Norovirus gastroenteritis causes severe and lethal complications after chemotherapy and hematopoietic stem cell transplantation.

Norovirus (NV) infections are a frequent cause of gastroenteritis (GE), but data on this disease in immunocompromised patients are limited. We analyzed an NV outbreak, which affected immunosuppressed patients in the context of chemotherapy or HSCT. On recognition, 7 days after admission of the index patient, preventive measures were implemented. Attack rates were only 3% (11/334) and 10% (11/105) among patients and staff members, respectively. The median duration of symptoms was 7 days in patients compared with only 3 days in staff members (P = .02). Three patients died of the NV infection. Commonly used clinical diagnostic criteria (Kaplan-criteria) were unsuitable because they applied to 11 patients with proven NV-GE but also to 15 patients without NV-GE. With respect to the therapeutic management, it is important to differentiate intestinal GVHD from NV-GE. Therefore, we analyzed the histopathologic patterns in duodenal biopsies, which were distinctive in both conditions. Stool specimens in patients remained positive for NV-RNA for a median of 30 days, but no transmission was observed beyond an asymptomatic interval of 48 hours. NV-GE is a major threat to patients with chemotherapy or HSCT, and meticulous measures are warranted to prevent transmission of NV to these patients.

Norovirus non-structural protein p20 leads to impaired restitution of epithelial defects by inhibition of actin cytoskeleton remodelling.

OBJECTIVE: Norovirus is the most common cause of acute gastroenteritis in humans worldwide. Typical symptoms are vomiting, nausea and severe watery diarrhea. Because of the lack of cell lines susceptible to human norovirus infection, pathomechanisms and replication cycle are largely unknown. Here, we address the issue of how norovirus infection could lead to epithelial barrier dysfunction. MATERIAL AND METHODS: Expression of the non-structural norovirus protein p20 in the epithelial cell line HT-29/B6 was activated through a tetracycline sensitive promoter. Tight junction proteins were studied by Western blot and confocal laser scanning microscopy. Apoptoses were detected in TUNEL stainings. Epithelial restitution was monitored by conductance scanning after induction of single cell lesions. RESULTS: Changes in the expression or localization of the tight junction proteins occludin and/or claudin-1, -2,- 3, -4, -5, -7 and -8 could be ruled out to mediate epithelial barrier modulation. Cell motility was also unaltered by p20. Investigation of epithelial apoptosis revealed an accumulation of apoptic cells in epithelial monolayers after induction of p20 expression. In epithelial cell restitution assays, an arrest was identified in p20 expressing cells. Fluorescence microscopy revealed an inability for condensation and redistribution of cellular actin, which led to a reduced transepithelial electrical resistance. CONCLUSIONS: Functional data for norovirus protein p20 suggest a role in modulation of the actin cytoskeleton leading to barrier dysfunction through impairment of restitution of epithelial defects.

Chronic norovirus infection after kidney transplantation: molecular evidence for immune-driven viral evolution.

BACKGROUND: Norovirus infection is the most common cause of acute self-limiting gastroenteritis. Only 3 cases of chronic norovirus infection in adult solid organ transplant recipients have been reported thus far. METHODS: This case series describes 9 consecutive kidney allograft recipients with chronic norovirus infection with persistent virus shedding and intermittent diarrhea for a duration of 97-898 days. The follow-up includes clinical course, type of immunosuppression, and polymerase chain reaction for norovirus. Detailed molecular analyses of virus isolates from stool specimens over time were performed. RESULTS: The intensity of immunosuppression correlated with the diarrheal symptoms but not with viral shedding. Molecular analysis of virus strains from each patient revealed infection with different variants of GII.4 strains in 7 of 9 patients. Another 2 patients were infected with either the GII.7 or GII.17 strain. No molecular evidence for nosocomial transmission in our outpatient clinic was found. Capsid sequence alignments from follow-up specimens of 4 patients showed accumulation of mutations over time, resulting in amino acid changes predominantly in the P2 and P1-2 region. Up to 25 amino acids mutations were accumulated over a 683-day period in the patient with an 898-day shedding history. CONCLUSION: Norovirus infection may persist in adult renal allograft recipients with or without clinical symptoms. No evidence for nosocomial transmission in adult renal allograft recipients was found in our study. Molecular analysis suggests continuous viral evolution in immunocompromised patients who are unable to clear this infection.

