Federal health authorities on Wednesday expanded the investigation of an infant botulism outbreak linked to recalled ByHeart baby formula, now including all illnesses reported since the company began producing formula in March 2022. The U.S. Food and Drug Administration said it “cannot rule out the possibility that contamination might have affected all ByHeart formula products” ever manufactured.
The outbreak currently involves at least 51 infants across 19 states. The Centers for Disease Control and Prevention updated the case definition to include “any infant with botulism who was exposed to ByHeart formula at any time since the product’s release.” The most recent reported illness occurred on Dec. 1. No deaths have been reported. The outbreak was first announced on Nov. 8 and initially involved 39 suspected or confirmed cases since August 2025, prompting the company to recall all its products on Nov. 11. ByHeart, a New York-based organic formula manufacturer founded in 2016, accounts for roughly 1% of the U.S. formula market, selling about 200,000 cans monthly.
Families affected by the outbreak expressed relief at the expanded investigation. Andi Galindo of Redondo Beach, California, whose 5-week-old daughter was hospitalized with botulism after drinking ByHeart, said the news highlights the need for accountability regarding the company’s manufacturing practices. Another parent, Amy Mazziotti of Burbank, California, said her son’s inclusion in the outbreak investigation brings “relief, gratitude and hope that the truth is finally being recognized.” ByHeart officials said they are cooperating with federal authorities to understand the full scope of related cases, noting that new data will help guide their investigation into the root cause of contamination.
Laboratory tests have found contamination in multiple lots. Independent testing of 36 samples from three different production lots revealed the bacteria that can cause infant botulism. CDC scientists said contamination appears to have persisted across multiple production runs and lots, preventing officials from isolating the problem to a specific batch. Previous inspections of ByHeart plants in Iowa, Oregon, and Pennsylvania found multiple issues, including mold, water leaks, insects, and prior bacterial contamination with Cronobacter sakazakii. In 2023, the FDA issued a warning letter detailing areas needing corrective action.
Infant botulism is rare, affecting fewer than 200 babies annually in the U.S. It occurs when spores of botulism bacteria germinate in a baby’s intestines and release toxins that attack the nervous system. Infants under one year are particularly vulnerable due to immature gut microbiomes. Symptoms can take up to 30 days to appear and include poor feeding, constipation, drooping eyelids, floppy muscles, and difficulty swallowing or breathing. The only treatment is BabyBIG, an IV medication derived from the blood plasma of adults immunized against botulism.
Several families have filed federal lawsuits against ByHeart, alleging negligence and defective formula. They are seeking compensation for medical expenses, emotional distress, and other damages resulting from the illnesses. Health officials continue to warn that families should avoid using any recalled ByHeart products.