Utility of Droplet Digital PCR Assay for Quantitative Detection of Norovirus in Shellfish, from Production to Consumption in Guangxi, China

Objective Shellfish are recognized as important vehicles of norovirus-associated gastroenteritis. The present study aimed to monitor norovirus contamination in oysters along the farm-to-fork continuum in Guangxi, a major oyster production area in Southwestern China. Methods Oyster samples were collected monthly from farms, markets, and restaurants, from January to December 2016. Norovirus was detected and quantified by one-step reverse transcription-droplet digital polymerase chain reaction（RT-ddPCR）. Results A total of 480 oyster samples were collected and tested for norovirus genogroups I and II. Norovirus was detected in 20.7% of samples, with genogroup II predominating. No significant difference was observed in norovirus prevalence among different sampling sites. The norovirus levels varied widely, with a geometric mean of 19,300 copies/g in digestive glands. Both norovirus prevalence and viral loads showed obvious seasonality, with a strong winter bias. Conclusion This study provides a systematic analysis of norovirus contamination ‘from the farm to the fork＇ in Guangxi. RT-ddPCR can be a useful tool for detection and quantification of low amounts of norovirus in the presence of inhibitors found particularly in foodstuffs. This approach will contribute to the development of strategies for controlling and reducing the risk of human illness resulting from shellfish consumption.

An outbreak of human astrovirus lineage 1b in a middle school in Guangxi, Southern China in 2017

To the Editor: Human astroviruses (HAstVs) are important etiologic agents of viral gastroenteritis worldwide,[1,2] especially in pediatric patients aged ≤5 years.[3] However, reports on HAstV outbreaks in middle schools remain limited. Here, we report a HAstV outbreak in a middle school in China. Clinical and environmental samples tested positive for HAstV, showing a 100% nucleotide identity of the 348-bp region of the capsid protein gene.

Schistosomiasis Surveillance--China,2015−2018

Background The prevalence of schistosomiasis in China is at the lowest level in history,and sentinel surveillance sites of schistosomiasis have fully covered all epidemic areas of China.This article has analyzed the surveillance data for the last four years and can help guide the next stage of surveillance work at the national level,including the scope of surveillance,surveillance content,and surveillance methods,etc.Methods Data from the National Schistosomiasis Surveillance System were collected.The infection rate of schistosomiasis among the human population,livestock,snails,and the change of the breeding area of snails in sentinel surveillance sites for four consecutive years were analyzed,and the trends in schistosomiasis prevalence in surveillance sites were determined.Results The prevalence of schistosomiasis in all sentinel surveillance sites of China showed downward trends from 2015 to 2018 with infection rates decreasing in this time period for local human population(0.05%to 0.00%),the floating population(0.020% to 0.003%),and cattle(0.037% to 0.000%).No infected snails were found during the period.From 2015 to 2018,the total area of newly found habitats of snails(Oncomelania hupensis,O.hupensis)were 34,730 m^(2),1,367,694 m^(2),18,944 m^(2),and 50,420 m^(2),and the total area of re-emergent habitats of snails(O.hupensis)were 822,194 m^(2),1,391,779 m^(2),1,516,292 m^(2),and 1,750,558 m^(2),respectively.Conclusions and Implications for Public Health Practice The prevalence of schistosomiasis in human and livestock is going down and is sustained at a very low level,but new and re-emerging habitats of O.hupensis are new challenges regardless of the achievement of schistosomiasis control.Therefore,two actions are necessary to effectively further reduce the transmission risk of schistosomiasis:1)taking effective measures to control the source of infection of schistosomiasis;and 2)reducing the breeding areas of O.hupensis.