The FDA and CDC, in collaboration with the California Department of Public Health (CDPH), Infant Botulism Treatment and Prevention Program (IBTPP), and other state and local partners, continue to investigate a multistate outbreak of infant botulism. Epidemiologic and laboratory analyses indicate that ByHeart Whole Nutrition infant formula is the source of this multistate outbreak of infant botulism. No new cases have been added to the investigation since December 10, 2025. Product sampling and testing is being conducted by FDA, CDC, state partners, and ByHeart. Additionally, FDA collected ByHeart ingredient samples for analysis, as part of the investigation. As of January 23, 2026, two samples collected by FDA tested positive for Clostridium botulinum (toxin), Type A. One is a ByHeart powdered infant formula closed product sample that matches a clinical isolate from an infant included in this outbreak according to whole genome sequencing (WGS) analysis. These sam...