Work

Seasonality of medically attended norovirus gastroenteritis and its association with climatic factors within an US integrated healthcare system, 2016–2019

Year: 2025

Type: article

Abstract: BACKGROUND: While acute gastroenteritis (AGE) occurs year-round, norovirus has a winter seasonality in the United States. OBJECTIVE: We analyzed norovirus seasonality within a US integrated healthcare delivery system from 2016-2019. METHODS: Electronic medical records were collected for acute gastroenteritis (AGE) encounters with specific ICD-9/10 codes or clinical stool testing. Norovirus percent positivity was calculated as the 8-week centered rolling average. Temperature and absolute humidity data were measured via weather station. The relationship between these factors and weekly norovirus episodes were modeled via negative binomial models. RESULTS: From 2016-2019, there were 198,181 AGE episodes reported; among the 18,998 episodes tested, 892 (5%) were norovirus positive. Norovirus percent positivity peaked in epidemiologic week 7 at 9%. Two negative binomial models showed significant inverse relationships between weekly number of norovirus episodes and both temperature and absolute humidity. CONCLUSION: Norovirus AGE exhibited winter seasonality from 2016-2019, associated with lower temperatures and humidity. Understanding this seasonality may help predict peak transmission periods and their impact on healthcare resources.

Source: PLoS ONE

DOI: 10.1371/journal.pone.0318077