[Clinical characteristics of diarrhea caused by rotavirus A in children under 5 years old in China, 2009-2020].

Objective: To analyze the clinical characteristics and severity of diarrhea caused by rotavirus A (RVA) in children aged <5 years in China from 2009 to 2020, and provide evidence for the clinical diagnosis, treatment, prevention and control of RVA-caused diarrhea. Methods: Based on the infectious disease surveillance technology platform of China CDC, the data of etiological surveillance of diarrhea syndromes carried out by 252 sentinel hospitals in 28 provinces (autonomous regions, municipalities) of China from January 2009 to December 2020 were collected, including the basic information, clinical characteristics of the cases, stool sample detection results of RVA by ELISA, and virus genotyping data from RT-PCR. Vesikari score and descriptive epidemiological methods were used to analyze viral infection status, clinical characteristics, and symptom severity in children aged <5 years with diarrhea. Results: A total of 55 637 diarrheal children under five years old were included in RVA detection from 2009 to 2020, in whom 15 945 (28.66%) cases were positive. In the children with diarrhea, the positive rate in those with severe diarrhea was 32.25%, which was higher than that in those with mild diarrhea (26.88%). The positive rate in the cases with watery stool was 31.44%, higher than that in cases with stool of other characteristics (23.33%). The positive rate in children with vomiting was 41.65%, significantly higher than that in those without vomiting (23.67%). The RVA positive rate was highest (46.85%) in children with severe vomiting, with the highest positivity rate beingobserved in bloody vomitus (54.26%), and there were significant differences in positive rates among different types of vomitus (P<0.001). The positive rate in dehydrated children was 36.94%, higher than that in non-dehydrated children (28.41%) (P<0.001). Among different clinical characteristics, the proportions of watery stool induced by genotypes G2P[4] and G9P[8] were relatively high (78.81% and 78.77%). Genotype G3P[8] had the highest proportion of vomiting cases (57.72%), while genotype G9P[8] was more prominent in the cases with fever (36.56%) and dehydration (14.57%). Symptoms caused by genotype G1P[8] were relatively mild. Among RVA-positive children evaluated by the Vesikari score, the proportion of mild cases was highest in those aged 0- months (80.36%). The proportion of severe cases was highest in those aged 6- months age group (9.11%) and the proportion decreased to 6.64% in those aged 24-59 months. In severe cases, genotype G9P[8] accounted for the highest proportion (17.23%). Moderate cases were mainly caused by genotype G3P[8] (36.14%), while mild cases had highest proportion of genotype G1P[8] (76.49%). Conclusions: In China, the frequency of diarrhea, stool characteristics, vomiting, and dehydration symptoms of diarrhea cases were significantly associated with the RVA positive rate in children aged <5 years old. The clinical features induced by different RVA genotypes in the sick children varied. The risk of G9P[8] genotype-caused severe diarrhea was high. Children aged 6-23 months were prone to have severe illness. Therefore, effective RVA prevention and treatment measures should be developed to target children in different age groups and with different genotype infections.