Etiological Study Of Viral Diarrhea Among Children In Lanzhou

Objective: Acute gastroenteritis is common health problem in children worldwide. It has been confirmed that socio-economic improvements in water and sanitation may not significantly reduce the incidence of viral diarrhea. Furthermore, it was absent specific medicine in clinic. We study molecular epidemiology of four major etiological viruses among children with acute diarrhea in Lanzhou, Gansu province China from July2004 through June2005. Our purpose is to accumulate datum for prevent and control Viral Diarrhea among Children in the region and to provide proof for develop correlate vaccine also.Methods: Stool specimens were collected from all inpatients less than 5 years old with acute diarrhea admitted in Department of Pediatrics, the First Hospital, Lanzhou University from July2004 through June2005. Dako IDEIA? kits were used for detection of rotavirus, adenovirus and astrovirus, and calicivirus detection by both reverse transcription-polymerase chain reactions (RT-PCR) and Enzyme-linked immunosorbant assay (ELISA). Further strain characterization of rotavirus and astrovirus were done with RT-PCR. Some PCR amplicons of calicivirus and astrovirus were cloned and sequenced. Phylogenetic tree was constructed for strain characterization.Results: A total of 400 stool samples were collected and tested. Rotavirus was present in 47.3% of cases, calicivirus in 15.5%, astrovirus in 9.5% and adenoviruses in 7.3%. Mixed infections with multiple enteric viruses were present in 13.5 % of all samples. Among 189 rotavirus positives, serotype G2 (34.4%) was the predominant strain followed by G3 (32.8%), Gl(l.l%) and mixed-G infection (5.8%). 25.9% of strains remained to be non-typeable. P genotyping showed P[4](45%) was most common followed by P[8](22.1%), and non-typeable was 32.9%. Strain P[4]G2 (43.6%) was the most common combination followed by P[8]G3 (25.6%), P [4]G3(13.8%), and P[8]G2, P[4]G1 and P[8)G1 were also identified. Among 38 astrovirus strains serotypes 1 (57.8%) was the predominant serotype. Serotype 3 and 8 were found only in one case, respectively. 14 strains remained to be non-typeable. Of 31 HuCV strains that were cloned and sequenced, 17 belonged to norovims genotype Gil- 4, 6 was norovirus genotype GII-3, and 1 was norovirus genotype GII-7, 4 belong to one sapovirus Gil cluster, SG-II-a. A peak admission of rotavirus diarrhea was observed between October to December. More than 95.0% of viral diarrhea hospitalization occurred among children aged <2 years. The incidence rates of rotavirus were highest in infants aged 6-23 months.Conclusion: Among viral pathogens of viral diarrhea hospitalizations among children in Lanzhou RV was the most important. The predominant strain circulated was P[4]G2 that was different from that before. GII-4 HuCVs and AstV strains serotypes 1 were the prevalent strains circulating in Lanzhou. The high rate of mixed infection with different viral agents was notable.