Human Parechovirus and Other Enteric Viruses in Childcare Attendees in the Era of Rotavirus Vaccines

Objective. We studied the prevalence of enteric viruses, including rotavirus, enterovirus, norovirus, adenovirus, and human parechovirus (HPeV), in stool samples of childcare attendees. The prevalence of enteric viruses was described in children with and those without gastroenteritis. Methods. Children aged 1-19 months were recruited from 2 childcare centers in Tacoma, Washington, from October 2008 through June 2009. Stool samples were obtained at enrollment and during diarrheal illnesses for enteric virus testing. A symptom diary was completed by parents. Results. One hundred six children (mean age, 10 months) were followed for an average of 170 days. At enrollment, 78 asymptomatic children had stool samples available. Forty-eight illnesses with acute diarrhea (stool samples were available for 24 illnesses) occurred in 37 children. Rotavirus was not detected in samples from symptomatic or asymptomatic children. HPeV was present in 21% and adenovirus in 46% of symptomatic children. At least 1 virus was detected in 78% of samples from asymptomatic children, including HPeV in 27% and adenovirus in 55%. No differences were found in symptom prevalence between HPeV-positive and HPeV-negative diarrheal illnesses. Molecular analysis revealed a diversity of HPeV types. Conclusions. Our study highlights the high level of HPeV circulation in childcare. The lack of rotavirus detected in this study supports the impact of rotavirus vaccine and emphasizes the need for a greater focus on the epidemiology of non-rotavirus etiologies of gastroenteritis. The detection of enteric viruses in children who attend childcare that utilizes sensitive molecular diagnostic techniques has not been prospectively assessed, particularly in the era of widespread uptake of rotavirus (RV) vaccines. Previous studies have documented extremely prevalent RV infection in children attending childcare prior to the introduction of the RV vaccine. In the late 1980s, 318 children in childcare centers in Houston, Texas, experienced 362 episodes of RV diarrhea over a 3-year period [1–3]. Since the recommendation for routine RV vaccination by the Advisory Committee on Immunization Practices in 2006, surveillance studies have documented a dramatic and sustained decrease in RV disease throughout the United States [4, 5]. Following the decline in RV disease, current rates of RV gastroenteritis in childcare centers, as well as those of diarrhea associated with noroviruses (NVs), enteroviruses (EVs), adenoviruses (AVs), and the newly reclassified viruses now known as human parechoviruses (HPeVs), are not known. HPeVs are a viral genus in the Picornaviridae family. The oldest described members of the