The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Dirk Jochmans - One of the best experts on this subject based on the ideXlab platform.
-
The Enterovirus Protease Inhibitor Rupintrivir Exerts Cross-Genotypic Anti-Norovirus Activity and Clears Cells From the Norovirus Replicon
Antimicrobial agents and chemotherapy, 2014Co-Authors: Joana Rocha-pereira, Maria São José Nascimento, Rolf Hilgenfeld, Johan Neyts, Dirk JochmansAbstract:Potent and safe inhibitors of Norovirus replication are needed for the treatment and prophylaxis of Norovirus infections. We here report that the in vitro anti-Norovirus activity of the protease inhibitor rupintrivir is extended to murine Noroviruses and that rupintrivir clears human cells from their Norwalk replicon after only two passages of antiviral pressure. In addition, we demonstrate that rupintrivir inhibits the human Norovirus (genogroup II [GII]) protease and further explain the inhibitory effect of the molecule by means of molecular modeling on the basis of the crystal structure of the Norwalk virus protease. The combination of rupintrivir with the RNA-dependent RNA polymerase inhibitors 2′-C-methylcytidine and favipiravir (T-705) resulted in a merely additive antiviral effect. The fact that rupintrivir is active against Noroviruses belonging to genogroup I (Norwalk virus), genogroup V (murine Norovirus), and the recombinant 3C-like protease of a GII Norovirus suggests that the drug exerts cross-genotypic anti-Norovirus activity and will thus most likely be effective against the clinically relevant human Norovirus strains. The design of antiviral molecules targeting the Norovirus protease could be a valuable approach for the treatment and/or prophylaxis of Norovirus infections.
Ben Lopman - One of the best experts on this subject based on the ideXlab platform.
-
Norovirus infection and disease in an ecuadorian birth cohort association of certain Norovirus genotypes with host fut2 secretor status
The Journal of Infectious Diseases, 2015Co-Authors: Ben Lopman, Tarak Trivedi, Yosselin Vicuna, Veronica Costantini, Nikail R Collins, Nicole Gregoricus, Carlos Sandoval, Umesh D Parashar, Nely BroncanoAbstract:Background. Although Norovirus is the most common cause of gastroenteritis, there are few data on the community incidence of infection/disease or the patterns of acquired immunity or innate resistance to Norovirus. Methods. We followed a community-based birth cohort of 194 children in Ecuador with the aim to estimate (1) the incidence of Norovirus gastroenteritis from birth to age 3 years, (2) the protective effect of Norovirus infection against subsequent infection/disease, and (3) the association of infection and disease with FUT2 secretor status. Results. Over the 3-year period, we detected a mean of 2.26 diarrheal episodes per child (range, 0–12 episodes). Norovirus was detected in 260 samples (18%) but was not found more frequently in diarrheal samples (79 of 438 [18%]), compared with diarrhea-free samples (181 of 1016 [18%]; P= .919). A total of 66% of children had at least 1 Norovirus infection during the first 3 years of life, and 40% of children had 2 infections. Previous Norovirus infections were not associated with the risk of subsequent infection. All genogroup II, genotype 4 (GII.4) infections were among secretor-positive children (P< .001), but higher rates of non-GII.4 infections were found in secretor-negative children (relative risk, 0.56; P= .029). Conclusions. GII.4 infections were uniquely detected in secretor-positive children, while non-GII.4 infections were more often found in secretor-negative children.
