Norovirus Outbreak in Iran

Outbreaks of gastroenteritis are a major public health problem in New Zealand. The introduction of molecular detection methods has now shown that the 'Norwalk-like viruses' (NLVs) are the major cause of food and waterborne nonbacterial gastroenteritis. Reverse transcription and polymerase chain reaction (RT-PCR) were used to determine the presence of NLVs in faecal specimens from 83 nonbacterial gastroenteritis outbreaks occurring in New Zealand between August 1995 and July 1999. Further characterisation of the NLVs for epidemiological purposes was carried out by dot blot DNA hybridisation and DNA sequencing of representative outbreak strains. The majority of NLV strains occurring in New Zealand since August 1995 are similar to those occurring overseas. The predominant New Zealand strain is genetically similar to the Bristol/Lordsdale virus group. Several New Zealand outbreaks were attributed to Auckland virus, a Mexico-like NLV strain identified as the most likely cause of gastroenteritis after consumption of contaminated oysters in 1994. A new strain, designated Napier virus, has been identified in six outbreaks since 1996. A number of strains closely resembling internationally recognised strains, including Southampton virus, Saratoga virus; Desert Shield virus and Melksham virus have been associated with gastroenteritis outbreaks across New Zealand. Application of these typing methods has provided information on disease transmission for epidemiological investigations of public health significance.

Small round-structured viruses (SRSVs) or Norwalk-like viruses have been implicated as an important causative agent of gastroenteritis outbreaks. We used the relatively newly developed recombinant enzyme immunoassays (EIAs) to determine the seroprevalence of Norwalk virus (NV) and Mexico virus (MxV) in a family-based cohort and an antenatal clinic cohort at Ga-Rankuwa Hospital, Ga-Rankuwa, South Africa. High prevalences (96 to 99%) of anti-NV and anti-MxV antibodies were detected in both cohorts. We also investigated the pattern of antibody acquisition in a cohort of infants and young children without gastroenteritis and found that by 48 months of age all children had acquired adult antibody levels to both these viruses. Lastly, we tested 276 stool specimens collected from infants and young children with gastroenteritis for the presence of NV or MxV antigen by recombinant EIAs to each virus, by electron microscopy (EM), and by reverse transcription (RT)-PCR. NV and MxV antigens were present in 1.8 and 4.3% of the stool specimens, respectively, by the recombinant EIAs; 9.2% were positive for SRSVs by EM, and 25% of these SRSVs gave a positive result by RT-PCR for primer pair 35-36 directed to a region of the RNA-dependent RNA polymerase gene. The seroprevalence studies indicate a high level of exposure to these viruses in both children and adults. Although the viral antigens are not highly prevalent in diarrheal stools, it was determined by the two assays for NV and MxV that children are, nevertheless, infected early in life.

Background: Norovirus is now recognized as a major cause of gastroenteritis among children worldwide. This study aimed to determine the prevalence of Norovirus infection among children that are less than five years of age in Niger-Delta zone, Nigeria. Methods: A total of 263 subjects consisted of 163 children with diarrhea attending Paediat-ric clinics at the Central Hospital, Warri and Federal Medical Center, Yenagoa as well as 100 aged- and sex-matched healthy individuals that served as controls were recruited for this study. Demographic information was obtained through the aid of a well-structured questionnaires. Norovirus was detected by using a rapid lateral flow immunochromatographic assay kit (Biopanda reagents, Belfast, United Kingdom). Results: The overall prevalence of Norovirus infection was 15.3%. The prevalence of Norovirus infection was significantly higher in Delta State than in Bayelsa State (22.9 % vs. 6.7%; OR= 3.6615; 95% CI = 1.378, 9.725; P=0.0092). Children that are less than 5 years of age attending day care centers are greatly affected by Norovirus infection (P=0.0044). Also, poor hand hygiene practice was also a significant risk factor for Norovirus infection among study subjects (P=0.0036). Furthermore, secretors were found to have a 1 to 334 fold increased risk of acquiring Norovirus infection in Delta State than in Bayelsa State (OR=19.28, 95% C.I, 1.1102, 334.68, P=0.0422). Conclusion: The need for routine screening for Norovirus infection among children with diarrhea is advocated. Data from this study as well suggests that genetic and environmental factors play a role in Norovirus infection.

