Epidemiology and genetic characteristics of norovirus among sporadic cases of adult diarrhear in Jilin province, 2015

Objective To understand the epidemiological and genetic characteristics of norovirus among sporadic cases of adult diarrhea in Jilin province. Methods Fecal samples were collected from diarrheal patients in 2015. Fluorscent quantitative PCR and RT-PCR were used to amplify the fragment of polymerase gene and complete VP1. Phylogenetic tree was constructed based on sequencing results and was used for analyses of neucleotide and amino acid mutations. Results A total of 619 samples were analyzed. Thirty-eight samples were positive by fluorscent quantitative PCR with an overall positive rate of 6.14%. Positive infection rates peaked in December and January. The positive rate was more than 12% among old people of over 80 years old. Four complete VP1 sequences of GII.P17_GII.17 were obtained, with the same genotype and high similarities to the strains responsible for epidemics in Guangdong province and Jiangsu province during 2014-2015. Genotyping results by viral polymerase gene and by VP1 were the same. Conclusions In Jilin province, norovirus infections among diarrhea cases occurred frequently in winter. Old people of over 80 years old were mainly affected. This is the first time to detect GII.P17_GII.17 strain in sporadic cases of adult diarrhea in Jilin province. Key words: Adult; Norovirus; Genotype; Epidemiology