-
Norovirus Disease in the United States
Emerging infectious diseases, 2013Co-Authors: Aron J. Hall, Daniel C Payne, Jan Vinjé, Ben Lopman, Manish M. Patel, Paul A. Gastañaduy, Umesh D ParasharAbstract:Recognition of the public health impact of Noroviruses has increased in recent years, driven largely by an abundance of reported outbreaks. A systematic literature review identified >900 published reports of laboratory-confirmed Norovirus outbreaks during 1993–2011 (1). In contrast, studies assessing endemic Norovirus disease are limited primarily to etiologic studies of acute gastroenteritis among children seeking medical care (2). Such prevalence studies provide valuable insights into the role of Norovirus among patients with acute gastroenteritis. However, robust assessment of the Norovirus disease burden, which herein refers to the annual number of illnesses and associated outcomes, requires population-based incidence estimates, ideally from national or nationally representative surveillance. However, there are several challenges to generating such estimates for Norovirus in the United States, including lack of a widely used, rapid, and sensitive clinical assay; no public health reporting requirement for individual cases; low health care–seeking rates of patients with acute gastroenteritis; and poor sensitivity of Norovirus-specific codes in national administrative databases (3). Before 2008, only 1 published report estimated the burden of Norovirus disease in the United States (4). In that report, as part of a broader effort to estimate the US burden of foodborne disease, Mead et al. generated pathogen-specific estimates of illnesses, hospitalizations, and deaths, and they estimated the fraction of these outcomes caused by foodborne disease transmission. Annual Norovirus-associated illnesses (23 million), hospitalizations (50,000), and deaths (310) were based on extrapolation of the Norovirus-attributable proportion from a single community-based study in the Netherlands and applied to the US all-cause acute gastroenteritis incidence from the National Hospital Discharge Survey (NHDS) and the first Population Survey of the Foodborne Diseases Active Surveillance Network (FoodNet). Although limited by the absence of direct US data on Norovirus prevalence or incidence, this landmark study demonstrated the predominant role of Norovirus in causing foodborne disease and became the most widely cited estimate of the US Norovirus disease burden for more than a decade. We review a collection of subsequently published studies that provided population-based incidence rates of Norovirus disease in the United States. By comparing the various methods and triangulating the results, we provide summary estimates of the overall US Norovirus disease burden, including specific estimates by age groups and disease outcomes. This review facilitates identification of key groups that would benefit from prevention strategies aimed at controlling Norovirus and provides the grist for development of appropriate interventions, including vaccines. Such data are particularly timely and relevant given that a candidate Norovirus vaccine is approaching a phase 3 efficacy trial and could potentially be licensed within the next 5–7 years (5).
-
risk factors for symptomatic and asymptomatic Norovirus infection in the community
Epidemiology and Infection, 2011Co-Authors: Gemma Phillips, Lc C. Rodrigues, Ben LopmanAbstract:The objective of this study was to investigate risk factors for Norovirus-associated infectious intestinal disease (IID) and asymptomatic Norovirus infection. Individuals with IID and healthy controls were recruited in a community-based study in England (1993–1996). This is the first risk-factor study to use viral load measurements, generated by real-time RT–PCR, to identify cases of Norovirus-associated IID and asymptomatic infections. Using multivariable logistic regression the main risk factor identified for Norovirus-associated IID was contact with a person with IID symptoms. Infectious contacts accounted for 54% of Norovirus cases in young children and 39% of Norovirus cases in older children and adults. For young children, contacts outside the household presented the highest risk ; for older children and adults, the highest risk was associated with child contacts inside the household. Foreign travel and consumption of shellfish increased the risk of Norovirus-associated IID. Lifestyle and dietary factors were associated with a decreased risk of both Norovirus-associated IID and asymptomatic infection. No risk factors were identified for asymptomatic Norovirus infection.
-
Impact of an Emergent Norovirus Variant in 2009 on Norovirus Outbreak Activity in the United States
Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 2011Co-Authors: Catherine Yen, Umesh D Parashar, Jan Vinjé, Ben Lopman, Mary E. Wikswo, Aron J. HallAbstract:In October 2009, a new genogroup II, type 4 (GII.4) Norovirus variant was identified in the United States. We collected Norovirus outbreak data from 30 states to assess whether this new strain was associated with increased acute gastroenteritis activity. No increase in Norovirus outbreaks was observed during the 2009-2010 winter.
