What are the odds of an infant developing botulism from contaminated powdered infant formula?
Evidence quality 4.25/5
Eight-dimension review score against the quality rubric . Each dimension scored 1–5.
- D1 Source grounding
- 5/5
- D2 Source authority
- 5/5
- D3 Arithmetic
- 4/5
- D4 Uncertainty
- 3/5
- D5 Scope
- 4/5
- D6 Prose
- 4/5
- D7 Perception honesty
- 4/5
- D8 Caveat completeness
- 5/5
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No probability can be assigned to an infant getting botulism specifically from contaminated powdered formula, because the event has happened exactly once. Before November 2025 there had never been a formula-linked infant botulism outbreak recorded in the United States. The ByHeart outbreak that year closed with 48 cases across 17 states, all 48 hospitalized and treated with the antitoxin BabyBIG, and no deaths. Clostridium botulinum was found in ByHeart formula, and the company recalled every product on November 11, 2025. That is a single point-source contamination episode, now ended. It is not a recurring annual hazard with a stable rate, and treating it as one would mean inventing a denominator that does not exist.
The temptation is to divide the 48 cases by the roughly 3.6 million infants born in the US each year and report something like 1 in 75,000. That arithmetic is wrong in kind, not just in precision: it takes a one-time, non-stationary event and presents it as a steady-state probability for any given formula-fed infant. The honest statement is that the formula-attributable rate was approximately zero for the entire history of US surveillance until a single outbreak, and the long-run rate going forward is unknown and depends on manufacturing controls rather than on anything a population denominator can capture.
What does have a number is infant botulism overall, from all sources, and it is worth separating from the question. The CDC counts roughly 150 to 180 infant botulism cases nationally each year, with 152 confirmed in 2019. Against annual births that lands somewhere between about 1 in 24,000 and 1 in 53,000 infants in the first year of life, the spread reflecting a genuine two-fold disagreement between CDC surveillance counts and the lower published incidence of 1.9 per 100,000. The great majority of those cases trace to environmental spore exposure, soil and household dust, with a minority linked to honey, and in most infants the source is never identified at all. Formula was not on that list before 2025, and the 2025 outbreak was an addition of one contained event, not the emergence of a rate.
Related tidbits
Before 2025 there had never been a formula-linked infant botulism outbreak in the US, so there is no defensible long-run per-infant rate to cite. The 2025 ByHeart episode was a single point-source contamination, now closed, not a recurring hazard of formula feeding.
Claim ledger
Every number below is what each source reported, with the verbatim quote we relied on and how we arrived at our figure. Click any link to verify directly.
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[1] U.S. Centers for Disease Control and Prevention (CDC) — Infant Botulism Outbreak Linked to Infant Formula, November 2025
Infant Botulism Outbreak Linked to Infant Formula, November 2025- Statistic
Final outbreak total: 28 confirmed + 20 probable = 48 cases across 17 states; 48 hospitalizations; 0 deaths. ByHeart recalled all infant formula products on November 11, 2025. Investigation status: Closed.- Excerpt
“The outbreak included 28 confirmed cases and 20 probable cases. Hospitalizations: 48. States: 17. Deaths: 0. On November 11, 2025, ByHeart recalled all infant formula products. This outbreak is over.”
- Source data from
- 2026-03-05
- Accessed
- 2026-06-13
- Calculation
- Final CDC investigation figures (48 cases / 17 states), which superseded the interim Dec 10, 2025 press-release count of 51/19. These are outbreak case counts, not a rate: there is no denominator of exposed formula-fed infants, so this cannot be converted to a per-infant probability. Used to establish that the event was a single point-source contamination episode that has been closed, not a recurring hazard.
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[2] U.S. Centers for Disease Control and Prevention (CDC) — CDC's Rapid Response Helps Solve First Infant Botulism Outbreak Linked to Formula
CDC's Rapid Response Helps Solve First Infant Botulism Outbreak Linked to Formula- Statistic
First-ever outbreak of infant botulism linked to formula; CDC typically expects 150-180 individual infant botulism cases annually (from all sources combined).- Excerpt
“While we typically expect to see 150-180 individual cases of infant botulism annually, an outbreak of infant botulism is unprecedented.”
- Source data from
- 2025-12-10
- Accessed
- 2026-06-13
- Calculation
- Establishes two load-bearing facts: (1) this was the first formula-linked infant botulism outbreak ever recorded in the US, meaning the historical formula-attributable rate is approximately zero; (2) the all-cause baseline runs 150-180 infant botulism cases per year, the great majority of which are honey/environmental, not formula. The interim 51/19 figure in this release was later revised to 48/17 by the closed investigation page. Cited for the 'first ever' framing and the all-cause baseline, not for the case count.
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[3] StatPearls / NCBI Bookshelf — Infantile Botulism (StatPearls)
Infantile Botulism (StatPearls)- Statistic
US infant botulism incidence ~1.9 per 100,000 live births (~77 cases/yr); in the majority of affected infants the source of C. botulinum spores is never identified; honey accounts for a minority of cases.- Excerpt
“In the United States, the incidence is 1.9 per 100,000 live births, resulting in around 77 new cases each year.”
- Source data from
- 2023-08-08
- Accessed
- 2026-06-13
- Calculation
- All-cause infant botulism baseline. 1.9/100,000 live births = 0.000019 per infant over the first year. This is the headline-adjacent context figure, NOT the formula-attributable rate the question asks about. Note the ~2x conflict with CDC surveillance: 152 infant cases in 2019 against 3.67M births that year is ~4.2/100,000 (~1 in 24,000), and the CDC press release cites 150-180/yr; StatPearls' 77/yr sits at the low end. Surfaced in prose rather than averaged.
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[4] U.S. Centers for Disease Control and Prevention (CDC) — National Botulism Surveillance Summary, 2019
National Botulism Surveillance Summary, 2019- Statistic
In 2019, 152 laboratory-confirmed infant botulism cases were reported to CDC out of 215 total botulism cases.- Excerpt
“Health departments reported 152 cases of infant botulism, all of which were laboratory-confirmed.”
- Source data from
- 2021-01-01
- Accessed
- 2026-06-13
- Calculation
- Independent CDC surveillance count corroborating the all-cause baseline order of magnitude. 152 infant cases / 3,622,673 US births (2024 figure used as a stable recent denominator) approximates 4.2 per 100,000, i.e. roughly 1 in 24,000 infants in their first year from all sources combined. None of these 2019 cases were formula-linked (the first formula outbreak was 2025). Used to bracket the all-cause baseline against the lower StatPearls figure.
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[5] CDC / National Center for Health Statistics (NCHS) — U.S. Births Increase by 1% in 2024
U.S. Births Increase by 1% in 2024See all 2 Likelier entries citing this source →
- Statistic
Provisional total US births in 2024: 3,622,673.- Excerpt
“the number of births increased by 1% from 2023, with 3,622,673 births recorded in 2024.”
- Source data from
- 2025-04-23
- Accessed
- 2026-06-13
- Calculation
- Supplies the annual live-birth denominator used to convert CDC infant botulism case counts into an all-cause per-infant baseline rate (e.g. 152/3,622,673 ~ 4.2 per 100,000). Used only for the context baseline; the formula-attributable rate has no defensible denominator and is left as no_reliable_estimate.