Abstract Title
Comparing Norovirus Gastroenteritis in Medically-Attended Patients and Community-Cohort in Central Wisconsin, United States
Presenter
Joshua Petrie, Marshfield Clinic Research Institute
Co-Author(s)
Huong Q. Nguyen, Jennifer P. King, Oluwakemi D. Alonge, Edward A. Belongia, Evan J. Anderson, Wen-Hsing Wu, Christine Kim, Katherine B. Carlson
Abstract Category
Epidemology
Abstract
The proportion of norovirus gastroenteritis (NGE) caused by genotype GII.17[P17] increased in 2023-2024. As of January 2025, GII.17[P17] was detected in 79% of norovirus (NoV) outbreaks reported in the United States.
During the 2024-2025 season, we performed two studies to investigate incidence and outcomes of NGE. The first study (Cohort) conducted active surveillance for acute gastroenteritis (AGE) in a community cohort (14OCT2024 – 16FEB2025). The second study (MA) recruited patients with medically-attended AGE in the outpatient or hospital setting (25AUG2024 – 21FEB2025). Both studies collected stool from ill participants for NoV testing by RT-PCR; genotype was determined by Illumina sequencing. Participants completed surveys to report symptoms and impact on daily activities.
Among 1,505 Cohort participants, 191 (13%) reported AGE and 51 (27%) of these tested NoV positive; 7 of 51 cases (14%) reported seeking medical care. In the MA study, 155 outpatients and 31 inpatients with AGE were enrolled; 19 (12%) and 10 (32%) had NoV identified, respectively. The median (IQR) age of Cohort study NGE cases was 23 (2, 50) years and 29 (7, 52) years for MA study NGE cases. Norovirus GII.17[P17] represented 30 of 45 (67%) and 18 of 21 (86%) (n=18) of successfully sequenced NoV in the Cohort and MA studies, respectively. Median (IQR) symptom severity scores were 8 (6, 9) for GII.17 and 7 (6, 8) for other GII genotypes.
NoV was detected in 27% of community, 12% of outpatient, and 32% of inpatient AGE illnesses representing substantial burden during the GII.17-predominant 2024-2025 season.
During the 2024-2025 season, we performed two studies to investigate incidence and outcomes of NGE. The first study (Cohort) conducted active surveillance for acute gastroenteritis (AGE) in a community cohort (14OCT2024 – 16FEB2025). The second study (MA) recruited patients with medically-attended AGE in the outpatient or hospital setting (25AUG2024 – 21FEB2025). Both studies collected stool from ill participants for NoV testing by RT-PCR; genotype was determined by Illumina sequencing. Participants completed surveys to report symptoms and impact on daily activities.
Among 1,505 Cohort participants, 191 (13%) reported AGE and 51 (27%) of these tested NoV positive; 7 of 51 cases (14%) reported seeking medical care. In the MA study, 155 outpatients and 31 inpatients with AGE were enrolled; 19 (12%) and 10 (32%) had NoV identified, respectively. The median (IQR) age of Cohort study NGE cases was 23 (2, 50) years and 29 (7, 52) years for MA study NGE cases. Norovirus GII.17[P17] represented 30 of 45 (67%) and 18 of 21 (86%) (n=18) of successfully sequenced NoV in the Cohort and MA studies, respectively. Median (IQR) symptom severity scores were 8 (6, 9) for GII.17 and 7 (6, 8) for other GII genotypes.
NoV was detected in 27% of community, 12% of outpatient, and 32% of inpatient AGE illnesses representing substantial burden during the GII.17-predominant 2024-2025 season.