Epidemiology of hepatitis A virus infections, Germany, 2007-2008.

Approximately 60% of hepatitis A virus infections in Germany occur in persons without a travel history to disease-endemic areas and for whom sources of infection are unknown. Recommendation of pretravel vaccination fails to prevent the remaining imported infections. Using enhanced surveillance in 2007-2008, we analyzed epidemiologic patterns of hepatitis A in Germany and appropriateness and adequacy of current immunization recommendations. Young patients with a migration background who had visited friends and family in their ancestral countries accounted for most imported cases. Phylogenetic analysis showed high diversity of sequence data and clustering of strains with similar regions of origin or patient migration backgrounds. Virologic findings are compatible with those of low-incidence countries, where virtually all infections are directly or indirectly imported from other regions. Germans with a migration background are seen as a special risk group so far insufficiently reached by pretravel vaccination advice.

Norovirus illness is a global problem: emergence and spread of norovirus GII.4 variants, 2001-2007.

BACKGROUND: Noroviruses (NoVs) are the most common cause of viral gastroenteritis. Their high incidence and importance in health care facilities result in a great impact on public health. Studies from around the world describing increasing prevalence have been difficult to compare because of differing nomenclatures for variants of the dominant genotype, GII.4. We studied the global patterns of GII.4 epidemiology in relation to its genetic diversity. METHODS: Data from NoV outbreaks with dates of onset from January 2001 through March 2007 were collected from 15 institutions on 5 continents. Partial genome sequences (n=775) were collected, allowing phylogenetic comparison of data from different countries. RESULTS: The 15 institutions reported 3098 GII.4 outbreaks, 62% of all reported NoV outbreaks. Eight GII.4 variants were identified. Four had a global distribution--the 1996, 2002, 2004, and 2006b variants. The 2003Asia and 2006a variants caused epidemics, but they were geographically limited. Finally, the 2001 Japan and 2001 Henry variants were found across the world but at low frequencies. CONCLUSIONS: NoV epidemics resulted from the global spread of GII.4 strains that evolved under the influence of population immunity. Lineages show notable (and currently unexplained) differences in geographic prevalence. Establishing a global NoV network by which data on strains with the potential to cause pandemics can be rapidly exchanged may lead to improved prevention and intervention strategies.

Seroprevalence and molecular epidemiology of enterovirus 71 in Germany.

Enterovirus 71 (EV71) has emerged as a significant pathogen with potential to cause large outbreaks. Because little is known about its seroprevalence and molecular epidemiology in Germany, data for 1997-2007 are presented. Four hundred thirty-six sera from persons aging 10 months to 75 years were tested in a neutralisation test; 63.4% of pre-school children were seronegative, whereas about 75% of adults had antibodies to EV71. Phylogenetic analysis of 28 isolates associated with neurological or cutaneous manifestations showed that isolates belonging to genogroup C1 predominated in 2000-2005, followed by a change to genogroup C2 in 2006 and 2007. This shows the importance of monitoring the diversity of one of the most relevant neurotropic enteroviruses.

Low-density lipoprotein receptor variants are associated with spontaneous and treatment-induced recovery from hepatitis C virus infection.