Considerable information has recently emerged regarding certain "groups" of novel viruses associated with gastroenteritis in humans. The viruses reviewed here are 20-35 nm in diameter and can be detected in the stools of acutely ill individuals with gastroenteritis. These viruses can be conveniently divided into four "groups": Norwalk-like agents, caliciviruses, astroviruses, and other small round viruses. The evidence for the etiologic association of these agents with gastroenteritis varies from agent to agent but is most extensive for the Norwalk-like agents, of which the Norwalk serotype is a major cause of epidemic gastroenteritis. Human caliciviruses appear to be relatively common causes of gastroenteritis in children, particularly in Japan and the United Kingdom. Astroviruses have been reported as occasional causes of gastroenteritis in children and adults in various parts of the world. The epidemiological significance of the other small round viruses is unknown. Because of the difficulty of cultivating these agents in vitro, biochemical and antigenic characterization of these agents is incomplete. An understanding of the pathogenesis of disease and of the roles of immune responses to infection is similarly at a primitive stage. The recent development of sensitive and efficient assays for detection of several of these agents and the reports that certain strains of human caliciviruses and astroviruses can be cultivated in vitro should facilitate characterization and epidemiological studies of these agents. Systematic, prospective epidemiological studies of these agents in well-defined populations of various age groups are sorely needed for definition of the relative importance of each agent in human disease. Such information is essential for the consideration of appropriate control measures.

Norovirus infections are among the major causes of acute gastroenteritis worldwide. In Germany, norovirus infections are the most frequently reported cause of gastroenteritis, although only laboratory confirmed cases are officially counted. The high infectivity and environmental persistence of norovirus, makes the virus a relevant pathogen for water related infections. In the 2017 guidelines for potable water reuse, the World Health Organization proposes Norovirus as a reference pathogen for viral pathogens for quantitative microbial risk assessment (QMRA). A challenge for QMRA is, that norovirus data are rarely available over long monitoring periods to assess inter-annual variability of the associated health risk, raising the question about the relevance of this source of variability regarding potential risk management alternatives. Moreover, norovirus infections show high prevalence during winter and early spring and lower incidence during summer. Therefore, our objective is to derive risk scenarios for assessing the potential relevance of the within and between year variability of norovirus concentrations in municipal wastewater for the assessment of health risks of fieldworkers, if treated wastewater is used for irrigation in agriculture. To this end, we use the correlation between norovirus influent concentration and reported epidemiological incidence (R²=0.93), found at a large city in Germany. Risk scenarios are subsequently derived from long-term reported epidemiological data, by applying a Bayesian regression approach. For assessing the practical relevance for wastewater reuse we apply the risk scenarios to different irrigation patterns under various treatment options, namely “status-quo” and “irrigation on demand”. While status-quo refers to an almost all-year irrigation, the latter assumes that irrigation only takes place during the vegetation period from May - September. Our results indicate that the log-difference of infection risks between scenarios may vary between 0.8 and 1.7 log given the same level of pre-treatment. They also indicate that under the same exposure scenario the between-year variability of norovirus infection risk may be > 1log, which makes it a relevant factor to consider in future QMRA studies and studies which aim at evaluating safe water reuse applications. The predictive power and wider use of epidemiological data as a suitable predictor variable should be further validated with paired multi-year data.

"Norwalk-like viruses" (NLVs) are a common cause of epidemic gastroenteritis in adults and children in developed countries. However, little is known about the role of NLVs in endemic pediatric gastroenteritis in developing countries. We sequenced Genogroup I and II NLV reverse transcription-polymerase chain reaction (RT-PCR) products from an 81-nucleotide region of the viral RNA polymerase gene to examine the molecular epidemiology of NLV infection in children younger than 5 years of age in Forteleza, Ceará, Brazil. NLV-positive PCR products were obtained from stool specimens collected over a 16-month period (1990-1991) from diarrhea cases and controls in a cohort of 120 children in an urban shantytown and from a study in the same city of hospitalized children with persistent diarrhea. Eight unique strains were detected in 15 specimens from 10 cohort children and in two hospital specimens. Nucleotide identity between the strains (5 Genogroup I, 3 Genogroup II) ranged from 63% to 88%. We designated these strains BraV1-8, for Brazil virus 1-8. The degree of genomic diversity of NLV strains we identified in this cohort during a short time period suggests multiple foci of infection within the community. Furthermore, sequence analysis of strains from two children with multiple symptomatic NLV infections indicates that infection with one strain was not protective against subsequent infection with a different strain in the same genogroup. These findings have implications for vaccine development and the prevention of pediatric gastroenteritis in developing countries.

