Molecular epidemiological analysis of Norovirus in patients with foodborne diseases in sentinel hospital, Ma'anshan City, Anhui Province

Abstract

Objective: To understand the infection status and genetic characteristics of Norovirus from foodborne diseases in sentinel hospital of Ma'anshan city. Methods: The 911 stool samples and epidemiological data of the patients with foodborne disease were collected from three hospitals of Ma'anshan city during January 2015 to June 2018. The G Ⅰ and G Ⅱ Norovirus were detected by real-time reverse transcription PCR. Some of the positive specimens were amplified by conventional reverse transcription PCR, and the PCR products were sequenced for sequence alignment and phylogenetic analysis. Results: The positive rate of Norovirus was 14.7% (134/911), in which 7 strains were G Ⅰ, 124 strains were G Ⅱ and 3 strains were mixed infection. Norovirus can be detected throughout the year, with high positive rate from December to April of the next year [24.4%(20/82)-45.3%(24/53)]. The 78 males (15.5%) and 55 females (13.7%) were positive for Norovirus (χ(2)=0.58,P=0.448). There was no significant difference in different age groups (χ(2)=9.55, P=0.089). A total of 79 strains were successfully sequenced, 4 strains were G Ⅰ group(5.1%), 75 strains were G Ⅱ group (94.9%). The predominant strains were GⅡ.17 and GⅡ.4, aud the number were 35 and 15 respectively. The predominant strains were different in different years. The main strain was GⅡ.17 in 2015 (30, 68.2%),GⅡ.4 in 2016 (5/9) and 2017 (8/16), but GⅡ.3 in 2018 (3/6). Conclusion: Norovirus diarrhea was popular in Ma'anshan city throughout the year,especially in winter and spring. The prevalent strain was GⅡ,genotypes were diversified distribution,the dominant strains were GⅡ.17 and GⅡ.4. The predominant strains were different in different years.