Low-density lipoprotein receptor (LDLR) is involved in the entry of hepatitis C virus (HCV) in host cells. We investigated whether three single-nucleotide alterations within LDLR might be associated with the course of hepatitis C infection and response to antiviral therapy. We enrolled 651 individuals with chronic HCV infection who had received interferon-based combination therapy, 174 individuals with self-limited HCV infection, and 516 healthy controls. LDLR c.1171G>A, c.1413G>A, and c.*52G>A genotyping was performed by real-time PCR-based assays. HCV genotype 1-infected individuals who were homozygous for 3'UTR c.*52G were at increased risk for virologic non-response to antiviral therapy compared to virologic responders (66.3% vs. 51.0%, p=0.001). Furthermore, compared to healthy controls, self-limited HCV genotype 1 infection was significantly associated with c.1171A (15.1% vs. 6.6%, p=0.006) and negatively associated with c.1413G>A heterozygosity (33.0% vs. 46.1%, p=0.023). The data indicate that LDLR alterations are correlated with response to interferon-based combination therapy and with self-limitation of HCV 1 infection.

Aetiology of community-acquired, acute gastroenteritis in hospitalised adults: a prospective cohort study.

BACKGROUND: The aetiology of severe gastroenteritis leading to hospitalisation in adults frequently remains unclear. Our objective was to study the causes and characteristics of community-acquired, acute gastroenteritis in adult hospitalized patients to support the clinical management of these patients. METHODS: From August 2005 to August 2007, we conducted a prospective cohort study among patients > or =18 y hospitalized with community-acquired gastroenteritis in a university hospital in Berlin, Germany. Stool specimens were examined for 26 gastrointestinal pathogens, supplemented by serologic tests for antibodies to Campylobacter spp., Yersinia spp., and Entamoeba histolytica. Patient data on demographics and clinical presentation were recorded and analyzed. Coexisting medical conditions were assessed using the Charlson Comorbidity Index score. RESULTS: Of 132 patients presenting with acute community-acquired gastroenteritis, 104 were included in the study. A non-infectious aetiology was diagnosed in 8 patients (8%). In 79 (82%) of the remaining 96 patients at least one microorganism was identified. Campylobacter spp. (35%) was detected most frequently, followed by norovirus (23%), Salmonella spp. (20%), and rotavirus (15%). In 46% of the patients with Campylobacter spp. infection, the diagnosis was made solely by serology. More than one pathogen was found in seventeen (22%) patients. Simultaneous infection was significantly more likely in patients with rotavirus and salmonella infections (RR 3.6; 95% CI: 1.8-7.4; RR 2.5; 95%CI: 1.2-5.5). Length of hospital stay (median: 5.5 days) was independent of the pathogen, but was associated with coexisting medical conditions (OR 4,8; 95%CI:2,0-11,6). CONCLUSION: Known enteric pathogens were detected in 82% of adult patients who were hospitalized with acute gastroenteritis. We found that currently used culture-based methods may miss a substantial proportion of Campylobacter infections, and additional serological testing for Campylobacter should be considered. Viral infections emerged as an important cause of severe gastroenteritis in adults, and viral-bacterial co-infections in adults are probably underrecognized so far. The presence of coexisting medical conditions--but not the etiological agent--was a predictor for the duration of the hospital stay.

Molecular characterization of enteric viral agents from children in northern region of Ghana.

Viral gastrointestinal infections are among the most important causes of childhood morbidity and mortality, especially in non-industrialized countries. The objective of this study was the molecular characterization of rotaviruses, noroviruses, adenoviruses, astroviruses, and enteroviruses obtained from 367 children in the Northern Region of Ghana. One hundred and forty-two rotavirus-positive stool samples were examined. The most frequent type identified was G1P[8] occurring in 80% of the cases. Of 27 norovirus positive samples, 5 isolates belonged to genogroup I and 22 to genogroup II. Adenoviruses were detected in 73 samples; 23.3% of these belonged to genogroup F, 31.5% to D, 17.8% to A, 15.1% to C, and 12.3% to B. Astrovirus typing of 12 positive samples displayed a distribution into four different genotypes: five sequences clustered with AstV-8, four with AstV-2, two with AstV-5, and one with AstV-6. Twenty-three different enterovirus types were identified in 45 positive samples, coxsackievirus A24 being the most frequent pathogen (18%). This first, comprehensive molecular characterization of enteric viruses in northern Ghana provides baseline data for the molecular epidemiology of these pathogens and immunisation strategies. The available rotavirus vaccines cover the predominant G1P[8] type and would reduce substantially disease burden in that area.

