Molecular Epidemiology Study Of Pediatric Norovirus Gastroenteritis In Chongqing, 2015

Objective To study the prevalent situation and manifestation of norovirus gastroenteritis in children, and analyze the molecular epidemiology and recombination in Chongqing, 2015.Methods We collected fecal samples and record the clinical data from485 children with acute gastroenteritis in the outpatient department of Children’s hospital of Chongqing Medical University from January to December in 2015. We detected the nucleic acid about major capsid protein gene of No V genogroup GI and genogroup GII by RT-PCR,then sequencing all the positive products and then analyzed the genotypes and structure the phylogenetic tree and the prevalence of the positive samples by categorized month, sex, and age. In addition, we amplified partial Rd Rp and major Capsid protein gene of all the positive products and then sequencing, and analyzed the genotypes and recombination.Results 485 specimens were collected. The positive rate of No V is10.7%(52/485), all the 52 positive are genogroup GII, no one was positive for genogroup GI. No V prevalence major from August to October,and the No V detection rate between different month was significantly difference(χ2=41.514, P < 0.05). And the male positive rate was 12.9%(36/279), the females positive rate was 7.8%(16/206). The detection rateof females and males was no statistical difference(χ2=3.266,P>0.05). The detection rate in the age group younger than 6 months was lower than other groups. There was a higher detection rate and constituent ratio in the age group between seven to twelve months. And Children younger than 2 years old accounted for 88.5% of the total positive cases. Most of the No V positive children have watery stool. Dirarrhea was the only symptom in23.1%(12/52) children, and the other 65.4%(34/52)had accompanied with vomiting. The positive rate of respiratory and fever were 38.5%(20/52) and26.9%(14/52). There were 27(51.9%) GII.4 Sydney 2012,16(30.8%)GII.3, 5(9.6%) GII.6, 2(3.8%)GII.7, 2(3.8%)GII.17. We detected3 No V GII recombination types consisting of 21 GII.e|GII.4 Sydney 2012,9 GII.12|GII.3 and 2 GII.7|GII.6.Conclusions No V is a common cause of pediatric viral gastroenteritis in Chongqing. The epidemic peak of No V were August, September and October. And children younger than 2 years old accounting for 88.5% of the total positive cases. There was a higher detection rate in the age group between seven to twelve months. The prevalent strains of No V characterized by genetic diversity and commonly recombination.GII.e|GII.4 Sydney 2012, GII.P12|GII.3, GII.P7|GII.6, GII.P7|GII.7,GII.P17|GII.17 were the predominant strain in Chongqing, 2015.