Control Of Norovirus Infection Research Articles

Spatiotemporal distribution of norovirus infection outbreaks in Chengdu

Objective To analyze the spatiotemporal distribution of norovirus infection outbreaks in Chengdu with the geographic information system (GIS) and provide evidence for the prevention and control of norovirus infection. Methods A database of the outbreaks of norovirus infection in Chengdu from 2014 to 2019 was established. The concentration ratio and circular distribution method were used to analyze the temporal clustering of the epidemic, and the Moran’s Ⅰ method was used to analyze spatial autocorrelation. Results The M value of norovirus outbreaks in Chengdu was 0.3927872, which showed the temporal clustering of norovirus infection with higher incidence in winter and the incidence peak during November - March. The incidence was higher in central urban area than in suburban area, with different “hot spot” or “cold spot” in different seasons. Conclusion There was obvious spatiotemporal clustering of norovirus infection outbreaks in Chengdu, suggesting that the prevention and control of norovirus infection should be strengthened in key area and period.

Control of Norovirus Infection

Control of Norovirus Infection

Surveillance of the 'bud event of norovirus-associated gastroenteritis' in schools: does it work in the prevention of norovirus infection outbreaks in Shanghai?

Outbreaks of norovirus-associated gastroenteritis have been reported in schools in recent decades in China. For early warning and response to infectious disease outbreaks, the Shanghai Infectious Diseases Bud Event Surveillance System (IDBESS) was established in 2016. Bud event is a term used for the early sign of a potential infectious disease outbreak in public settings when the first few cases appear. This study aimed to describe the epidemiological characteristics of Norovirus-associated gastroenteritis bud events from June 2016 to December 2017 and to understand factors influencing the severity of events. Data were extracted from the IDBESS, supplemented by field investigations and school absence surveillance. In total, 189 bud events of Norovirus-associated gastroenteritis were reported in schools and kindergartens, affecting 3827 individuals and 52.38% happened in primary schools. The attack rate of Norovirus-associated gastroenteritis was 3.82% on average in students in the affected schools. In each event, case numbers varied between 5 and 148, with a median of 16. The duration of bud events lasted for 2 days on average. School absence happened in 47.93% (1797/3749) of affected students and the average duration of absence was 3.07 days. It was found that a longer delay before reporting was associated with a longer-lasting duration of bud event (OR = 2.25, 95% CI: 1.65, 3.07). In conclusion, ascribed to the sensitive threshold for alerting and the timely field investigation, the surveillance of bud events of Norovirus-associated gastroenteritis is effective in the control of Norovirus infection among preschool children and students in Shanghai.

Control of norovirus infection.

The purpose of the review is to provide an update on control measures for norovirus (NoV), which is the most commonly implicated pathogen in acute gastroenteritis and outbreaks, causing major disruption in nurseries, schools, hospitals and care homes. Important developments include the discovery that virus particles, previously considered to be the infectious unit, also occur in clusters, which appear to be more virulent than individual virus particles; a working culture system using human stem-cell derived enteroids; promising results from early phase clinical trials of candidate NoV vaccines, which appear to be safe and immunogenic; chronic NoV affects patients with primary and secondary immune deficiencies. Although several treatments have been used none are supported by well designed clinical trials; infection control procedures are effective if properly implemented. NoV remains an important cause of morbidity and mortality. Although there are exciting developments on the vaccine front, the mainstay of control remains good hand hygiene, adherence to infection control procedures and limiting contamination of food, water and the wider environment. Once vaccines are available there will be important decisions to be made about how best to implement them.

Analysis on risk factors for norovirus outbreaks in Guangdong province, 2008-2015

Objective: To analyze transmission factors of norovirus outbreaks in Guangdong province during 2008-2015 and provide evidence for the prevention and control of norovirus infection. Methods: Epidemiological analysis was performed on the data of norovirus outbreaks reported in Guangdong from January 1, 2008 to December 31, 2015, which were obtained from the Public Health Emergency Management Information System of Guangdong province. The samples collected from the norovirus outbreaks were detected for norovirus by RT-PCR and the gene sequencing of the positive PCR products were performed. Results: A total of 96 norovirus outbreaks were reported in Guangdong during 2008-2015. Sixteen outbreaks were reported during 2008-2012 and 80 outbreaks were reported during 2013-2015 (83.3%). Eighty-two outbreaks (85.4%) occurred in schools. The infection routes included foodborne transmission in 39 outbreaks (40.6%), person to person transmission in 23 outbreaks (24.0%) and waterborne transmission in 8 outbreaks (7.3%). The gene sequencing results showed that variant GⅡ.4/Sydney2012 was the predominant pathogen for 6 of the 20 outbreaks (30.0%) during 2012-2013. Variant GⅡ.17 was the predominant pathogens for 33 of the 53 outbreaks (62.3%) during 2014-2015. Conclusion: The norovirus outbreaks in Guangdong during 2008-2015 were caused by foodborne and person to person transmissions of two emerging variant: GⅡ.4/Sydney2012 and GⅡ.17.