Emergence of new norovirus variants on spring cruise ships and prediction of winter epidemics.

In June 2006, reported outbreaks of norovirus on cruise ships suddenly increased; 43 outbreaks occurred on 13 vessels. All outbreaks investigated manifested person-to-person transmission. Detection of a point source was impossible because of limited investigation of initial outbreaks and data sharing. The most probable explanation for these outbreaks is increased norovirus activity in the community, which coincided with the emergence of 2 new GGII.4 variant strains in Europe and the Pacific. As in 2002, a new GGII.4 variant detected in the spring and summer corresponded with high norovirus activity in the subsequent winter. Because outbreaks on cruise ships are likely to occur when new variants circulate, an active reporting system could function as an early warning system. Internationally accepted guidelines are needed for reporting, investigating, and controlling norovirus illness on cruise ships in Europe.

Identification of enterovirus serotypes by pyrosequencing using multiple sequencing primers.

Human enteroviruses (HEV) are considered as one of the major causes of central nervous system infections in pediatrics. They are currently classified into five species involving more than 60 officially recognized serotypes. This study describes a rapid molecular method, based on pyrosequencing of a VP1 fragment, for the identification of enterovirus serotypes. In order to do so, 200 isolates and clinical specimens that were first grouped into 62 different HEV serotypes using neutralization test, were analyzed by pyrosequencing. All serotypes were identified using the proposed method. Most of the isolates previously untypeable by classical procedures, as well as mixed enterovirus infections containing viruses belonging to different species, could also be determined using pyrosequencing. The present results give support to pyrosequencing as an efficient method of HEV genotyping.

Acute childhood diarrhoea in northern Ghana: epidemiological, clinical and microbiological characteristics.

BACKGROUND: Acute diarrhoea is a major cause of childhood morbidity and mortality in sub-Saharan Africa. Its microbiological causes and clinico-epidemiological aspects were examined during the dry season 2005/6 in Tamale, urban northern Ghana. METHODS: Stool specimens of 243 children with acute diarrhoea and of 124 control children were collected. Patients were clinically examined, and malaria and anaemia were assessed. Rota-, astro-, noro- and adenoviruses were identified by (RT-) PCR assays. Intestinal parasites were diagnosed by microscopy, stool antigen assays and PCR, and bacteria by culturing methods. RESULTS: Watery stools, fever, weakness, and sunken eyes were the most common symptoms in patients (mean age, 10 months). Malaria occurred in 15% and anaemia in 91%; underweight (22%) and wasting (19%) were frequent. Intestinal micro-organisms were isolated from 77% of patients and 53% of controls (P < 0.0001). The most common pathogens in patients were rotavirus (55%), adenovirus (28%) and norovirus (10%); intestinal parasites (5%) and bacteria (5%) were rare. Rotavirus was the only pathogen found significantly more frequently in patients than in controls (odds ratio 7.7; 95%CI, 4.2-14.2), and was associated with young age, fever and watery stools. Patients without an identified cause of diarrhoea more frequently had symptomatic malaria (25%) than those with diagnosed intestinal pathogens (12%, P = 0.02). CONCLUSION: Rotavirus-infection is the predominant cause of acute childhood diarrhoea in urban northern Ghana. The abundance of putative enteropathogens among controls may indicate prolonged excretion or limited pathogenicity. In this population with a high burden of diarrhoeal and other diseases, sanitation, health education, and rotavirus-vaccination can be expected to have substantial impact on childhood morbidity.

European multicenter evaluation of commercial enzyme immunoassays for detecting norovirus antigen in fecal samples.

