As health officials investigate more than 30 cases of infant botulism linked to ByHeart baby formula since August, parents who say their children were sickened with the same illness months before the current outbreak are demanding answers, too.
California public health officials confirmed late Friday that six babies in that state who consumed ByHeart formula were treated for botulism between November 2024 and June 2025, up to nine months before the outbreak that has sickened at least 31 babies in 15 states.
At the time, there was “not enough evidence to immediately suspect a common source,” the California Department of Public Health said in a statement.
Even now, “we cannot connect any pre-August 1 cases to the current outbreak,” officials said.
Parents of at least five babies said that their infants were treated for the rare and potentially deadly disease after drinking ByHeart formula in late 2024 and early 2025, according to reports shared with The Associated Press by Bill Marler, a Seattle food safety lawyer representing the families.
Amy Mazziotti, 43, of Burbank, California, said her then-5-month-old son, Hank, fell ill and was treated for botulism in March, weeks after he began drinking bottles filled with ByHeart formula.
Katie Connolly, 37, of Lafayette, California, said her daughter, M.C., then 8 months old, was hospitalized in April and treated for botulism after being fed ByHeart formula in hopes of helping the baby sleep.
For months, neither mother had any idea where the infections could have originated. Such illnesses in babies typically are caused by spores spread in the environment or by contaminated honey.
Then ByHeart recalled all of its products nationwide on Nov. 11 in connection with growing cases of infant botulism.
As soon as she heard it was ByHeart, Mazziotti said she thought: “This cannot be a coincidence.”
ByHeart officials this week confirmed that laboratory tests of previously unopened formula found that some samples were contaminated with the type of bacteria that leads to infant botulism.
Marler said at least three other cases that predate the outbreak involved babies who drank ByHeart and were treated for botulism, according to their families. One consumed ByHeart formula in December 2024. The other two were sickened later in the spring, he said.
An official with the U.S. Centers for Disease Control and Prevention