-
community incidence of Norovirus associated infectious intestinal disease in england improved estimates using viral load for Norovirus diagnosis
American Journal of Epidemiology, 2010Co-Authors: Gemma Phillips, Clarence C Tam, Stefano Conti, Laura C Rodrigues, David W Brown, Miren Iturrizagomara, Jim Gray, Ben LopmanAbstract:Existing estimates of the incidence of infectious intestinal disease (IID) caused by Norovirus are based on electron microscopy or reverse transcription-polymerase chain reaction (RT-PCR). Neither method accurately represents Norovirus disease burden: Electron microscopy has poor diagnostic sensitivity, and RT-PCR has poor diagnostic specificity. In this study, viral load measurements were used to identify cases of Norovirus-associated IID and to produce new incidence estimates for England. IID cases were ascertained in the Study of Infectious Intestinal Disease in England (1993-1996), and stool specimens were tested by semiquantitative real-time RT-PCR for Norovirus. The age-adjusted community incidence of Norovirus-associated IID was 4.5/100 person-years (95% credibility interval: 3.8, 5.2), equating to 2 million episodes/year. Among children aged less than 5 years, the community incidence was 21.4/100 person-years (95% credibility interval: 15.9, 27.7), and the incidence of consultations to general practitioners for Norovirus-associated IID was 3.2/100 person-years (95% credibility interval: 2.6, 3.8), with 100,000 children visiting their general practitioner for Norovirus-associated IID each year. Norovirus is the most common cause of IID in the community in England and is responsible for a similar number of pediatric primary care consultations as rotavirus.
Umesh D Parashar - One of the best experts on this subject based on the ideXlab platform.
-
Norovirus infection in older adults epidemiology risk factors and opportunities for prevention and control
Infectious Disease Clinics of North America, 2017Co-Authors: Cristina V Cardemil, Umesh D Parashar, Aron J. HallAbstract:Norovirus is the leading cause of acute gastroenteritis. In older adults, it is responsible for an estimated 3.7 million illnesses; 320,000 outpatient visits; 69,000 emergency department visits; 39,000 hospitalizations; and 960 deaths annually in the United States. Older adults are particularly at risk for severe outcomes, including prolonged symptoms and death. Long-term care facilities and hospitals are the most common settings for Norovirus outbreaks in developed countries. Diagnostic platforms are expanding. Several Norovirus vaccines in clinical trials have the potential to reap benefits. This review summarizes current knowledge on Norovirus infection in older adults.
-
population based incidence rates of diarrheal disease associated with Norovirus sapovirus and astrovirus in kenya
PLOS ONE, 2016Co-Authors: Nicole Gregoricus, Umesh D Parashar, Jan Vinjé, Kayoko Shioda, Leonard Cosmas, Allan Audi, Joel M Montgomery, Daniel R Feikin, Robert F BreimanAbstract:Background Diarrheal diseases remain a major cause of mortality in Africa and worldwide. While the burden of rotavirus is well described, population-based rates of disease caused by Norovirus, sapovirus, and astrovirus are lacking, particularly in developing countries. Methods Data on diarrhea cases were collected through a population-based surveillance platform including healthcare encounters and household visits in Kenya. We analyzed data from June 2007 to October 2008 in Lwak, a rural site in western Kenya, and from October 2006 to February 2009 in Kibera, an urban slum. Stool specimens from diarrhea cases of all ages who visited study clinics were tested for Norovirus, sapovirus, and astrovirus by RT-PCR. Results Of 334 stool specimens from Lwak and 524 from Kibera, 85 (25%) and 159 (30%) were positive for Norovirus, 13 (4%) and 31 (6%) for sapovirus, and 28 (8%) and 18 (3%) for astrovirus, respectively. Among Norovirus-positive specimens, genogroup II predominated in both sites, detected in 74 (87%) in Lwak and 140 (88%) in Kibera. The adjusted community incidence per 100,000 person-years was the highest for Norovirus (Lwak: 9,635; Kibera: 4,116), followed by astrovirus (Lwak: 3,051; Kibera: 440) and sapovirus (Lwak: 1,445; Kibera: 879). For all viruses, the adjusted incidence was higher among children aged <5 years (Norovirus: 22,225 in Lwak and 17,511 in Kibera; sapovirus: 5,556 in Lwak and 4,378 in Kibera; astrovirus: 11,113 in Lwak and 2,814 in Kibera) compared to cases aged ≥5 years. Conclusion Although limited by a lack of controls, this is the first study to estimate the outpatient and community incidence rates of Norovirus, sapovirus, and astrovirus across the age spectrum in Kenya, suggesting a substantial disease burden imposed by these viruses. By applying adjusted rates, we estimate approximately 2.8–3.3 million, 0.45–0.54 million, and 0.77–0.95 million people become ill with Norovirus, sapovirus, and astrovirus, respectively, every year in Kenya.
