Association between Weather Variables and Viral Gastroenteritis in the United States.

Infectious gastroenteritis (IGE) is a major cause of pediatric morbidity globally, with viral pathogens accounting for a substantial proportion of cases. While seasonal patterns of viral IGE are well recognized, the association between specific environmental exposures, such as ambient temperature, and viral IGE has not been fully quantified. First, we performed a secondary analysis of data from a prospective, multisite study of children presenting to emergency departments at five medical centers across the continental United States, linking individual level laboratory data to environmental exposures, including temperature, humidity, and air pollutants, measured during the 14 days preceding symptom onset. Mixed-effects logistic regression was applied to evaluate the association between viral IGE and environmental exposures, adjusting for site-level clustering and patient age. Among 868 children with IGE, higher ambient temperature was inversely associated with viral etiology (OR 0.50, 95% CI 0.36-0.68, p < 0.001). We did not find statistically significant associations between other environmental variables and viral IGE. Then, to contextualize these individual-level findings in children, we examined all-ages population-level surveillance data from GermWatch, a regional laboratory testing-based infectious disease surveillance system, which demonstrated concordant declines in viral pathogen detection with increasing temperature. These findings support the association of weather with viral transmission patterns. Incorporating environmental context into clinical decision-making may improve diagnostic stewardship and support more effective resource allocation during periods of increased viral IGE prevalence.