Sequential Gastroenteritis Episodes Caused by 2 Norovirus Genotypes

We investigated sequential episodes of acute norovirus gastroenteritis in a young child within an 11-month period. The infections were caused by 2 distinct genotypes (GII.4 and GII.6). Failure to achieve cross-protective immunity was linked to absence of an enduring and cross-reactive mucosal immune response, a critical consideration for vaccine design.     

Genetic diversity of norovirus in hospitalised diarrhoeic children and asymptomatic controls in Dar es Salaam,Tanzania

This study investigated and reports norovirus diarrhoea, genetic diversity and associated clinical symptoms, HIV status and seasonality in a paediatric population of Tanzania.Stool specimens and demographic/clinical information, were prospectively collected from 705 hospitalised children with diarrhoea (cases) and 561 children without diarrhoea (controls) between 2010 and 2011. Norovirus detection was done by real-time RT-PCR. Genotype was determined using Gel-based and real time RT-PCR methods and sequencing targeting the polymerase and the capsid region respectively. Norovirus was detected in 14.3%, 181/1266 children. The prevalence of norovirus was significantly higher in cases (18.3%, 129/705) than in controls, (9.2%, 52/561), P < 0.05. Except for one child who had double infection with GI and GII all 129 cases had GII. Among controls, 23.1% had GI and 76.9% had GII. Norovirus GII.4 was significantly more prevalent in cases 87.9% than in controls 56.5%. Other genotypes detected in both cases and controls were GII.21, GII.16 and GII.g. The highest numbers of norovirus were detected in April 2011. The number of norovirus detected was significantly higher during the first than second year of life (109/540, 20.2% vs. 20/165, 12.1%). The prevalence of norovirus in HIV-positive and negative children was (21.2%, 7/33) and (10.3%, 40/390, P = 0.05) respectively, regardless of diarrhoea symptoms. No significant difference in gender, parent’s level of education or nutritional status with norovirus infection was observed within cases or controls. This study confirms the significant role of norovirus infection, especially GII.4 in diarrhoeic children who need hospitalisation and adds knowledge on norovirus epidemiology in the African region.     

Noroviren – ein Impfstoff muss erst entwickelt werden

After the first scientific documentation of a ‚winter vomiting disease‘-outbreak in Norwalk, Ohio and the detection of the causal agent many studies have been performed to establish effective preventive measures against Noro-Virus-infection. In 2010 first results of a successful vaccine trial using virus-like-particles were presented, followed by another vaccine-development in 2012. In this communication data on properties of Noroviruses and results of vaccine trials are presented.     

Human norovirus infection in Latin America

Noroviruses are important enteric pathogens involved in non-bacterial gastroenteritis outbreaks worldwide. Noroviruses mainly occur from person to person via the fecal-oral route but also through contaminated food or water; indirect contamination is also possible due to the resistance of the virus in the environment. Latin American countries as a whole cover a vast North-to-South range, which is highly heterogeneous in terms of climate, ecosystem, human population distribution (urban areas with high human densities versus closed communities), economic development and genetic backgrounds resulting from each particular historical context. This review aims to present epidemiological and clinical patterns of human norovirus infections in Latin American countries. Divergent prevalences were observed depending on the country and the surveyed population. In particular, a shift in rotavirus/norovirus ratio in the etiologies of gastroenteritis was detected in some countries and could be attributed partly to rotavirus vaccine coverage in their infant population. While GII.4 noroviruses were seen to constitute the most common genotype, differences in genotype distribution were observed both in the environment (via sewage sampling proxy) and between genotypes circulating in healthy and diarrheic patients. Due to high climatic discrepancies, different patterns of seasonality were observed. Accordingly, this continent may condense the different particular epidemiological features encountered for HuNoV infections worldwide.     

Lactoferrin for prevention of common viral infections

Although lactoferrin has many biological functions, the host-protective effects against pathogenic microorganisms including bacteria, fungi, and viruses are regarded as one of the most important. Here, we review research on the protective role of lactoferrin administration against common viral infections. Many studies have shown the in vitro antiviral activity of lactoferrin against viral pathogens that cause common infections such as the common cold, influenza, gastroenteritis, summer cold, and herpes, where lactoferrin inhibits mainly viral attachment to the target cells. Recently, studies indicating the in vivo protective effects of lactoferrin by oral administration against common viral infections have been increasing. For instance, norovirus is an extremely important emerging human pathogen that causes a majority of gastroenteritis outbreaks worldwide that may be a target candidate for lactoferrin. Lactoferrin consumption reduced the incidence of noroviral gastroenteritis in children and a similar effect was observed in a wide range of ages in a preliminary survey. A recent in vitro study reported that lactoferrin inhibits both cellular attachment of the murine norovirus, a virus closely-related to the human norovirus, and viral replication in the cells by inducing antiviral cytokines interferon (IFN)-α/β. Lactoferrin administration also enhances NK cell activity and Th1 cytokine responses, which lead to protection against viral infections. In conclusion, lactoferrin consumption may protect the host from viral infections through inhibiting the attachment of a virus to the cells, replication of the virus in the cells, and enhancement of systemic immune functions.     