-
the vast and varied global burden of Norovirus prospects for prevention and control
PLOS Medicine, 2016Co-Authors: Benjamin A Lopman, Carl D Kirkwood, Duncan A Steele, Umesh D ParasharAbstract:Globally, Norovirus is associated with approximately one-fifth of all diarrhea cases, with similar prevalence in both children and adults, and is estimated to cause over 200,000 deaths annually in developing countries. Norovirus is an important pathogen in a number of high-priority domains: it is the most common cause of diarrheal episodes globally, the principal cause of foodborne disease outbreaks in the United States, a key health care–acquired infection, a common cause of travel-associated diarrhea, and a bane for deployed military troops. Partly as a result of this ubiquity and burden across a range of different populations, identifying target groups and strategies for intervention has been challenging. And, on top of the breadth of this public health problem, there remain important gaps in scientific knowledge regarding Norovirus, especially with respect to disease in low-income settings. Many pathogens can cause acute gastroenteritis. Historically, rotavirus was the most common cause of severe disease in young children globally. Now, vaccines are available for rotavirus and are universally recommended by the World Health Organization. In countries with effective rotavirus vaccination programs, disease due to that pathogen has decreased markedly, but Norovirus persists and is now the most common cause of pediatric gastroenteritis requiring medical attention. However, the data supporting the precise role of Norovirus in low- and middle-income settings are sparse. With vaccines in the pipeline, addressing these and other important knowledge gaps is increasingly pressing. We assembled an expert group to assess the evidence for the global burden of Norovirus and to consider the prospects for Norovirus vaccine development. The group assessed the evidence in the areas of burden of disease, epidemiology, diagnostics, disease attribution, acquired immunity, and innate susceptibility, and the group considered how to bring Norovirus vaccines from their current state of development to a viable product that will benefit global health.
-
Norovirus infection and disease in an ecuadorian birth cohort association of certain Norovirus genotypes with host fut2 secretor status
The Journal of Infectious Diseases, 2015Co-Authors: Ben Lopman, Tarak Trivedi, Yosselin Vicuna, Veronica Costantini, Nikail R Collins, Nicole Gregoricus, Carlos Sandoval, Umesh D Parashar, Nely BroncanoAbstract:Background. Although Norovirus is the most common cause of gastroenteritis, there are few data on the community incidence of infection/disease or the patterns of acquired immunity or innate resistance to Norovirus. Methods. We followed a community-based birth cohort of 194 children in Ecuador with the aim to estimate (1) the incidence of Norovirus gastroenteritis from birth to age 3 years, (2) the protective effect of Norovirus infection against subsequent infection/disease, and (3) the association of infection and disease with FUT2 secretor status. Results. Over the 3-year period, we detected a mean of 2.26 diarrheal episodes per child (range, 0–12 episodes). Norovirus was detected in 260 samples (18%) but was not found more frequently in diarrheal samples (79 of 438 [18%]), compared with diarrhea-free samples (181 of 1016 [18%]; P= .919). A total of 66% of children had at least 1 Norovirus infection during the first 3 years of life, and 40% of children had 2 infections. Previous Norovirus infections were not associated with the risk of subsequent infection. All genogroup II, genotype 4 (GII.4) infections were among secretor-positive children (P< .001), but higher rates of non-GII.4 infections were found in secretor-negative children (relative risk, 0.56; P= .029). Conclusions. GII.4 infections were uniquely detected in secretor-positive children, while non-GII.4 infections were more often found in secretor-negative children.