A total of 2,254 fecal samples were tested in a European multicenter evaluation of commercially available norovirus antigen detection assays. Two commercial enzyme immunoassays, IDEIA Norovirus (Oxoid; Thermo Fisher Scientific, Ely, United Kingdom) and RIDASCREEN Norovirus (R-Biopharm, Darmstadt, Germany), were included in the evaluation, and their performance was compared with the results of reverse transcription-PCR (RT-PCR). Included in the evaluation were samples collected in sporadic cases of gastroenteritis, samples from outbreaks in which two or more samples were collected, well-characterized samples representing genotypes currently cocirculating within Europe, and samples collected from patients with gastroenteritis caused by a pathogen other than norovirus. The sensitivities and specificities of the IDEIA Norovirus and RIDASCREEN Norovirus assays were 58.93 and 43.81% and 93.91 and 96.37%, respectively, compared with RT-PCR. The sensitivities of both assays for outbreak investigations improved when six or more samples from an outbreak were examined. The IDEIA Norovirus assay exhibited reactivity to a broader range of norovirus genotypes than the RIDASCREEN Norovirus assay, which showed genotype-dependent sensitivities. The results indicate that, if used, these assays should serve as screening assays and the results should be confirmed by RT-PCR.

Field evaluation of a rota- and adenovirus immunochromatographic assay using stool samples from children with acute diarrhea in Ghana.

We evaluated the Rida Quick rotavirus/adenovirus Combi rapid immunochromatographic test (ICT) under field conditions with Ghanaian children with acute diarrhea. Compared to PCR results, sensitivities and specificities were 75% and 95% for rotavirus and 22% and 84% for adenovirus. In resource-poor settings, ICTs may help to overcome difficulties in the diagnosis of rotavirus infection.

A Toll-like receptor 7 single nucleotide polymorphism protects from advanced inflammation and fibrosis in male patients with chronic HCV-infection.

BACKGROUND/AIMS: HCV-infection leads to development of liver fibrosis, causing morbidity and mortality. Multiple factors influence the progression of fibrosis, including genetic factors. Since HCV is an RNA virus, a role for TLR7 in the immune response against HCV is likely. No systematic analysis of TLR7 single nucleotide polymorphisms (SNPs) has been published. METHODS: We sequenced TLR7 in 52 women and investigated SNPs with an allele frequency >5% in 807 patients with chronic HCV-infection by melting curve analysis. We analyzed the effect of TLR7 SNPs on grade of inflammation and stage of fibrosis as determined by liver biopsy. RESULTS: We detected five TLR7 SNPs, three of which showed a frequency >5%. One variant, c.1-120T>G, was more common in patients with no or little inflammation than in patients with grades 2-4 (10.7% vs. 6.1%; P=0.034). The variant was also enriched in patients with no or little fibrosis compared to those with higher stages (12.6% vs. 6.6%; P=0.005). The difference was fully attributable to male patients. CONCLUSIONS: This is the first analysis of TLR7 SNPs in patients with chronic HCV-infection. Our data suggest that the c.1-120G TLR7 allele offers protection from the development of inflammation and fibrosis in male patients with chronic HCV-infection.

Major outbreak of hepatitis A associated with orange juice among tourists, Egypt, 2004.

In 2004, a major outbreak of hepatitis A among tourists returning from Egypt involved 351 case-patients from 9 European countries who were infected with a single strain (genotype 1 b). The case-control study identified orange juice as the most likely infection vehicle. Vaccination against hepatitis A virus is strongly recommended before travel to disease-endemic areas.

Molecular epidemiological studies show that hepatitis A virus is endemic among active homosexual men in Europe.