Evaluation of the RIDAGENE real-time PCR assay for the detection of GI and GII norovirus

The current study examined the efficacy of the RIDAGENE norovirus (NoV) real-time polymerase chain reaction assay (R-Biopharm, Darmstadt, Germany) for use in a routine diagnostic laboratory. The RIDAGENE assay had an overall sensitivity of 98% but was more sensitive for GII than GI NoV. The assay had a specificity of 98%. The RIDAGENE assay could detect a variety of GI and GII open reading frame 2 genotypes including GI.1, GI.3, GI.8, GI.13, GII.2, GII.3, GII.4 (including the following variants: 2006b, 2009, 2012, and 3 others that have not been assigned), GII.6, GII.12, and GII.13. The assay did not cross react with a number of gastroenteritis viruses including adenovirus, astrovirus, rotavirus, and sapovirus. The assay was straightforward to perform, and for a run of 50 specimens, a result was obtainable in roughly 4 hours. The RIDAGENE assay can be recommended as a valuable detection method for NoV.     

Norovirus prevalence and estimated viral load in symptomatic and asymptomatic children from rural communities of Vhembe district,South Africa

BackgroundHuman Norovirus (NoV) is recognized as a major etiological agent of sporadic acute gastroenteritis worldwide.ObjectivesThis study describes the clinical features associated with Human NoV occurrence in children and determines the prevalence and estimated viral burden of NoV in symptomatic and asymptomatic children in rural South Africa.Study designBetween July 2014 and April 2015, outpatient children under 5 years of age from rural communities of Vhembe district, South Africa, were enrolled for the study. A total of 303 stool specimens were collected from those with diarrhea (n = 253) and without (n = 50) diarrhea. NoVs were identified using real-time one-step RT-PCR.ResultsOne hundred and four (41.1%) NoVs were detected (62[59.6%] GII, 16[15.4%] GI, and 26[25%] mixed GI/GII) in cases and 18 (36%) including 9(50%) GII, 2(11.1%) GI and 7(38.9%) mixed GI/GII in controls. NoV detection rates in symptomatic and asymptomatic children (OR = 1.24; 95% CI 0.66⿿2.33) were not significantly different. Comparison of the median C_T values for NoV in symptomatic and asymptomatic children revealed significant statistical difference of estimated GII viral load from both groups, with a much higher viral burden in symptomatic children.ConclusionsThough not proven predictive of diarrhea disease in this study, the high detection rate of NoV reflects the substantial exposure of children from rural communities to enteric pathogens possibly due to poor sanitation and hygiene practices. The results suggest that the difference between asymptomatic and symptomatic children with NoV may be at the level of the viral load of NoV genogroups involved.     

Acute norovirus gastroenteritis in children in a highly rotavirus-vaccinated population in Northeast Brazil

BackgroundGastroenteritis is one of the most important causes of morbidity and mortality in children and an important etiological agent is norovirus.ObjectiveWe describe the occurrence and characteristics of norovirus diarrhoea in children from Sergipe, Northeast-Brazil, over two consecutive periods of three years following rotavirus vaccine introduction.Study designA cross sectional hospital-based survey conducted from October-2006 to September-2009 and from July-2011 to January-2013. Acute diarrhoea cases had a stool sample collected and tested for norovirus by RT-PCR and positive samples were sequenced.ResultsIn total 280 (19.6%) of 1432 samples were norovirus positive, including 204 (18.3%) of 1113 samples collected during the first period and 76 (23.9%) of 318 collected during the second period. The proportion of children with norovirus infection increased significantly through the second study period (χ² for trend = 6.7; p = 0.009), was more frequent in rotavirus vaccinated and in younger children (p < 0.001). Of 280 norovirus-positive specimens, 188 (67.1%) were sequenced. Of these, 12 were genogroup I and 176 genogroup II. The main genotype was GII.4 (149/188, 79.3%), followed by GII.2 (6, 3.2%) and GII.6 (5, 2.6%).ConclusionNorovirus annual detection rates increased over the study period. The detection of norovirus was higher among young children.     

2000-2013年我国诺如病毒感染性胃肠炎暴发流行病学特征分析

目的 了解我国诺如病毒的流行病学特征及变化趋势,为制定有效的防控措施提供依据。方法 以诺如病毒、诺瓦克样病毒以及暴发、调查为关键词检索,收集整理2000-2013年在CNKI、万方和维普等中文数据库中的文献并进行分析。结果 共收集符合要求的文献52篇,涉及诺如病毒暴发疫情72起,累计报道病例11 778例,平均164例/起,疫情持续时间平均8.57 d。报道疫情数居前3位的省份依次是广东省28起（占38.89%）,浙江省18起（占25.00%）,广西壮族自治区6起（占8.33%）。暴发场所以学校及托幼机构为主,有53起,占73.61%,其中中学25起、小学及幼儿园17起,大学11起;其次是养老/医疗机构10起,占13.89%。传播途径以经水传播为主,有27起,占37.50%,人-人接触传播24起,占33.33%,食源性传播17起,占23.61%。不同场所疫情传播途径差异有统计学意义（2=48.899,P=0.000）。在经水传播的疫情中,由桶装水污染引起的暴发最多,占48.15%。基因组别分布GⅡ24起,占72.73%,GⅠ6起,占18.18%。结论 需加强关注我国诺如病毒感染性胃肠炎暴发,特别是学校和幼托机构等人群聚集的场所。建议加强高危场所管理和水质监测,提高菌株检测鉴定水平。