-
incidence of medically attended Norovirus associated acute gastroenteritis in four veteran s affairs medical center populations in the united states 2011 2012
PLOS ONE, 2015Co-Authors: Scott Grytdal, David Rimland, Hannah S Shirley, Maria C Rodriguezbarradas, Matthew Bidwell Goetz, Sheldon T Brown, Cynthia Luceroobusan, Mark Holodniy, Christopher J Graber, Umesh D ParasharAbstract:An estimated 179 million acute gastroenteritis (AGE) illnesses occur annually in the United States. The role of Noroviruses in hospital-related AGE has not been well-documented in the U. S. We estimated the population incidence of community- acquired outpatient and inpatient Norovirus AGE encounters, as well as hospital-acquired inpatient Norovirus AGE among inpatients at four Veterans Affairs (VA) Medical Centers (VAMCs). Fifty (4%) of 1,160 stool specimens collected ≤7 days from symptom onset tested positive for Norovirus. During a one year period, the estimated incidence of outpatient, community- and hospital-acquired inpatient Norovirus AGE was 188 cases, 11 cases, and 54 cases/ 100,000 patients, respectively. This study demonstrates the incidence of outpatient and community- and hospital-acquired inpatient Norovirus AGE among the VA population seeking care at these four VAMCs.
Joana Rocha-pereira - One of the best experts on this subject based on the ideXlab platform.
-
The Enterovirus Protease Inhibitor Rupintrivir Exerts Cross-Genotypic Anti-Norovirus Activity and Clears Cells from the Norovirus Replicon
2016Co-Authors: Joana Rocha-pereira, B M. S. J. Nascimento, A Q., D R. Hilgenfeld, D J. Neyts, B D. JochmansbAbstract:Potent and safe inhibitors of Norovirus replication are needed for the treatment and prophylaxis of Norovirus infections. We here report that the in vitro anti-Norovirus activity of the protease inhibitor rupintrivir is extended to murine Noroviruses and that rupintrivir clears human cells from their Norwalk replicon after only two passages of antiviral pressure. In addition, we demonstrate that rupintrivir inhibits the human Norovirus (genogroup II [GII]) protease and further explain the inhibitory ef-fect of the molecule by means of molecular modeling on the basis of the crystal structure of the Norwalk virus protease. The combination of rupintrivir with the RNA-dependent RNA polymerase inhibitors 2=-C-methylcytidine and favipiravir (T-705) resulted in a merely additive antiviral effect. The fact that rupintrivir is active against Noroviruses belonging to genogroup I (Norwalk virus), genogroup V (murine Norovirus), and the recombinant 3C-like protease of a GII Norovirus suggests that the drug exerts cross-genotypic anti-Norovirus activity and will thus most likely be effective against the clinically relevant human Norovirus strains. The design of antiviral molecules targeting the Norovirus protease could be a valuable approach for the treat-ment and/or prophylaxis of Norovirus infections. Human Noroviruses are a major cause of food-borne illness,accountable for 50 % of all-etiologies outbreaks of acute gas-troenteritis (both in developing and developed countries) (1, 2). Outbreaks often occur in long-term-care facilities and hospitals where the elderly and immunocompromised can become severel
-
The Enterovirus Protease Inhibitor Rupintrivir Exerts Cross-Genotypic Anti-Norovirus Activity and Clears Cells From the Norovirus Replicon
Antimicrobial agents and chemotherapy, 2014Co-Authors: Joana Rocha-pereira, Maria São José Nascimento, Rolf Hilgenfeld, Johan Neyts, Dirk JochmansAbstract:Potent and safe inhibitors of Norovirus replication are needed for the treatment and prophylaxis of Norovirus infections. We here report that the in vitro anti-Norovirus activity of the protease inhibitor rupintrivir is extended to murine Noroviruses and that rupintrivir clears human cells from their Norwalk replicon after only two passages of antiviral pressure. In addition, we demonstrate that rupintrivir inhibits the human Norovirus (genogroup II [GII]) protease and further explain the inhibitory effect of the molecule by means of molecular modeling on the basis of the crystal structure of the Norwalk virus protease. The combination of rupintrivir with the RNA-dependent RNA polymerase inhibitors 2′-C-methylcytidine and favipiravir (T-705) resulted in a merely additive antiviral effect. The fact that rupintrivir is active against Noroviruses belonging to genogroup I (Norwalk virus), genogroup V (murine Norovirus), and the recombinant 3C-like protease of a GII Norovirus suggests that the drug exerts cross-genotypic anti-Norovirus activity and will thus most likely be effective against the clinically relevant human Norovirus strains. The design of antiviral molecules targeting the Norovirus protease could be a valuable approach for the treatment and/or prophylaxis of Norovirus infections.