Norovirus is the leading cause of epidemic and endemic acute gastroenteritis worldwide and the most frequent cause of foodborne illness in the United States. There is no specific treatment for norovirus infections and therapeutic interventions are based on alleviating symptoms and limiting viral transmission. The immune response to norovirus is not completely understood and mechanistic studies have been hindered by lack of a robust cell culture system. In recent years, the human intestinal enteroid/human intestinal organoid system (HIE/HIO) has enabled successful human norovirus replication. Cells derived from HIE have also successfully been subjected to genetic manipulation using viral vectors as well as CRISPR/Cas9 technology, thereby allowing studies to identify antiviral signaling pathways important in controlling norovirus infection. RNA sequencing using HIE cells has been used to investigate the transcriptional landscape during norovirus infection and to identify antiviral genes important in infection. Other cell culture platforms such as the microfluidics-based gut-on-chip technology in combination with the HIE/HIO system also have the potential to address fundamental questions on innate immunity to human norovirus. In this review, we highlight the recent advances in understanding the innate immune response to human norovirus infections in the HIE system, including the application of advanced molecular technologies that have become available in recent years such as the CRISPR/Cas9 and RNA sequencing, as well as the potential application of single cell transcriptomics, viral proteomics, and gut-on-a-chip technology to further elucidate innate immunity to norovirus.

Noroviruses are the most common cause of gastroenteritis in the United States. An understanding of the infectious dose of these viruses is important for risk assessment studies. Healthy adults were enrolled in a randomized, double-blind, placebo-controlled evaluation of different dosages of Norwalk virus. Eligible subjects were monitored for clinical gastroenteritis, and infection status was determined. The presence of virus in vomitus was also assessed. Fifty-seven persons were enrolled; 8 received placebo and an additional 8 persons were considered to be nonsusceptible on the basis of being secretor negative. Twenty-one persons were infected (all blood group O or A), and 67% of those infected developed viral gastroenteritis. The 50% human infectious dose was calculated to be 3.3 reverse transcription polymerase chain reaction units (approximately 1320 genomic equivalents [gEq]) for secretor-positive blood group O or A persons and 7.0 (approximately 2800 gEq) for all secretor-positive persons. The time of illness onset was inversely correlated with inoculum dose. The maximal concentration of virus shedding was higher for persons with gastroenteritis. Norwalk virus was identified in 15 of 27 (56%) vomitus samples at a median concentration of 41 000 gEq/mL. The 50% human infectious dose measured is higher than previous estimates and similar to that of other RNA viruses. Clinical Trials Registration NCT00138476.

Enteric viruses are the major cause of gastroenteritis and enteric hepatitis worldwide, but in some areas like Saudi Arabia, little is known about their presence in water sources. The available information from clinical samples is not enough to figure out their actual prevalence. The aim of this study was to gather information for the first time in Saudi Arabia on the presence of the Norovirus (NoV) genogroup GI and GII, hepatitis A virus (HAV), and hepatitis E virus (HEV) in water. For this purpose, thirteen monthly samples were collected from Lake Wadi Hanifa and surrounding wells from December 2014 to November 2015. Viruses were detected and quantified using real-time RT-qPCR. Despite HEV findings being anecdotic, our results highlight interesting behaviors of the other viruses. There was a higher prevalence of noroviruses in Wadi Hanifa samples than in well water samples (46.43% vs. 12.5% of NoV GI; 66.67% vs. 8.33% of NoV GII). On the contrary, similar levels of HAV positivity were observed (40.48% in surface water vs. 43.06% in well water). Also, a strong influence of flooding events on HAV and NoV GI occurrence was observed in both surface and well water samples, with NoV GII apparently not affected.

