A total of 37 infants have been hospitalized due to an outbreak of infant botulism, a serious illness caused by botulinum toxin, according to federal health officials. The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) reported that cases have now spread to 17 states, with the addition of two new states. This marks an increase of six cases from the previous total of 31 reported on November 20.

The outbreak includes states such as Arizona, California, Idaho, Illinois, Kentucky, Massachusetts, Maine, Michigan, Minnesota, North Carolina, New Jersey, Oregon, Pennsylvania, Rhode Island, Texas, Washington, and Wisconsin. The FDA noted that for the 36 cases with available onset information, symptoms began between August 9, 2025, and November 19, 2025. All 37 infants affected have been hospitalized, and no deaths have been reported.

Of the 35 infants for whom age and sex data is available, their ages range from 16 to 264 days, with 15 identified as female. The FDA indicated that all infants who fell ill had consumed various lots of ByHeart Whole Nutrition powdered infant formula. The agency is currently conducting laboratory confirmations for some cases.

The multistate outbreak investigation is being led by the FDA and CDC, in collaboration with the California Department of Public Health's Infant Botulism Treatment and Prevention Program and other local health authorities. The investigation aims to identify the source of contamination.

ByHeart initially announced a voluntary recall of two batches of its Whole Nutrition Infant Formula on November 8, following notification from the FDA about a broader investigation into the infant botulism outbreak. On November 11, the company expanded the recall to include all batches of its formula nationwide. In a November 19 update, ByHeart reported that testing revealed some samples of its formula contained the bacteria Clostridium botulinum, which can lead to botulism.

"We tested 36 samples from three lots and received positive test results for Clostridium botulinum Type A in five of the 36 samples across all three lots. Based on these results, we cannot rule out the risk that all ByHeart formula across all product lots may have been contaminated," the company stated. ByHeart has urged parents and caregivers to stop using the formula immediately and to monitor for symptoms of infant botulism.

Clostridium botulinum bacteria can produce a toxin that affects the nervous system, leading to severe symptoms such as difficulty breathing, muscle weakness, and paralysis. Infant botulism occurs when babies ingest spores of the bacteria, which can grow in their intestines and produce the toxin. The CDC advises that infants under 12 months, particularly those under 2 months, are at risk. Foods like honey, which may contain spores, should not be given to infants under one year of age.

Symptoms of infant botulism include poor feeding, constipation, slow-reacting pupils, drooping eyelids, reduced facial expressions, low muscle tone, and a weaker-than-normal cry. The CDC recommends seeking immediate medical attention if an infant has consumed ByHeart formula and exhibits any of these symptoms.

ByHeart has advised consumers to stop using the recalled formula and dispose of it. The company is also offering a full refund for all products purchased on its website since August 1, 2025. Parents can contact ByHeart at 866-201-9069 for refund instructions. This article has been updated to reflect the latest information from the CDC and FDA regarding the infant botulism outbreak.