Federal health officials on Wednesday expanded an outbreak of infant botulism tied to recalled ByHeart baby formula to include all illnesses reported since the company began production in March 2022. The U.S. Food and Drug Administration said investigators “cannot rule out the possibility that contamination might have affected all ByHeart formula products” ever made. The outbreak now includes at least 51 infants in 19 states. The new case definition includes “any infant with botulism who was exposed to ByHeart formula at any time since the product’s release,” according to the U.S. Centers for Disease Control and Prevention. The most recent illness was reported on Dec. 1. No deaths have been reported in the outbreak, which was announced Nov. 8. Previously, health officials had said the outbreak included 39 suspected or confirmed cases of infant botulism reported in 18 states since August. That’s when officials at California’s Infant Botulism Treatment and Prevention Program reported a rise in treatment of infants who had consumed ByHeart formula. Another 12 cases were identified with the expanded definition, including two that occurred in the original timeline and 10 that occurred from December 2023 through July 2025. ByHeart, a New York-based manufacturer of organic infant formula founded in 2016, recalled all its products sold in the U.S. on Nov. 11. The company, which accounts for about 1% of the U.S. infant formula market, had been selling about 200,000 cans of the product each month.