OBJECTIVE. This study describes the burden and epidemiologic features of infectious disease hospitalizations among infants in the United States.

METHODS. Hospitalizations with an infectious disease listed as a primary diagnosis for infants (<1 year of age) in the United States during 2003 were examined by using the Kids' Inpatient Database. National estimates of infectious disease hospitalizations, hospitalization rates, and various hospital parameters were examined.

RESULTS. During 2003, an estimated 286739 infectious disease hospitalizations occurred among infants in the United States and accounted for 42.8% of all infant hospitalizations. The national infectious disease hospitalization rate was 7010.8 hospitalizations per 100000 live births, or ∼1 infectious disease hospitalization for every 14 infants. The median length of stay was 3 days, and stays totaled >1 million hospital days for infants. Infectious disease hospitalization rates were highest among boys and nonwhite infants. The most commonly listed diagnoses among the infant infectious disease hospitalizations included lower respiratory tract infections (59.0%), kidney, urinary tract, and bladder infections (7.6%), upper respiratory tract infections (6.5%), and septicemia (6.5%). The median cost of an infectious disease hospitalization was $2235, with total annual hospital costs of approximately$690 million, among infants in the United States.

CONCLUSIONS. Infectious disease hospitalizations among infants account for substantial health care expenditures and hospital time in the United States, with respiratory disease hospitalizations constituting more than one half of all hospitalizations. Younger infants, boys, and nonwhite infants were at increased risk for infectious disease hospitalization. Measures to reduce racial disparities and the occurrence of respiratory tract infections should substantially decrease the infectious disease burden among infants.