Evidence-Based interventions of Norovirus outbreaks in China

Abstract

BackgroundIn resource-limited settings where laboratory capacity is limited and response strategy is non-specific, delayed or inappropriate intervention against outbreaks of Norovirus (NoV) are common. Here we report interventions of two norovirus outbreaks, which highlight the importance of evidence-based modeling and assessment to identify infection sources and formulate effective response strategies.MethodsSpatiotemporal scanning, mathematical and random walk modeling predicted the modes of transmission in the two incidents, which were supported by laboratory results and intervention outcomes.ResultsSimulation results indicated that contaminated water was 14 to 500 fold more infectious than infected individuals. Asymptomatic individuals were not effective transmitters. School closure for up to a week still could not contain the outbreak unless the duration was extended to 10 or more days. The total attack rates (TARs) for waterborne NoV outbreaks reported in China (n = 3, median = 4.37) were significantly (p < 0.05) lower than worldwide (n = 14, median = 41.34). The low TARs are likely due to the high number of the affected population.ConclusionsWe found that school closure alone could not contain Norovirus outbreaks. Overlooked personal hygiene may serve as a hotbed for infectious disease transmission. Our results reveal that evidence-based investigations can facilitate timely interventions of Norovirus transmission.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-016-3716-3) contains supplementary material, which is available to authorized users.

Epidemiological characteristics and transmissibility of shigellosis in Hubei Province, China, 2005 – 2017

“…In this study, two models were developed according to the transmission routes of the disease. According to our previous research [14,19], we firstly built a susceptible-exposed-symptomatic-asymptomatic-recovered-water/food (SEIARW) model (denoted as Model 1) in which two routes (person-to-person and reservoir-to-person) were considered. For the route of person-to-person, two routes (symptomatic-to-susceptible and asymptomatic-to-susceptible) were both considered.…”

“…was employed for model simulation and least root mean square was adopted to assess the goodness of fit. The simulation methods were the same as the previously publications [12,14,19,30,31]. The chi-square and trend chi-square tests and t test were performed by SPSS 13.0 (IBM Corp., Armonk, NY, USA).…”

“…Our results showed that the mean value of R eff of Shigellosis was 1.19, meaning that the expected number of secondary infections that resulted from introducing a single infected individual into an otherwise susceptible population was only 1.19 on average. This revealed that the transmissibility of shigellosis is lower than many other infectious diseases such as influenza, Ebola virus disease, and Norovirus infection [12,14,15,34].…”

“…The ordinary differential equation model has a strong applicability. It could be used in different populations including school or community with small-scale outbreaks [14,19], and in different diseases such as shigellosis, norovirus infection, Ebola virus disease, and influenza [12,14,19,31].…”

“…The transmissibility of an infectious disease is commonly quantified by basic reproduction number (R 0 ), which is defined as the expected number of secondary infections that result from introducing a single infected individual into an otherwise susceptible population [12][13][14][15]. However, because of the disease intervention or the decreasing proportion of susceptible individuals due to the spread of the pathogen, it is hard to estimate R 0 .…”