Contaminated ByHeart baby formula has now made at least 15 infants across 12 states sick, health officials confirmed Monday. The outbreak, which began spreading in mid-August, jumped from the 13 cases reported just two days earlier.
According to the health officer for the California Department of Public Health, Dr. Erica Pan, nine cases have been definitively confirmed as infant botulism type A. Six additional suspected cases are still awaiting lab confirmation. So far, no babies have died but all of the affected infants have required hospitalization.
Investigators confirmed the presence of dangerous bacteria Clostridium botulinum in the formula after testing an opened can that had been fed to one of the sick babies. The sample tested positive for the pathogen. In lab tests, when researchers exposed mice to the bacteria, the animals quickly became ill, Dr. Pan said.
The company has asked officials to test unopened cans from the recalled batches to determine the extent of the problem.
Federal officials have confirmed that at least 84 babies across the United States have been treated for botulism since August. This number includes the confirmed ByHeart cases as well as other suspected infections. The FDA is currently investigating whether any of these other cases might also be connected to contaminated formula.
Infant botulism is a rare but serious condition that typically affects fewer than 200 babies each year in America. The illness develops when bacteria produce a toxin inside an infant's intestines. The hardy spores that cause this bacteria are found naturally in the environment—in dust, dirt, and water—and can also be found in honey.
Babies under one year old are especially vulnerable because their digestive systems aren't mature enough to stop the spores from sprouting and creating toxins. The illness can take weeks to develop after a baby is exposed. Early warning signs include constipation, poor feeding, weak head control, drooping eyelids, and a loss of facial expression. In severe cases, babies may have trouble swallowing or breathing.
Dr. Steven Abrams, a nutrition expert at the University of Texas, said this is the first time a powdered infant formula outbreak of this kind has been documented. "This would be extremely rare," he said.
There is only one treatment available for infant botulism: a medication called BabyBIG, which is given intravenously. The treatment is made from blood plasma taken from adults who have been vaccinated against botulism. California's Infant Botulism Treatment and Prevention Program developed it and is the only source in the world.
BabyBIG can shorten hospital stays and reduce how severe the illness becomes. Every child affected by the ByHeart outbreak has received this treatment, the CDC confirmed. Each single vial of the treatment costs $69,300.
Because botulism can damage a baby's ability to breathe, many infants who develop breathing difficulties may also need to be placed on ventilators to help them survive.
ByHeart, which started in 2016, sells less than 1 percent of all infant formula in the United States, according to the CDC. The company sells its products online and through major retailers nationwide.
ByHeart has also faced quality issues before. In 2022, the company recalled five batches of formula after testing found contamination at its packaging plant. In 2023, the FDA sent a warning letter to ByHeart pointing out "areas that still require corrective actions."
The federal government is now taking a closer look at all baby formula ingredients.
Health Secretary Robert F. Kennedy Jr. has ordered the FDA to review what goes into infant formula as part of an effort called "Operation Stork Speed." This is the first time since 1998 that officials have done a thorough examination of formula ingredients in light of updates in nutrition research.