Abstract and Introduction
Knowledge of the epidemiology of sporadic acute gastroenteritis (AGE) in the United States is limited. During September 2016–September 2017, we surveyed Kaiser Permanente Northwest members in Oregon and Washington, USA, to collect data on the 30-day prevalence of dually defined AGE and diarrhea disease and related health-seeking behavior; from a subset of participants, we obtained a stool specimen. Using the iterative proportional fitting algorithm with raked weights, we generated AGE prevalence and annualized rate estimates. We detected norovirus, rotavirus, astrovirus, and sapovirus from submitted stool specimens through real-time quantitative reverse transcription PCR (qRT-PCR). We estimated a 30-day prevalence of 10.4% for AGE and 7.6% for diarrhea only; annual rates were 1.27 cases/person/year for AGE and 0.92 cases/person/year for diarrhea only. Of those with AGE, 19% sought medical care. Almost one quarter (22.4%) of stool specimens from those reporting AGE tested positive for ≥1 viral pathogen, compared with 8.2% from those without AGE.
In the United States, the incidence of acute gastroenteritis (AGE) is high. AGE is estimated to cause 179 million illnesses annually.[1,2] Precise data are limited on the occurrence and characteristics of sporadic AGE, particularly because the illnesses are generally mild and usually do not require medical care; may not have had diagnostic testing even if care was sought; and, depending on the pathogen, may not be reportable through public health surveillance systems. Previous US publications, using data from the US Foodborne Diseases Active Surveillance Network (FoodNet), have reported AGE prevalence ranging from 7.7 to 11%, equivalent to roughly 0.7–1.4 illnesses/person/year, depending on the recall period (i.e., 7 or 28 days) and symptom profile (i.e., diarrheal illness alone or with the presence of additional symptoms).[1,3–5] These studies have been essential in establishing estimates of AGE incidence in the community and highlighting the substantial burden of disease. However, differences in AGE case definitions have complicated efforts to compare findings across studies and time periods, and robust estimates of occurrence across the age spectrum remain limited. Consequently, there is a need to obtain all-age, population-based estimates of AGE within the United States.
Even assuming the lowest reported AGE prevalence of 7.7%, there is potential for substantial disease burden on the local healthcare systems and on society, such as through lost productivity. Among persons with AGE, 12%–20% have reported visiting a healthcare provider to manage their symptoms, and AGE has been estimated to contribute to 2–3 million ambulatory visits and 900,000 hospitalizations per year in the United States.[1,3,4,7–10] However, these data have relied on samples of persons within a geographic area who may differentially seek care depending on if they have medical insurance or access to an affordable care source. As a result, these studies may not accurately estimate the true potential burden on a healthcare system.
Clarifying the etiology of AGE illness within communities and healthcare systems can help to effectively target prevention efforts. Sporadic cases of AGE are largely attributable to viral pathogens; norovirus is the most common cause of AGE across the age spectrum. Evidence in the literature suggests that intensity of viral shedding among those with asymptomatic norovirus infections is similar to that of symptomatic infections;[2,8,11] however, according to transmission modeling of a healthcare-associated outbreak, symptomatic shedders are more likely to transmit norovirus to others than those without symptoms.
To better characterize the incidence of AGE in the community, the associated healthcare utilization, and the prevalence of viral enteropathogens among both symptomatic and asymptomatic persons, we conducted the Community Acute Gastroenteritis (CAGE) Study among the membership population of a large, integrated healthcare system. The aims of the CAGE Study were to generate 30-day prevalence and annualized incidence estimates of AGE occurrence across the age spectrum, describe the proportion of symptomatic persons seeking healthcare, and calculate the prevalence of enteric viral pathogens among those who did and did not report AGE. To contextualize our results with previously reported literature, we report our findings here using 2 validated case definitions.[1,13]
Emerging Infectious Diseases. 2022;28(11):2234-2242. © 2022 Centers for Disease Control and Prevention (CDC)