Outpatient Infant Botulism in the United States, 1976-2021

Objective

To characterize cases of outpatients with infant botulism (IB) in the US identified by the Infant Botulism Treatment and Prevention Program at the California Department of Public Health from 1976 through 2021.

Study design

Outpatient IB cases were defined as patients presenting with an illness consistent with the known paralyzing action of botulinum neurotoxin and with laboratory confirmation. Outpatient cases were distinguished from the majority of patients with IB by the atypical fact that they did not require hospitalization throughout the course of their illness.

Results

Of the 4372 cases of IB identified by the Infant Botulism Treatment and Prevention Program over a 45-year period (1976-2021), 17 (0.4%) were outpatient cases. Most (11/17; 65%) cases occurred in California. The median age at disease onset was 20 weeks (range = 6 to 55 weeks). The most common symptom among cases was constipation (16/17; 94%). Most patients (16/17; 94%) had at least one cranial nerve palsy, manifested as decreased head control, ptosis, weak cry, or poor suck.

Conclusions

Outpatient IB occurs nationwide, although clinical diagnosis may be difficult because the severity of symptoms do not necessitate hospitalization or more comprehensive clinical intervention. Identification of outpatient cases requires an astute clinician and a capable, willing diagnostic testing laboratory. It is likely that more outpatient cases of IB are occurring than are presently recognized in infants mildly affected by this disease. Healthcare providers should consider the possibility of IB when presented with a previously well infant with failure to thrive, poor feeding, constipation, mild hypotonia, or cranial nerve palsy.