California health officials say the current infant botulism outbreak traced to ByHeart formula was preceded by several cases beginning in November 2024. To date more than 100 infants have received treatment for botulism poisoning.
The California Department of Public Health (CDPH) is reporting that at least six cases of infant botulism were detected between November 2024 and March 2025. Until the announcement the current outbreak was thought to have begun in August this year.
Currently there are 31 confirmed patients from 15 states. All of the babies have required hospitalization but none have died. Spores that cause botulism poisoning have been found in unopened containers of ByHeart infant formula. All of the sick infants were fed the formula, according to the U.S. Centers for Disease Control and Prevention.
“CDPH is continuing investigate, but at this time we cannot connect any pre-Aug. 1 cases to the current outbreak,” a CDPH spokesperson said.
The spokesperson explained that in early 2025 there was not enough evidence to immediately suspect a common source among the six suspected cases, and that the number of cases were within expected case numbers based on previous years’ trends.
Prior to the current outbreak, no powdered infant formula had tested positive for C botulinim in the United States. The CDPH said that, from Aug. 1 through Nov. 19, 107 infants nationwide have received treatment with BabyBIG, a human plasma-derived treatment for infants with botulism. That includes confirmed cases and infants who were being treated while awaiting test results.
The CDPH developed and is the only source of BabyBIG. The CDC and Food and Drug Administration began their investigation into the outbreak after officials with CDPH’s Infant Botulism Treatment and Prevention Program alerted them to an increase in requests for the treatment.
ByHeart initially recalled two lots of its powdered infant formula. As the outbreak investigation progressed the company recalled all of its infant formula. The FDA is warning parents and caregivers that some of the recalled formula is still on store shelves.
The infant formula has been sold in other countries and several of them have issued alerts.
Symptoms of infant botulism poisoning include constipation, poor feeding, loss of head control, and difficulty swallowing, which can progress to difficulty breathing and respiratory arrest. Symptoms of infant botulism, which is diagnosed clinically, can take as long as several weeks to develop following formula ingestion.