Large outbreaks of hepatitis A have occurred in Denmark, Germany, the Netherlands, Norway, Spain, Sweden, and the United Kingdom during the period 1997-2005 affecting homosexual men. A collaborative study was undertaken between these countries to determine if the strains involved in these hepatitis A outbreaks were related genetically. The N-terminal region of VP1 and the VP1/P2A region of the strains were sequenced and compared. The majority of the strains found among homosexual men from the different European countries formed a closely related cluster, named MSM1, belonging to genotype IA. Different HAV strains circulated among other risk groups in these countries during the same period, indicating that specific strains were circulating among homosexual men exclusively. Similar strains found among homosexual men from 1997 to 2005 indicate that these HAV strains have been circulating among homosexual men for a long time. The homosexual communities are probably too small within the individual countries to maintain HAV in their population over time, whereas the homosexual communities across Europe are probably sufficiently large to sustain continued circulation of homologous HAV strains for years resulting in an endemic situation among homosexual men.

Detection of Norovirus genogroup I and II by multiplex real-time RT- PCR using a 3'-minor groove binder-DNA probe.

BACKGROUND: Due to an increasing number of norovirus infections in the last years rapid, specific, and sensitive diagnostic tools are needed. Reverse transcriptase-polymerase chain reactions (RT-PCR) have become the methods of choice. To minimize the working time and the risk of carryover contamination during the multi-step procedure of PCR the multiplex real-time RT-PCR for the simultaneous detection of genogroup I (GI) and II (GII) offers advantages for the handling of large amounts of clinical specimens. METHODS: We have developed and evaluated a multiplex one-tube RT-PCR using a combination of optimized GI and GII specific primers located in the junction between ORF1 and ORF2 of the norovirus genome. For the detection of GI samples, a 3'-minor groove binder-DNA probe (GI-MGB-probe) were designed and used for the multiplex real-time PCR. RESULTS: Comparable results to those of our in-house nested PCR and monoplex real-time-PCR were only obtained using the GI specific MGB-probe. The MGB-probe forms extremely stable duplexes with single-stranded DNA targets, which enabled us to design a shorter probe (length 15 nucleotides) hybridizing to a more conserved part of the GI sequences. 97% of 100 previously norovirus positive specimens (tested by nested PCR and/or monoplex real-time PCR) were detected by the multiplex real-time PCR. A broad dynamic range from 2 x 10(1) to 2 x 10(7) genomic equivalents per assay using plasmid DNA standards for GI and GII were obtained and viral loads between 2.5 x 10(2) and 2 x 10(12) copies per ml stool suspension were detected. CONCLUSION: The one-tube multiplex RT real-time PCR using a minor groove binder-DNA probe for GI is a fast, specific, sensitive and cost-effective tool for the detection of norovirus infections in both mass outbreaks and sporadic cases and may have also applications in food and environmental testing.

An outbreak of Norovirus infection affecting an Austrian nursing home and a hospital.

On November 9, 2004, a resident in a nursing home experienced a severe episode of vomiting in the dining room, in the presence of most of the other residents and members of staff. Following that episode, 17 of the 23 (73.9%) other residents and 7 of the 18 (38.9%) staff members fell ill with diarrhea and/or vomiting in the period up to November 17. A second cluster of gastroenteritis occurred between November 11 and 28, 2004, in a nearby hospital to which eight cases among the nursing home residents had been referred. Ten of 46 (21.7%) other hospital patients and 18 of 60 (30%) members of the hospital staff suffered from vomiting or diarrhea. Epidemiological and laboratory investigations proved a causal relationship between the two institutional clusters of short-lived gastroenteritis related by time and place, and identified Norovirus genotype GGII.4 (Jamboree-like) as the causative pathogen. Control measures for Norovirus, based on epidemiological and clinical features of the outbreak, were effectively implemented in the nursing home without waiting for virological confirmation. At the hospital, specific measures were not implemented until after virological confirmation of the causative agent, by which time 16 cases had already occurred. In a suspected Norovirus outbreak it is of great importance -- especially within closed and semiclosed settings -- to implement control measures as soon as possible, even before laboratory confirmation of the agent.