Etiological and epidemiological characteristics of viral diarrhea in children under 5 years old in a sentinel hospital in Hangzhou, Zhejiang, 2012–2019

ObjectiveTo analyze the pathogenic spectrum and epidemiological characteristics of viral diarrhea in children under 5 years old in Hangzhou and its surrounding areas of Zhejiang province from 2012 to 2019 and provide evidence for the prevention and control of viral diarrhea.

MethodsFrom 2012 to 2019, stool samples were collected from children aged <5 years with diarrhea in the outpatient and emergency department of Children's Hospital of Zhejiang University School of Medicine for the nucleic acid detections of norovirus (NV), rotavirus (RV), sapovirus (SAV), enteric adenovirus (EADV) and astrovirus (ASV) by real-time fluorescent quantitative PCR (quantitative real-time PCR). Statistical software SPSS 19.0 was used to analyze the results.

ResultsA total of 1 350 stool samples were collected, in which 594 were positive for the viruses. The overall infection rate was 44.00%. A majority of the samples were single virus positive (84.51%, 502/594), while 14.31% and 1.18% of the samples were positive for two and three viruses, respectively. NV and RV co-infections accounted for 54.12%, (46/85). The infection rate of NV was highest (23.41%), followed by that of RV (19.11%). The detection rates of SAV, EADV and ASV were less than 5% (4.22%, 2.96% and 1.63%, respectively). There were significant differences in the virus detection rate among children with diarrhea among different age groups ( χ²=256.140, P<0.001). The age group 12-23-months had the highest detection rate (73.77%, 239/324), but the age group under 6-months had the lowest detection rate (17.18%, 73/425). There were significant differences in the detection rate of each virus among different age groups. The overall virus detection rate exhibited significant seasonal differences ( χ²=188.495, P<0.001), and peaked (70.31%, 225/320) in winter (i.e., December - February). The differences in the detection rates of NV, RV and SAV among different seasons were significant ( χ²=90.284, P<0.001; χ²=188.068, P<0.001; χ²=29.066, P<0.001), and the detection rate of NV peaked in autumn (September - November), while the detection rates of RV and SAV peaked in the winter. Between 2012 and 2019, the detection rate was higher in odd-numbered years than in previous even-numbered years, and the overall detection rate showed an upward trend (trend χ²=13.532, P<0.001). The annual changes in the detection rates of NV and ASV also showed upward trends (trend χ²=23.636, P<0.001; trend χ²=18.073, P=0.003). The changes in annual detection rates of RV, SAV and EADV were irregular (trend χ²=3.173, P=0.075; trend χ²=1.803, P=0.179; trend χ²=0.007, P=0.932).

ConclusionThe main pathogens of viral diarrhea in children under 5 years old were NV and RV. The incidences of infections in infants and young children aged 12–35 months were high in autumn and winter. It is necessary to strengthen the prevention and control of viral diarrhea in autumn and winter.