J Gray

Changes in Causes of Acute Gastroenteritis in the United Kingdom Over 15 Years: Microbiologic Findings From 2 Prospective, Population-Based Studies of Infectious Intestinal Disease

BACKGROUND Large-scale, prospective studies of infectious intestinal disease (IID) in developed countries are uncommon. Two studies of IID incidence and etiology have been conducted in the United Kingdom: the Infectious Intestinal Disease Study in England (IID1) in 1993-1996 and the Second Study of Infectious Intestinal Disease in the Community (IID2) in 2008-2009. We examined changes in etiology and diagnostic yield of IID cases over 15 years. METHODS Fecal samples submitted by IID cases were examined for a range of bacterial, viral, and protozoal pathogens using traditional and molecular microbiological methods. We calculated the percentage of specimens positive for each organism based on traditional methods and on traditional and molecular methods combined. We compared the distributions of organisms in the 2 studies. RESULTS For pathogens investigated in both studies, 40% of fecal samples submitted by cases in IID2 were positive compared with 28% in IID1. Viruses were most frequent among community cases in IID2. Campylobacter was the most common bacterial pathogen among cases presenting to healthcare. Major differences between the 2 studies were increases in the detection of norovirus and sapovirus and a decline Salmonella. CONCLUSIONS Most fecal specimens were negative for the pathogens tested in both studies, so new strategies are needed to close the diagnostic gap. Among known pathogens, effective control of norovirus, rotavirus, and Campylobacter remain high priorities. The reduction in nontyphoidal salmonellosis demonstrates the success of Europe-wide control strategies, notably an industry-led Salmonella control program in poultry in the United Kingdom.

Rotavirus Surveillance in Europe, 2005–2008: Web-Enabled Reporting and Real-Time Analysis of Genotyping and Epidemiological Data

BACKGROUND The first European rotavirus surveillance network, EuroRotaNet, comprising 16 laboratories in 15 European countries, has been established. METHODS Fecal samples from gastroenteritis cases positive for group A rotavirus antigen were collected from multiple European countries from 2005 to mid-2008 and were subjected to G and P genotyping. Epidemiological data collected included age, sex, geographical location, setting, dates of onset and sample collection, and clinical symptoms. RESULTS A total of 8879 rotavirus-positive samples were characterized: 2129 cases were from the 2005-2006 season, 4030 from the 2006-2007 season, and 2720 from the ongoing 2007-2008 season. A total of 30 different G and P type combinations of strains circulated in the region from 2005 through 2008. Of these strains, 90% had genotypes commonly associated with human infections-G1P[8], G2P[4], G3P[8], G4P[8], and G9P[8]-and 1.37% represented potential zoonotic introductions. G1P[8] remained the most prevalent genotype in Europe as a whole, but the incidence of infection with G1P[8] rotavirus strains was <50% overall, and all 3 seasons were characterized by a significant diversity of cocirculating strains. The peak incidence of rotavirus infection occurred from January through May, and 81% of case patients were aged <2.5 years. Conclusions. Data gathered through EuroRotaNet will provide valuable background information on the rotavirus strain diversity in Europe before the introduction of rotavirus vaccines, and the network will provide a robust method for surveillance during vaccine implementation.

Norovirus in the hospital setting: virus introduction and spread within the hospital environment

Norovirus (NoV) strains were collected over a four-month period during 2009-2010 from hospitalised patients with symptoms of gastroenteritis. These were characterised in order to estimate how many strains were introduced into the hospital from the community. In addition, environmental swabbing was performed after clinical cleaning of bays or wards accommodating infected patients. This was performed in order to assess the efficiency of cleaning and identify any NoV contamination in the environment. A total of eight distinct genetic clusters of NoV GII-4 genotype were identified during the four-month period, with some wards experiencing multiple outbreaks with different GII-4 strains during the season. NoV was detected from 31.4% of environmental swabs post cleaning. Notes trolleys, computer keyboards, soap and alcohol dispensers, blood pressure equipment, pulse oximeters and tympanic thermometers were identified as NoV reservoirs but contamination was also found on surfaces around the bedside environment, and furniture, fixtures and fittings associated with toilets and shower rooms. The combination of detailed virus characterisation and environmental swabbing is a powerful tool for infection control audits to determine the size and scope of an outbreak and to monitor the efficiency of clinical cleaning.

