Noroviruses are significant etiological agents of acute gastroenteritis (AGE) across all age groups, especially in children under 5 years of age. Although the prevalence of norovirus infection is known to have increased in various countries, in India there are few reports pertaining to the norovirus disease burden. We investigated the epidemiology and molecular characteristics of noroviruses in children seeking health care at two hospitals in Kolkata, Eastern India. Faecal specimens were collected between January 2018 and December 2019 from 2812 children under 5 years of age with acute gastroenteritis. Noroviruses were detected in 6.04% (170/2812) of the samples, and 12.9% (22/170) of these were cases of coinfection with rotavirus. Among children (≤5 years), a higher infection rate (8.2%, n = 94/1152) was observed in the 6 to 12 month age group. GII.4 Sydney 2012 was the dominant norovirus capsid genotype (n = 75/90, 83.3%), followed by GII.3 (n = 10/90, 11.1%). Other capsid types GII.13 (n = 4/90, 4.4%) and GII.17 (n = 1/90; 1.1%) were also detected at low frequency. Phylogenetic analysis showed that the GII.P16 polymerase of strains in this region clustered with those of the phylogenetically distinct monophyletic clade of GII.P16 strains, whose members have been circulating worldwide since 2014. Inter-genotypic norovirus recombinants such as GII.P16-GII.3 (n = 10) and GII.P16-GII.13 (n = 4) were also observed among the circulating strains. In comparison to previous studies from eastern India, the present study shows a higher detection rate of norovirus infection in the paediatric population suffering from acute gastroenteritis. Continuous surveillance is required for predicting the emergence of novel genotypes and recombinant strains and for future vaccine development.

诺如病毒是所有年龄组急性胃肠炎 (AGE) 的重要病原体，尤其是 5 岁以下儿童。尽管已知诺如病毒感染的流行在各个国家有所增加，但在印度，关于诺如病毒疾病负担的报道很少。我们调查了在印度东部加尔各答的两家医院就医的儿童中诺如病毒的流行病学和分子特征。在 2018 年 1 月至 2019 年 12 月期间，从 2812 名 5 岁以下患有急性胃肠炎的儿童中收集了粪便样本。在 6.04% (170/2812) 的样本中检测到诺如病毒，其中 12.9% (22/170) 是轮状病毒合并感染的病例。在儿童（≤5 岁）中，6 至 12 个月年龄组的感染率较高（8.2%，n = 94/1152）。GII.4 Sydney 2012 是主要的诺如病毒衣壳基因型（n = 75/90, 83.3%），其次是 GII.3（n = 10/90, 11.1%）。其他衣壳类型 GII.13 (n = 4/90, 4.4%) 和 GII.17 (n = 1/90; 1.1%) 也以低频检测到。系统发育分析表明，该区域菌株的 GII.P16 聚合酶与 GII.P16 菌株的系统发育不同的单系进化枝的聚合酶聚集在一起，其成员自 2014 年以来一直在世界范围内流行。基因型间诺如病毒重组体，如 GII.P16-GII在循环菌株中也观察到 .3 (n = 10) 和 GII.P16-GII.13 (n = 4)。与印度东部先前的研究相比，本研究表明，在患有急性胃肠炎的儿科人群中，诺如病毒感染的检出率更高。