Johan Nordgren - One of the best experts on this subject based on the ideXlab platform.
-
Norovirus infection and hbga host genetic susceptibility in a birth community cohort rio de janeiro brazil
Infection Genetics and Evolution, 2020Co-Authors: Carina Pacheco Cantelli, Fabio Correia Malta, Denise Cotrim Da Cunha, Patricia Brasil, Marize Pereira Miagostovich, Marcia Terezinha Baroni De Moraes, Tulio Machado Fumian, Johan Nordgren, Lennart Svensson, Jose Paulo Gagliardi LeiteAbstract:Norovirus has emerged as an important viral agent of acute pediatric gastroenteritis, with a growing genetic diversity reported in the last decades. Histo-blood group antigens (HBGAs) present on the surface of enterocytes are susceptibility factors for Norovirus infection and differ between populations which could affects the epidemiology and evolution of these viruses. This study investigated the frequency, incidence and genetic diversity of Noroviruses in a cohort of rotavirus A vaccinated children in association to the host HBGA (Secretor/Lewis) genetic susceptibility profile. Norovirus genogroups I and II (GI/GII) were screened by RT-qPCR in 569 stool samples from 132 children followed-up from birth to 11 months of age during 2014--2018. Noroviruses were identified in 21.2% of children enrolled in this study, with a Norovirus detection rate of 5.6% (32/569), in 17.1% and 4.7% of acute diarrheic episodes (ADE) and non-ADE, respectively. The Norovirus incidence was 5.8 infections per 100 child-months. Partial nucleotide sequencing characterized six different Norovirus genotypes, with GII.4 Sydney 2012 being detected in 50% associated with three different polymerase genotypes (GII·P31, GII·P16 and GII·P4 New Orleans 2009). FUT3 genotyping was yielded seven new mutations in this population. A significant association between symptomatic Norovirus infection and secretor profile could be inferred.
-
Secretor Status is Associated with Susceptibility to Disease in a Large GII.6 Norovirus Foodborne Outbreak
Food and Environmental Virology, 2019Co-Authors: Sumit Sharma, Beatrice Carlsson, Marie Hagbom, Joanna Nederby Öhd, Mona Insulander, Ronnie Eriksson, Magnus Simonsson, Micael Widerström, Johan NordgrenAbstract:Norovirus is commonly associated with food and waterborne outbreaks. Genetic susceptibility to Norovirus is largely dependent on presence of histo-blood group antigens (HBGA), specifically ABO, secretor, and Lewis phenotypes. The aim of the study was to determine the association between HBGAs to Norovirus susceptibility during a large Norovirus foodborne outbreak linked to genotype GII.6 in an office-based company in Stockholm, Sweden, 2015. A two-episode outbreak with symptoms of diarrhea and vomiting occurred in 2015. An online questionnaire was sent to all 1109 employees that had worked during the first outbreak episode. Food and water samples were collected from in-house restaurant and tested for bacterial and viral pathogens. In addition, fecal samples were collected from 8 employees that had diarrhea. To investigate genetic susceptibility during the outbreak, 98 saliva samples were analyzed for ABO, secretor, and Lewis phenotypes using ELISA. A total of 542 of 1109 (49%) employees reported gastrointestinal symptoms. All 8 fecal samples tested positive for GII Norovirus, which was also detected in coleslaw collected from the in-house restaurant. Eating at the in-house restaurant was significantly associated with risk of symptom development. Nucleotide sequencing was successful for 5/8 fecal samples and all belonged to the GII.6 genotype. HBGA characterization showed a strong secretor association to Norovirus-related symptoms ( P = 0.014). No association between Norovirus disease and ABO phenotypes was observed. The result of this study shows that non-secretors were significantly less likely to report symptoms in a large foodborne outbreak linked to the emerging GII.6 Norovirus strain.
