By Philip R. Fischer, MD, FIDSA

Synopsis: As of early December 2025, a commercially prepared infant formula distributed throughout the United States was linked to 39 cases of life-threatening infant botulism in 18 states.

Source: Centers for Disease Control and Prevention. Investigation update: Infant botulism outbreak, November 2025. https://www.cdc.gov/botulism/outbreaks-investigations/infant-formula-nov-2025/investigation.html

On Nov. 8, 2025, the Centers for Disease Control and Prevention (CDC) reported a 10-state outbreak of infant botulism related to contaminated infant formula. At that time, a total of 13 infants were diagnosed with proven or suspected infant botulism in 10 states — Arizona, California, Illinois, Minnesota, New Jersey, Oregon, Pennsylvania, Rhode Island, Texas, and Washington. Epidemiologic investigation revealed that each affected child had consumed a particular product during the month prior to becoming ill, ByHeart Whole Nutrition infant formula.

In retrospect, three infants had become ill with botulism in August, another three in September, and 10 in October. Despite CDC warnings in early November, a generalized recall of all ByHeart Whole Nutrition infant formula on November 11, and news media coverage, the outbreak spread. There were totals of 23 cases by November 14, and 31 cases by November 21. As of Dec. 3, 2025, there had been 39 cases in 18 states. All children reported to be affected were hospitalized, and no deaths were documented.

In addition to the 10 states initially reported, cases have subsequently been identified in infant residents of Idaho, Kentucky, Massachusetts, Maine, Michigan, North Carolina, Virginia, and Wisconsin. Reporting eight cases, Texas accounts for more than other states.

The ByHeart company accounts for just 1% of infant formula produced and used in the United States, but its formula also is distributed internationally. Initially, the two implicated lots of formula were recalled voluntarily, but the company subsequently recalled all their infant formula. The investigation is ongoing.

Commentary

During the first year of life, babies are susceptible to illness caused by toxin released by spores of Clostridium botulinum. The botulinum neurotoxin (also called “botulism toxin”) binds to neuron receptors to block acetylcholine release into neuromuscular synapses and can cause gastrointestinal dysmotility (with constipation) and progressive paralysis (droopy eyelids, difficulty swallowing, descending hypotonia with limb weakness, and respiratory insufficiency).¹ Treatment with botulism immune globulin (BabyBIG, obtained from the California Department of Health) should be initiated as soon as botulism is clinically suspected, even before results of stool testing (available with guidance from state health departments) are available.

Sepsis can be in the differential diagnosis of young infants presenting with botulism, and presumptive antibiotics sometimes are given while blood culture results are pending. Gentamicin often is used for young infants with possible sepsis but should be avoided in situations of possible botulism since gentamicin is synergistic with botulinum toxin at the neuromuscular junction and can exacerbate paralysis.²

The current outbreak of infant botulism is especially concerning since the source of the toxin-releasing infection was from a commercial product. Infant botulism more commonly comes from raw honey or from environmental sources (dust or dirt released from the soil at construction sites).³ A recent case of infant botulism in the United Kingdom was linked to commercially prepared raw/roasted peanut butter.⁴

Infant formula generally is very safe. However, a tragic situation in Israel in 2003 involved the inadvertent preparation of thiamine-deficient soy formula; of hundreds of children exposed to the inadequate formula, three died and 20 had severe neurodevelopmental consequences of beriberi.⁵ More commonly, infant formula, when prepared with unhygienic water, can cause diarrheal diseases; this still is a problem, especially in low-income countries such as Mozambique.⁶ Obviously, infant formula prepared commercially, and in homes, should incorporate clean water and supplies.

Philip R. Fischer, MD, DTM&H, is Professor of Pediatrics, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN.

References

1. Kobaidze K, Wiley Z. Botulism in the 21st century: A scoping review. Brown J Hosp Med. 2023;2(2):72707.

2. Santos JI, Swensen P, Glasgow LA. Potentiation of Clostridium botulinum toxin aminoglycoside antibiotics: Clinical and laboratory observations. Pediatrics. 1981;68(1):50-54.

3. Van Horn NL, Shah M. Infantile Botulism. 2025; Apr 6. In: StatPearls [Internet]. StatPearls Publishing; 2025 Jan–.

4. Crane RJ, Amar CF, Omoruyi H, et al. Peanut butter confirmed as the source in a case of infant botulism, United Kingdom, 2024. Euro Surveill. 2025;30(30):2500512.

5. Mimouni-Bloch A, Goldberg-Stern H, Strausberg R, et al. Thiamine deficiency in infancy: Long-term follow-up. Pediatr Neurol. 2014;51(3):311-316.

6. Faife S, Macuamule C, Gichure J, et al. Diarrhoeagenic Escherichia coli and Salmonella spp. contamination of food and water consumed by children with diarrhoea in Maputo, Mozambique. Int J Environ Res Public Health. 2024;21(9):1122.