Novovirus infection and genotype in young children in Guangzhou,2008

Objective To describe epidemiologic characteristics of novovirus infection and its genotype in children under 5 years in Guangzhou.Methods Stool specimens and clinical data were collected from 692 outpatients with clinically-diagnosed viral diarrhea from five surveillance hospitals in 2008.Specimens were tested for antigens of rotavirus,adenovirus,norovirus,and astrovirus by ELISA,and those positive for norovirus were subject to reverse transcription polymerase chain reaction(PCR).Positive PCR products were purified and sequenced,and the sequences were compared to GenBank data to identify genotype.Results Of all 692 specimens,31.9%(221),21.2%(147),6.1%(42),and 1.2%(8) were positive for antigens of rotavirus,norovirus,adenovirus,and astrovirus,respectively.Mixed infection accounted for 6.8%(47/692) of all cases.For norovirus cases,there was a peak of occurrence during September to November,which corresponded to 51.7%(76/147) of all cases;children under 2 years accounted for 91.8%(135/147) of all cases;main clinical symptoms were diarrhea,vomiting,fever,and abdominal pain.Nucleic acid of norovirus was detected in 84.4%(124/147) of the specimens positive for norovirus antigen,and all strains belonged to genotype GⅡ4,except for one(GⅡ2).Conclusion Norovirus is only second to rotavirus in the frequency of causing viral diarrhea in children under 5 years of age in Guangzhou.Norovirus infection is clinically common in infants under 2 years old,and GII4 is the predominant genotype in the population studied.