The molecular epidemiology of human group A rotavirus infections in children in Hangzhou in 2017

Objective To analyze the infectious status and genotype characteristics of group A rotavirus (RV) in children with diarrhea in Hangzhou city in 2017, and to provide information for the disease surveillance, epidemic control as well as vaccine development. Methods Fecal samples from children with acute diarrhea at Children′s Hospital of Zhejiang University were collected from Jan to Dec in 2017. All samples were tested for RV antigen by emulsion technique. The antigen-positive samples were further detected by reverse transcription polymerase chain reaction (RT-PCR) and sequencing to determine the G and P genotypes. The RV positive rates in different genders, ages and months were compared by chi-square test. Results A total of 20 895 fecal samples were collected from 12 389 male patients and 8 506 female patients. The gender ratio was 1.46∶1. In 5 012 (23.99%) RV antigen positive samples, 2 964 (23.92%) were from male patients and 2 048 (24.08%) were from female patients. There was no gender difference in RV positive rate (χ2=0.049, P>0.05). In the study, RV could be detected in the whole year. January, February and December were peak months, and the RV positive rates were significantly different in different months (χ2=2 654.681, P<0.05). The highest RV positive rate was in 18-24 months age group and the lowest in<6 months age group, respectively. Children under 2 years old accounted for 76.56% RV positive cases, and those under 5 years old accounted for 98.72% RV positive cases. The RV positive rates were also significantly different in all age groups (χ2=1 013.832, P<0.05). A total of 116 samples were selected from each month, following the random stratified sampling principle, for PCR amplification, sequencing, and genotyping according to VP7 (G genotype) and VP4 (P genotype). A total of 4 G genotypes were detected and G9 (85.3%) was the predominant one. In the two detected P genotypes, P[8] (96.6%) was predominant. The 4 G/P combination genotypes were G9P[8] (85.3%), G3P[8] (9.5%), G2P[4] (3.5%), and G1P[8](1.7%). Conclusions RV was a common pathogen in pediatric patients with acute diarrhea in Hangzhou city in 2017. Children under 5 years old, especially 18 months to 2 years old infants was the main infected population. The study showed RV infection had obvious seasonality and winter was the peak period. The G9 genotype was predominant in G genotypes, P[8] genotype was predominant in P genotypes, and G9P[8] genotype was predominant in G/P combination genotypes, respectively. Key words: Rotavirus infections; Diarrhea; Genotype; Epidemiologic studies; Child