Epidemiological Study On Viral Diarrhea Among Infants And Young Children In Lanzhou From2010to2011

Part1:Epidemiological Study on Common Diarrheal Viruses among Infants and Young Children in Lanzhou from2010to2011Objectives:The common viral agents of diarrhea are group A rotavirus, Calicivirus, Adenovirus and Astrovirus among infants and young children. To provide the evidence for prevention and treatment to viral diarrhea, a epidemiological study on these viruses was conducted in Lanzhou, China, from2010to2011.Methods:Stool specimens were collected between July2010and June2011from295children less than5years old with acute gastroenteritis who were admitted to the First Hospital of Lanzhou University. Rotavirus was detected using ELISA kit and typed by nested RT-PCR. Adenovirus was detected by PCR and typed by nested PCR and multiple PCR using primers targeted to the hexon gene and fiber gene, whereas calicivirus (norovirus GⅠ, GⅡ and sapovirus) and Astrovirus were determined by RT-PCR.Results:1.Of the295specimens,61.4%were positive for the common diarrheal viruses. Sequencing and phylogenetic analysis revealed that44.7%(132/295) were group A rotavirus,13.2%(39/295) were calicivirus,5.1%(15/295) were adenovirus and4.7%(14/295) were human astrovirus, respectively. The results of typed indicated that G1(36.4%) was the dominant serotype in rotavirus serotype, followed by G9(31.1%).Within the P genotype, P[8](74.2%) was the most common genetype,6.8%were P[4]. The common G-P combination was G1P[8](29.5%). The most prevailing calicivirus was norovirus (69.2%),13cases were norovirus GⅡ-3and12cases were GⅡ-4. Norovirus GI was not detected in this study. Adenovirus belonged to four subgenera (A,B,C and F) with five serotypes(Ad31, Ad3, Ad5, Ad6and Ad41), within these serotypes, Ad41(10/15) was the most prevaling serotype. Human astrovirus serotype1(64.3%) was the leading strain in all astrovirus positive cases.2. Of all viruses-positive cases, the rate of mix-infections was10.5%(19/181). Sixteen cases were confirmed co-infected with rotavirus. In these cases, three were norovirus GⅡ infections, three were saporovirus, five were astrovirus and five were adenovirus, respectively. eleven others were classic human astrovirus infections. One case was positive for both norovirus GⅡ and adenovirus, and two cases were positive for both saporovirus and adenovirus. In seasonal distribution, rotavirus and Calivirus positive samples mainly were observed in winter and spring, but Adenovirus and Astrovirus maily detected in spring and summer during the study period. These viruses predominantly infected children less than2years old.Conclusion:This study indicated the impact of viral agents causing diarrhea, and rotavirus was the most prevailing virus. The percentage of rotavirus G9and norovirus GII-3increased distinctly, their potential impact on public health should be more attention and long-term systematic surveillance was important. Objectives:Human novel astrovirus were recently identified in stool samples of diarrheal or normal children, and subsequently were detected in serum of child with fever. They were thought to be an etiologic agent of gastroenteritis or respiratory infection in children. Due to the limit data about epidemiological study in our country, whether these novel astroviruses were circulating in China remains unclear. The aim of this study was to investigate the prevalence of them in Lanzhou and Nanjing and understand their clinical characteristics.Methods:Stool specimens were collected between July2010and June2011from723children less than5years old with acute gastroenteritis who were admitted to the First Hospital of Lanzhou University and Nanjing Children’s Hospital and stored at-80℃until further analysis. All specimens were detected by OneStep RT-PCR using the primers SF0073/SF0076, which targeted a (?)409bp fragment of ORF1b of astroviruses. Then the positive samples were subjected to type with specific primers. These specific primers were designed based on the capsid gene of astroviruses. The nucleotide sequences were determined and analyzed using the software package DNAStar and MEGA version4.0. Statistical analyses were performed by using SPSS, version17.0.Results:Of the723stool specimens,11(1.5%) astroviruses were newly identified species. There was no statisticaolly significant (χ2=1.547,P=0.214) between the rates of Lanzhou and Nanjing. Among them,7were AstV-MLB1,2were AstV-MLB2and2were HMOAstV-A. None of the AstV-VA1, VA2, VA3and HMOAstV-B or C were detected. Of all astrovirus-positive cases,14(43.8%) cases were confirmed co-infected with rotavirus. In these cases,3were AstV-MLB1infections and11others were classic human astrovirus infections. No co-infection cases with calicivirus or adenovirus were found. In the terms of the mean age, duration of diarrhea, rates of fever and vomiting and frequency of diarrhea, there were no significant differences between the novel astrovirus group and classic astrovirus group (P>0.05).Conclusion:The results demonstrated that multiple astroviruses were circulating in Lanzhou and Nanjing, China. Our data suggested that these novel astroviruses might play etiological roles in the process of gastroenteritis in children, the correlation between these novel astroviruses and gastroenteritis needs to be further investigated.