Epidemiology and Clinical Characteristics of Adult Astrovirus Gastroenteritis in Metropolitan Washington DC, USA: 2016-2023

Abstract Introduction/Objective Astrovirus gastroenteritis is commonly studied in children but not adults. Detection of astrovirus on PCR panels allows for characterization of infected patients. Here, we investigate the epidemiology and clinical characteristics of adult astrovirus infections at our institution. Methods/Case Report Stool specimens tested between 01/2016-03/2023 on a gastrointestinal PCR panel (BioFire Diagnostics, Salt Lake City, UT) were analyzed. Chart abstraction was performed to collect patient demographics, laboratory results, clinical presentation and management for patients positive for astrovirus. Fisher Exact Test and 95% Confidence Intervals were calculated where appropriate. Results (if a Case Study enter NA) Overall positivity rate of astrovirus was 0.6% (34/5053) with highest (1.02%) in 2018 and none in 2020. The mean age was 32 years old (range:18-52 yo) with majority being Caucasian (56%) and female (56%). Symptoms included diarrhea (100%), abdominal pain (92%), vomiting (47%), and fever (35%). Comparing patients in age group 30-39 years versus other age groups, vomiting (21% vs 65%, p=0.0173) and fever (40% vs 67%, p=0.717) were less prevalent. More females had abdominal pain (95% vs 87%, p=0.6) while more males had fever (47% vs 26%, p=0.3) although insignificant. Average period of diarrhea was 3 days (range:1-10 days). 23.5% of patients had increased monocytes (CI 0.29-1.92 x 103/µl), and 29.4% showed decreased lymphocytes (CI 0.29-1.10 x 103/µl). Peak seasons were late winter to spring (February-April). All patients were immunocompetent except one (HIV+). Gastrointestinal co-infections included toxigenic E. coli (12%), C. difficile (6%), Campylobacter (3%), Norovirus (3%), Salmonella (3%) and Stronglyloides (3%). In all 34 patients, clinicians acknowledged detection of astrovirus and discharged patients without antibiotics. Conclusion To our knowledge, this is the first case series on adult astrovirus infections from the D.C. area. We report novel findings about adult astrovirus gastroenteritis that are different from observations in children. PCR can rapidly diagnose viral gastroenteritis and can reduce inappropriate antibiotic administration.