Related Experiment Video
Updated: Jan 7, 2026

High-throughput Detection Method for Influenza Virus
Published on: February 4, 2012
County-Level Influenza-Attributable Emergency Department Visits and Their Spatial Correlates in the United States:
Xucheng Fred Huang1, Joshua L Warren2, Shuqi Lin2
1Gangarosa Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA, United States.
Background:
The burden of seasonal influenza on emergency department (ED) visits is poorly quantified due to case ascertainment and data availability challenges. This study estimates county-level respiratory ED visits attributable to influenza using time-series models and examines spatial heterogeneity in county-level burden in 3 states.
Objective:
This study aimed to estimate the county-level respiratory ED visits attributable to influenza using time-series models and examine spatial heterogeneity in county-level burden in 3 states.
Methods:
We used daily hospital discharge records to measure community-level influenza activity in California (2005-2018), Georgia (2010-2018), and New York (2005-2018). County-level respiratory ED visit rates attributable to influenza were estimated by quasi-Poisson time-series models, adjusting for temporal trends and environmental factors. Bayesian spatial models were used to assess associations with county-level socioeconomic status, environmental exposures, and chronic health condition prevalence.
Results:
Influenza-attributable respiratory ED visit rates per 100,000 population were 226 (95% CI 206-246) in New York, 232 (95% CI 206-259) in California, and 547 (95% CI 506-589) in Georgia. A 10% increase in county-level poverty and uninsured rates was associated with higher influenza burden, increasing influenza-attributable respiratory ED visit rates by 160 (95% credible interval [CrI] 127-196) and 217 (95% CrI 168-265), respectively. Long-term PM2.5 (fine particulate matter ≤2.5 µm), humidity, and temperature also exhibited positive associations. Chronic conditions also increased ED visit rates by 1476/100,000 (95% CrI 1167-1778), 588/100,000 (95% CrI 400-747), and 488/100,000 (95% CrI 402-574) per 10% increase in stroke, chronic obstructive pulmonary disease, and diabetes prevalence, respectively. These associations weakened after adjusting for socioeconomic status.
Conclusions:
Influenza-attributable respiratory ED visit rates exhibit significant spatial heterogeneity that is associated with county-level socioeconomic factors, environmental exposures, and chronic disease prevalence.
Related Concept Videos
Steps in Outbreak Investigation
Principles of Disease Surveillance
Causality in Epidemiology
Statistical Methods for Analyzing Epidemiological Data
Introduction to Epidemiology
Bias in Epidemiological Studies