Guidelines on outbreak investigation, prevention and control of norovirus infection (2015)

Guidelines on outbreak investigation, prevention and control of norovirus infection (2015)

Multicenter evaluation of RIDA Gene Norovirus GI/GII assay for the detection of norovirus from stool specimens

Noroviruses are the primary cause of acute nonbacterial gastroenteritis in humans and are responsible for nearly half of gastroenteritis cases globally. The norovirus strain variants have been circulating in underdeveloped regions in western China, where pediatric diarrhea acts as the major public health concern. The study aims to identify the epidemic genotypes of norovirus and explore their genetic characteristics in Chongqing, China. By performing a hospital-based surveillance from 2010 to 2013, we identified a significant shift of the predominant Norovirus strains in recent 4 years in the studied area. The GII.4_Sydney_2012 and GII.12/GII.3 strains replaced GII.4_2006b and GII.4_NewOrleans_2009 to become the predominant genotypes, with the proportion of ORF1/ORF2 recombinants rising steadily from 2010 to 2013. A new GII.12/GII.3 variant that was seldom detected became a predominant genotype during the study course. Several distinct genotypes of norovirus, including GII.16/GII.2, GII.21/GII.3, GII.15 and GII.6, were also detected. The rising circulation of recombination in Chongqing illustrated the significance of recombination, especially in the ORF1/ORF2 overlap region, in the evolution and epidemic of norovirus. The epidemic of GII.12/GII.3 in Chongqing also serves as a reminder that prolonged surveillance is warranted for better prevention and control of norovirus infection.

An increasing prevalence of recombinant GII norovirus in pediatric patients with diarrhea during 2010–2013 in China

Noroviruses are the primary cause of acute nonbacterial gastroenteritis in humans and are responsible for nearly half of gastroenteritis cases globally. The norovirus strain variants have been circulating in underdeveloped regions in western China, where pediatric diarrhea acts as the major public health concern. The study aims to identify the epidemic genotypes of norovirus and explore their genetic characteristics in Chongqing, China. By performing a hospital-based surveillance from 2010 to 2013, we identified a significant shift of the predominant Norovirus strains in recent 4years in the studied area. The GII.4_Sydney_2012 and GII.12/GII.3 strains replaced GII.4_2006b and GII.4_NewOrleans_2009 to become the predominant genotypes, with the proportion of ORF1/ORF2 recombinants rising steadily from 2010 to 2013. A new GII.12/GII.3 variant that was seldom detected became a predominant genotype during the study course. Several distinct genotypes of norovirus, including GII.16/GII.2, GII.21/GII.3, GII.15 and GII.6, were also detected. The rising circulation of recombination in Chongqing illustrated the significance of recombination, especially in the ORF1/ORF2 overlap region, in the evolution and epidemic of norovirus. The epidemic of GII.12/GII.3 in Chongqing also serves as a reminder that prolonged surveillance is warranted for better prevention and control of norovirus infection.

Critical Role for Interferon Regulatory Factor 3 (IRF-3) and IRF-7 in Type I Interferon-Mediated Control of Murine Norovirus Replication

Human noroviruses (HuNoV) are the major cause of epidemic, nonbacterial gastroenteritis in the world. The short course of HuNoV-induced symptoms has implicated innate immunity in control of norovirus (NoV) infection. Studies using murine norovirus (MNV) confirm the importance of innate immune responses during NoV infection. Type I alpha and beta interferons (IFN-α/β) limit HuNoV replicon function, restrict MNV replication in cultured cells, and control MNV replication in vivo. Therefore, the cell types and transcription factors involved in antiviral immune responses and IFN-α/β-mediated control of NoV infection are important to define. We used mice with floxed alleles of the IFNAR1 chain of the IFN-α/β receptor to identify cells expressing lysozyme M or CD11c as cells that respond to IFN-α/β to restrict MNV replication in vivo. Furthermore, we show that the transcription factors IRF-3 and IRF-7 work in concert to initiate unique and overlapping antiviral responses to restrict MNV replication in vivo. IRF-3 and IRF-7 restrict MNV replication in both cultured macrophages and dendritic cells, are required for induction of IFN-α/β in macrophages but not dendritic cells, and are dispensable for the antiviral effects of IFN-α/β that block MNV replication. These studies suggest that expression of the IFN-α/β receptor on macrophages/neutrophils and dendritic cells, as well as of IRF-3 and IRF-7, is critical for innate immune responses to NoV infection.

Essential Cell-Autonomous Role for Interferon (IFN) Regulatory Factor 1 in IFN-γ-Mediated Inhibition of Norovirus Replication in Macrophages

Noroviruses (NVs) cause the majority of cases of epidemic nonbacterial gastroenteritis worldwide and contribute to endemic enteric disease. However, the molecular mechanisms responsible for immune control of their replication are not completely understood. Here we report that the transcription factor interferon regulatory factor 1 (IRF-1) is required for control of murine NV (MNV) replication and pathogenesis in vivo. This led us to studies documenting a cell-autonomous role for IRF-1 in gamma interferon (IFN-γ)-mediated inhibition of MNV replication in primary macrophages. This role of IRF-1 in the inhibition of MNV replication by IFN-γ is independent of IFN-αβ signaling. While the signal transducer and activator of transcription STAT-1 was also required for IFN-γ-mediated inhibition of MNV replication in vitro, class II transactivator (CIITA), interferon regulatory factor 3 (IRF-3), and interferon regulatory factor 7 (IRF-7) were not required. We therefore hypothesized that there must be a subset of IFN-stimulated genes (ISGs) regulated by IFN-γ in a manner dependent only on STAT-1 and IRF-1. Analysis of transcriptional profiles of macrophages lacking various transcription factors confirmed this hypothesis. These studies identify a key role for IRF-1 in IFN-γ-dependent control of norovirus infection in mice and macrophages.