants younger than 1 are particularly vulnerable and can be sickened after exposure to the spores in dust, dirt or water or by eating contaminated honey.

Symptoms can take weeks to develop and can include poor feeding, loss of head control, drooping eyelids and a flat facial expression. Babies may feel “floppy” and can have problems swallowing or breathing.

No known outbreaks of infant botulism tied to powdered formula have previously been confirmed, said Dr. Steven Abrams, a University of Texas nutrition expert.

“This would be extremely rare,” he said.

**Infant botulism treatment **

The only treatment is known as BabyBIG, an IV medication made from the pooled blood plasma of adults immunized against botulism. California’s Infant Botulism Treatment and Prevention Program developed the product and is the sole source worldwide.

BabyBIG works to shorten hospital stays and decrease the severity of illness in babies with botulism. Because the infection can affect the ability to breathe, infants often need to be placed on ventilators.

All of the children in the ByHeart outbreak have received the medication, the CDC said.

**Potential impact on U.S. formula supplies **

There is no danger of infant formula shortages because of this outbreak. ByHeart, which was founded in 2016, accounts for an estimated 1% of national formula sales, according to the CDC. The company sells formula through its website and in retail stores nationwide.

That’s different that the crisis caused when formula produced by Abbott was linked to infant deaths and illnesses in 2022.

That product was contaminated with a different germ that can cause severe illness and death in babies. Because Abbott is one of the top manufacturers of infant formula in the U.S., the closure of its manufacturing plant in Michigan triggered massive shortages of formula across the U.S.

In 2022, ByHeart recalled five batches of infant formula after a sample at the company’s packaging plant tested positive for cronobacter sakazakii, the germ at the heart of the Abbott crisis. In 2023, the FDA sent a warning letter to the company detailing “areas that still require corrective actions.”

Reviewing infant formula ingredients

Federal health officials have vowed to overhaul the U.S. food supply and are taking a new look at infant formula.

Health Secretary Robert F. Kennedy Jr. has directed the Food and Drug Administration to review the nutrients and other ingredients in infant formula, which fills the bottles of millions of American babies.

The effort, dubbed “Operation Stork Speed,” is the first deep look at the ingredients since 1998.

FDA officials are reviewing comments from industry, health experts and public to decide next steps.

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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.