Stool samples were collected in sterile tubes, transferred to the laboratory, and stored at −70°C until further processing. Stool samples were diluted to 10% (w/v) with phosphate-buffered saline and centrifuged. Viral double stranded RNA and DNA were extracted from the supernatant using the QIAamp MiniElute Virus Spin Kit (Qiagen, Hilden, Germany). PCR was performed to detect adenovirus (15 (link)) and reverse transcription PCR (RT-PCR) was performed to detect rotavirus (8 (link)), norovirus (16 (link)), and astrovirus (17 (link)) as described previously (18 ). Multiplex PCR using a Seeplex Diarrhea-V ACE detection kit (Seegene Inc., Seoul, Korea) was also performed to detect astrovirus, group A rotavirus, enteric adenovirus, and norovirus, according to the manufacturer's instructions (19 (link)). Amplification products were examined by electrophoresis on 1.5% agarose gels and documented with the Bio-Rad Gel Doc 1000 Documentation System (BioRad, Hercules, CA, USA). The samples were scored as positive for rotavirus if the rotavirus antigen test and/or PCR reactions were positive. The samples were scored as positive for norovirus, adenovirus, or astrovirus if the PCR reactions were positive.