-
emergence of a novel gii 17 Norovirus end of the gii 4 era
Eurosurveillance, 2015Co-Authors: M De Graaf, Harry Vennema, Joanne Hewitt, Johan Nordgren, Filemon Bucardo, J Van Beek, Alexander T Podkolzin, K Templeton, Janet Mans, Gabor ReuterAbstract:In the winter of 2014/15 a novel GII.P17-GII.17 Norovirus strain (GII.17 Kawasaki 2014) emerged, as a major cause of gastroenteritis outbreaks in China and Japan. Since their emergence these novel GII.P17-GII.17 viruses have replaced the previously dominant GII.4 genotype Sydney 2012 variant in some areas in Asia but were only detected in a limited number of cases on other continents. This perspective provides an overview of the available information on GII.17 viruses in order to gain insight in the viral and host characteristics of this Norovirus genotype. We further discuss the emergence of this novel GII.P17-GII.17 Norovirus in context of current knowledge on the epidemiology of Noroviruses. It remains to be seen if the currently dominant Norovirus strain GII.4 Sydney 2012 will be replaced in other parts of the world. Nevertheless, the public health community and surveillance systems need to be prepared in case of a potential increase of Norovirus activity in the next seasons caused by this novel GII.P17-GII.17 Norovirus.
-
Asymptomatic Norovirus infections in Nicaraguan children and its association with viral properties and histo-blood group antigens.
Pediatric Infectious Disease Journal, 2010Co-Authors: Filemon Bucardo, Johan Nordgren, Beatrice Carlsson, Elin Kindberg, Margarita Paniagua, Roland Möllby, Lennart SvenssonAbstract:Background: It has been previously reported that histo-blood group antigens (HBGAs) and particularly secretor status provides protection against symptomatic Norovirus infection, but it remains unclear to what extent this includes asymptomatic infections in children. Methods: To explore whether HBGAs or certain viral genotypes are associated with asymptomatic Norovirus infections in a pediatric population in Nicaragua, we investigated 163 children andlt;= 5 years of age, without a recent history of diarrhea (andlt;= 10 days). Results: Asymptomatic Norovirus infections were observed in 11.7% (19/163), with children andlt;= 6 months of age being most frequently infected (16%). Of the 19 Norovirus-positive children, 4 (21%) and 10 (53%) were infected with genogroups GI and GII, respectively, and 4 children (21%) were infected with viruses of both genogroups. Most children had andgt;= 10(6) viral genomes per gram of feces. Nucleotide sequence analysis (15/19) revealed uncommon genotypes, such as, GII. 7 (n = 5) and GII. 2 (n = 3). An interesting observation was the low frequency of Norovirus GII. 4 strains among the asymptomatic children. AB blood type, Lewis a (Lea(a+b-)) phenotype and nonsecretor genotype (se(428)se(428)) were not found among the asymptomatic children, but they occurred in population controls. Conclusions: Frequency of asymptomatic Norovirus infections was similar to that observed in symptomatic children from Nicaragua. Norovirus GII. 2 and GII. 7 were frequently detected but the globally dominating GII. 4 was infrequent. Host genetic factors previously observed to be associated with protection against symptomatic Norovirus infection were not found in this study.
