Clinical And Molecular Epidemiology Of Rotavirus Infection In Neonates

[Objective] Rotavirus is the leading cause of severe diarrhea in young children worldwide. The disease is ubiquitous, almost every child have an episode of rotavirus infection by age 5. Every year about 600,000 children die from rotavirus, account approximately 5% of all deaths in children under 5 years of age worldwide. Of the total deaths more than 80% occurring in resource-poor countries in south Asia and sub-Saharan Africa; In developed countries such as America,30-70% hospitalizations for gastroenteritis are rotavirus caused, and is associated with direct and indirect costs of approximately $1 billion per year. In China, acute gastroenteritis caused by rotavirus account 30%-40%, also caused a great loss to Socio-economy and medical resources, seriously affected the health and life quality of infants and young children. Thus, both in developed and developing countries, rotavirus gastroenteritis is a serious public health problem. As no effective therapies are currently available, and there is no significant difference of rotavirus infection rate between industrialized and resource-poor countries, indicating that improvements in hygiene or the nutritional status of infants and young have little effect on virus transmission, So the primary public health intervention for rotavirus infection is vaccination, Rotavirus vaccination has become the primary task of the vaccine development program in World Health Organization. When mixed infection with more than one rotavirus strain occurs, the gene segments from the parental viruses may reassort independently, producing reassortants of mixed parentage, the reassort can occur between human strains or human and animal strains, resulting viral diversity. The rotavirus strains vary over time and regions,this will bring a challenge in vaccine development. Especially after the introduction of the vaccine, it may play a selective role in epidemic strains of rotavirus, induce the prevalence of a rare strain. So in-depth epidemiological investigation of rotavirus infection is needed, thus can detect the emergence of new epidemic strains in time, and provide better service for vaccine research. Comparing with infants and young children, neonatal rotavirus infection have different characteristics, mainly hospital-acquired infection and can Cause outbreaks in nursery, it is difficult to control, the same strain of the virus infection may last for several years. Somebody have hypothesized that RV strains infecting neonates may represent a possible source of emergence of new strains that subsequently spread in the local community. Therefore, the monitoring of rotavirus infecting newborns possibly provide early detection of the emergence of a new strain, timely internalize into vaccine research, then can prevent pandemic infections caused by unusual rotavirus strain. Previous studies about the changes of symbiotic intestinal flora in the gut during acute diarrhea primarily based on the classical method of fecal bacterial culture.An early study from this institution noted that during acute diarrhea fecal bacteria changed from predominance of anaerobes to a predominance of aerobes. However, study on the relationship between intestinal flora and rotavirus infection is relatively rare in domestic and foreign,moreover the results are controversial. This study investigated rotavirus infection in neonate in the year 2009,affiliated Children's Hospital of Zhejiang University,in order to understand the epidemiological characteristics of neonatal rotavirus, provide the basis of molecular epidemiology for vaccine research,and by detectingβ-glucosidase;β-glucuronidase and the urease activity in stools to understand the the gut microflora changes when rotavirus infection occurred.[Methods] We collected 100 Stool specimens from newborns who was diagnosed as rotavirus infection by Outpatient Laboratory during March to December 2009 in affiliated Children's Hospital of Zhejiang University. According to the gene sequences that encode group-specific antigen VP6, we design specific primer to amplification VP6-specific gene fragments with RT-PCR, and conduct agarose gel electrophoresis to determine rotavirus infection. The positive specimens then further for G, P genotyping. Design the specific primers of the most common strains G1-G4 for G genotype; P classification is mainly based on prevalent strains P [4], P [6], P [8] to design specific primers for RT-PCR..The results of gene amplification conduct agarose gel electrophoresis, according to the characteristic molecular bands to determine the genotype. Detecte fecal enzyme activity of urease,β-glucosidase andβ-glucuronidase in rotavirus gastroenteritis group and the control group respectly to observe changes in microflora of intestinal tract. Meanwhile, clinical data (include:Age, gender, delivery mode, feeding, diarrhea days, the maximum daily stool frequency, fever and vomiting) of two groups were statistically analyzed to understand the clinical features of neonatal rotavirus gastroenteritis.【Results】The genotype of rotavirus infecting newborns is G3P[8]. The urease and P-glucuronidase activity in the group of rotavirus infection are significantly higher than that in control group, there are statistically significant differences (P=0);β-gludosidase between two groups have no significant differences (P=0.256). The seasonal characteristics of neonatal rotavirus infection in Hangzhou are as follows:the peak season of nosocomial infections are from October to December and January to March; community-acquired rotavirus infection prevail in April, May and November. There are no statistically significant differences between CA-AGE and HA-AGE, preterm infants and term infants in clinical severity. Mode of delivery and feeding patterns have no difference on clinical severity (P>0.05). Neonates who infected RV within 7 days of birth have lower clinical severity score compared with the one who infected after 7 days of birth, the difference was statistically significant(P<0.05). When compared the main clinical symptoms of fever and vomiting, the frequency of the two symptoms between nosocomial infections and community acquired infections did not differ significantly (P>0.05), while increasing of stool frequency was significantly higher in neonates with nosocomial infection than that in community-acquired infections, Stool changes as watery or egg soup-like stool are more frequency in community-acquired infections (P<0.05),the difference was statistically significant.【Conclusions】1.Rotavirus is the major cause of nosocomial infection in neonatal. The prevalence rotavirus strain infecting neonates in ZheJiang,2009 is G3P[8] type, other virus strains were not detected;2.Rotavirus infection may cause changes in the composition of intestinal flora;3.The severity of the clinical manifestations in neonate after rotavirus infection is related to the age of infection and feeding patterns while independent of other factors;4.Hospital acquired rotavirus infection and community-acquired rotavirus infection in neonates have different clinical feature;5.Rotavirus infection in newborns can be detected throughout the year, was sporadic or epidemic, the peak season of nosocomial infections are Autumn and Winter, from October to December and January to March.