Etiological study of enteric viruses and the genetic diversity of norovirus, sapovirus, adenovirus, and astrovirus in children with diarrhea in Chongqing, China

Background: Enteric viruses are a major cause of diarrhea in children, especially those < 5 years old. Identifying the viral agents is critical to the development of effective preventive measures. This study aimed to determine the prevalence of common enteric viruses in children < 5 years old presented with diarrhea to the Children's Hospital of Chongqing Medical University. Methods: Five hundred fecal samples were collected between August and November 2010 from children < 5 years of age who presented with acute diarrhea at the Children's Hospital of Chongqing Medical University. All samples were tested for rotaviruses A, B, and C, noroviruses GI and GII, adenovirus, sapovirus, and astrovirus using enzyme-linked immunosorbent assay, reverse transcription-polymerase chain reaction (RT-PCR), or PCR. Partial sequences of norovirus, sapovirus, adenovirus, and astrovirus were phylogenetically analyzed to determine the genotype. Results: Enteric viruses were detected in 302 of the 500 children who presented with acute diarrhea (277/477; 58.07%) and persistent diarrhea (5/23; 21.74%). In 277 samples from children with acute diarrhea in whom at least one viral agent was found, rotavirus A was the most frequent virus identified (132 cases; 27.67%), followed by norovirus GII in 130 cases (27.25%), adenovirus in 30 cases (6.29%), sapovirus in 9 cases (1.89%) and astrovirus in one case (0.21%). Twenty-two of the norovirus GII-positive cases were randomly selected for genotyping. GII/4 was the predominant strain, followed by GII/6, GII/2, GII/3, and GII/7. Sapovirus was classified into four genotypes: GI/1 was predominant, followed by GI/2, GII/1, and GIV. The predominant adenovirus was type 41. Mixed infections were found in 25 cases, all of which presented with acute diarrhea (25/477; 5.24%). Viruses were positive in 5/23 (21.74%) cases with persistent diarrhea. Neither rotavirus B, rotavirus C, nor norovirus GI were found in any of the samples. Conclusions: Enteric viruses are a major cause of diarrhea in children < 5 years old in Chongqing. Rotavirus A is the most common etiological agent, follow by norovirus.