Introduction: Norovirus is a leading cause of food borne illness in the United States and causes symptoms of abdominal pain, vomiting, and diarrhea. In immunocompetent patients, norovirus is characteristically acute and self-limiting. We present an unusual case of norovirus gastroenteritis leading to markedly elevated transaminases, a connection that has seldom been reported in the literature. Case Description/Methods: A 24-year-old man with no significant past medical history presented with abdominal pain, vomiting, and jaundice one day after eating pork at a social event. He denied drug and alcohol use. He did not take any medications or supplements. Physical exam revealed jaundice and epigastric tenderness. Initial labs revealed an aspartate aminotransferase (AST) of 1205, alanine aminotransferase (ALT) of 2,170, alkaline phosphatase of 197, total bilirubin of 6.1, direct bilirubin of 4.43, international normalized ratio of 1.4, and albumin of 3.8. Hepatitis panel, acetaminophen level, alcohol level, urine drug screen, lipase, LKM-1, ceruloplasmin, AMA, ANA, ASMA, dsDNA, ferritin, IgG levels, EBV, CMV, and HSV were unremarkable. GI panel revealed a positive norovirus result. Gastroenterology was consulted, and recommended N-acetylcysteine for empiric management of the acute liver injury. Abdominal ultrasound and Computed tomography showed no acute process. MRCP showed findings consistent with acute hepatitis, mild splenomegaly, and mildly enlarged portal vein. Although the patient's symptoms resolved a few days into his hospitalization, his hepatic function testing worsened. Labs revealed a peak AST of 2597, ALT of 3541, total bilirubin of 34.1, and international normalized ratio of 2.2. This prompted the pursuit of a liver biopsy, which revealed acute liver injury favoring alcohol-related acute hepatitis. However, a PEth level obtained during hospitalization was negative. Thus, the patient's acute liver injury was attributed to norovirus. He was treated with corticosteroids with eventual improvement in his liver enzymes and discharged on day 19 of hospitalization. Labs done one month later showed improving AST and ALT levels of 92 and 149, respectively. Bilirubin levels improved to a level of 3.8. Discussion: This case highlights a rare association between acute liver dysfunction and norovirus gastroenteritis. To our knowledge, this is the first case report demonstrating a rise of this magnitude with regard to AST and ALT levels in a patient with norovirus infection. Although this association is rare, clinicians should consider acute liver injury as a possible extra-intestinal manifestation of norovirus infection.

Norovirus (NoV) infection is one of the most common non-bacterial causes of gastroenteritis among the population worldwide. From the point of view of medical diagnostics, it is important to develop a system that would sensitively and selectively detect norovirus from a patient's sample in order to control and limit its spread. In this paper, we present a stable and sensitive NoV (mouse model) detection matrix in infected food samples. The bio-platform was made of a modified gold electrode with a self-assembled l-cysteine monolayer, covered with gold nanoparticles, a linker and an antibody specific to the VP1 surface protein of the virus. Binding of the VP1 protein to the antibody caused a decrease in the current strength confirmed by electrochemical techniques - cyclic voltammetry (CV) and differential pulse voltammetry. The reduction of the current was proportional to the concentration of NoV sample. The biosensors showed high sensitivity and linearity in a range from 1 × 10-9 to 1 × 10-18 TCID50, with the detection limit of 1 × 10-18 TCID50. CV showed a diffusion-controlled process. In addition, each modification step was confirmed by scanning electron microscopy, electrochemical impedance spectroscopy, and CV. The described immunosensor showed excellent recovery values, good linearity and long-term stability, crucial parameters for biosensor construction.

A prospective population-based cohort study with a nested case-control study was conducted to estimate the incidence of gastroenteritis and the associated pathogens in the general Dutch population. Follow-up of two consecutive cohorts was performed by weekly reporting cards from December 1998 to December 1999. Cases and controls in the case-control study supplied a questionnaire and stool samples. The standardized gastroenteritis incidence was 283 per 1,000 person-years. The incidence rose with increasing level of education and was higher for persons with a history of diarrhea and for young children. Bacterial pathogens accounted for 5% of cases, bacterial toxins for 9%, parasites for 6%, and viral pathogens for 21%, with Norwalk-like virus (NLV) as the leading pathogen in 11% of cases. The gastroenteritis incidence was higher than that reported for England, but lower than for the United States. In community cases, viral pathogens are the leading cause of gastroenteritis, with NLV being the number one cause of illness in all age groups but one. In many countries, preventive measures are implemented to decrease bacterial infections. However, additional prevention of viral infections, especially NLV, might significantly decrease the number of gastroenteritis cases in the community.

Norovirus is the common cause of gastroenteritis in humans. There is no report of liver dysfunction in children caused by norovirus infection. Baclofen has been used mainly to treat spasticity in children with cerebral palsy. Hepatotoxicity of baclofen has not been previously described in children. This report describes the case of acute liver dysfunction in the course of norovirus gastroenteritis in a child with cerebral palsy (CP) on baclofen. A 7-year 7month-old child who diagnosed spastic quadriplegic cerebral palsy showed mild fever and diarrhea. He started taking baclofen a week before the symptom started. His illness was diagnosed as norovirus gastroenteritis, but liver dysfunction accompanied this gastroenteritis (AST/ALT 589/401 (IU/L)). He recovered completely within 2 weeks without any damage left. When a child with cerebral palsy gets norovirus enteritis while taking baclofen, it would be necessary to close monitoring for liver failure.

Rotavirus and other viruses causing acute childhood gastroenteritis

Relationship between GII.3 norovirus infections and blood group antigens in young children in Tunisia