Changing pattern of prevalence and genetic diversity of rotavirus, norovirus, astrovirus, and bocavirus associated with childhood diarrhea in Asian Russia, 2009-2012.

This hospital-based surveillance study was carried out in Novosibirsk, Asian Russia from September 2009 to December 2012. Stool samples from 5486 children with diarrhea and from 339 healthy controls were screened for rotavirus, norovirus, astrovirus, and bocavirus by RT-PCR. At least one enteric virus was found in 2075 (37.8%) cases with diarrhea and 8 (2.4%) controls. In the diarrhea cases, rotavirus was the most commonly detected virus (24.9%), followed by norovirus (13.4%), astrovirus (2.8%) and bocavirus (1.1%). Mixed viral infections were identified in 4.3% cases. The prevalence of enteric viruses varied every season. Rotavirus infection was distributed in a typical seasonal pattern with a significant annual increase from November to May, while infections caused by other viruses showed no apparent seasonality. The most common rotavirus was G4P[8] (56%), followed by G1P[8] (20.1%), G3P[8] (5.5%), G9P[8], G2P[4] (each 1.3%), six unusual (1.2%), and five mixed strains (0.5%). Norovirus GII.3 (66.5%) was predominant, followed by GII.4 (27.3%), GII.6 (3.7%), GII.1 (1.6%), and four rare genotypes (totally, 0.9%). Re-infection with noroviruses of different genotypes was observed in four children. The classic human astrovirus belonged to HAstV-1 (82%), HAstV-5 (8%), HAstV-4 (4.7%), HAstV-3 (4%) and HAstV-2 (1.3%). Consecutive episodes of HAstV-1 and HAstV-4 infections were detected in one child with an 8-month interval. Bocavirus strains were genotyped as HBoV2 (56.5%), HBoV1 (38.7%), HBoV4 (3.2%) and HBoV3 (1.6%). In the controls, norovirus strains belonged to GII.4 (n = 4), GII.1, GII.3, and GII.6, and HBoV2 strain were detected. Most of the detected virus isolates were characterized by a partial sequencing of the genomes. The genotype distribution of most common enteric viruses found in the Asian part of Russia did not differ considerably from their distribution in European Russia in 2009-2012.

Human bocavirus in hospitalized children with acute gastroenteritis in Russia from 2010 to 2012.

Human bocavirus (HBoV) can cause respiratory diseases and is detectable in the stool samples of patients with gastroenteritis. To assess the prevalence of HBoV in children hospitalized with acute gastroenteritis in Novosibirsk, Russia, as well as its genetic diversity and the potential role in the etiology of gastroenteritis in this region, a total of 5502 stool samples from children hospitalized with gastroenteritis from 2010 to 2012, n=5250, and healthy children, n=252, were assayed for the presence of HBoV DNA by semi-nested PCR. The HBoV DNA was found in 1.2% of stool samples from children, with gastroenteritis varying from 0.5% in 2012 to 1.7% in 2011. The prevalence of HBoV in healthy children was 0.3%. HBoV strains were detected throughout the year with an increase in the fall-winter season. In 87% of cases, HBoV was detected in children before 1 year of age. All known HBoV genetic variants have been detected in Novosibirsk, although with different prevalences: HBoV2>HBoV1>HBoV4>HBoV3. At the beginning of 2011, HBoV2 replaced HBoV1 as the most prevalent variant. The median age of children with detected HBoV1 was 8.3months, and that with HBoV2 was 8.0 months. All HBoV-positive samples were assayed for the presence of the rotaviruses A and C, norovirus GII, astrovirus, enterovirus, adenovirus F, Salmonella spp., Campylobacter spp., Shigella spp., and EIEC. HBoV1 and HBoV2 as single agents were found in 45.8% and 60% samples, respectively, although this difference was not statistically significant. In the case of co-infections, HBoV was most frequently recorded with rotavirus A and norovirus GII. This study demonstrated that the detection rate of HBoV in stool samples from children with gastroenteritis was low, although both HBoV1 and HBoV2 could be found as the sole agents in children with gastroenteritis in Novosibirsk.