Molecular epidemiology of human calicivirus infections in children with acute diarrhea in Shanghai: a retrospective comparison between inpatients and outpatients treated between 2006 and 2011.

Human caliciviruses (HuCVs), especially noroviruses, are currently the second leading cause of acute diarrhea in children; however, data are limited in Shanghai and other regions of the world regarding the epidemic difference of HuCV infections between inpatients and outpatients. Fecal samples (n = 1110) were collected from children up to age 5 years with acute diarrhea treated as inpatients or outpatients at Children's Hospital of Fudan University in Shanghai, between 2006 and 2011. Human calicivirus was detected and genotyped using an RT-PCR assay for the RdRp gene. Among inpatients, 206 HuCV-positive samples (30.6 %) were detected as positive for norovirus. The predominant norovirus genotype was GII.4 (75.5 %), followed by GII.12 (22.3 %), GII.7 (1.0 %), and GII.b (1.0 %). Among outpatients, 128 samples (29.4 %) were positive for HuCV. Of these, 126 were positive for norovirus and two were positive for sapovirus. The predominant norovirus genotypes causing infections in outpatients were GII.4 (71.8 %) and GII.b (15.6 %), followed by GII.12 (9.5 %), GII.7 (0.8 %), and GII.2 (0.8 %). The GII.4-2006b variant was the predominant subtype both in inpatients and outpatients. Characteristics of the HuCV epidemic differ between inpatients and outpatients. Continued surveillance is vital to determine the molecular prevalence of HuCV and to develop effective vaccines.