Infant morbidity in an Indian slum birth cohort

Objective: To establish incidence rates, clinic referrals, hospitalisations, mortality rates and baseline determinants of morbidity among infants in an Indian slum. Design: A community-based birth cohort with twice-weekly surveillance. Setting: Vellore, South India. Subjects: 452 newborns recruited over 18 months, followed through infancy. Main outcome measures: Incidence rates of gastrointestinal illness, respiratory illness, undifferentiated fever, other infections and non-infectious morbidity; rates of community-based diagnoses, clinic visits and hospitalisation; and rate ratios of baseline factors for morbidity. Results: Infants experienced 12 episodes (95% confidence interval (CI) 11 to 13) of illness, spending about one fifth of their infancy with an illness. Respiratory and gastrointestinal symptoms were most common with incidence rates (95% CI) of 7.4 (6.9 to 7.9) and 3.6 (3.3 to 3.9) episodes per child-year. Factors independently associated with a higher incidence of respiratory and gastrointestinal illness were age (3–5 months), male sex, cold/wet season and household involved in beedi work. The rate (95% CI) of hospitalisation, mainly for respiratory and gastrointestinal illness, was 0.28 (0.22 to 0.35) per child-year. Conclusions: The morbidity burden due to respiratory and gastrointestinal illness is high in a South Indian urban slum, with children ill for approximately one fifth of infancy, mainly with respiratory and gastrointestinal illnesses. The risk factors identified were younger age, male sex, cold/wet season and household involvement in beedi work.

Rotavirus gastroenteritis and central nervous system (CNS) infection: characterization of the VP7 and VP4 genes of rotavirus strains isolated from paired fecal and cerebrospinal fluid samples from a child with CNS disease.

ABSTRACT Rotavirus RNA was detected in the cerebrospinal fluid (CSF) of a child with central nervous system disease symptoms associated with rotavirus gastroenteritis. The rotavirus isolates from the fecal and CSF samples were genotyped as G1P[8]. Sequence analysis of the VP7 and VP4 proteins derived from the fecal and CSF samples were remarkably similar to each other and to G1P[8] rotavirus strains commonly circulating in the community and associated with gastroenteritis.

Surveillance of human rotaviruses in 2007–2011, Hungary: Exploring the genetic relatedness between vaccine and field strains

BACKGROUND The availability of rotavirus vaccines has resulted in an intensification of post vaccine strain surveillance efforts worldwide to gain information on the impact of vaccines on prevalence of circulating rotavirus strains. OBJECTIVES In this study, the distribution of human rotavirus G and P types in Hungary is reported. In addition, the VP4 and VP7 genes of G1P[8] strains were sequenced to monitor if vaccine-derived strains were introduced and/or some strains/lineages were selected against. STUDY DESIGN The study was conducted in 8 geographic areas of Hungary between 2007 and 2011. Rotavirus positive stool samples were collected from diarrheic patients mostly <5 years of age. Viral RNA was amplified by multiplex genotyping RT-PCR assay, targeting the medically most important G and P types. When needed, sequencing of the VP7 and VP4 genes was performed. RESULTS In total, 2380 strains were genotyped. During the 5-year surveillance we observed the dominating prevalence of genotype G1P[8] (44.87%) strains, followed by G4P[8] (23.4%), G2P[4] (14.75%) and G9P[8] (6.81%) genotypes. Uncommon strains were identified in a low percentage of samples (4.12%). Phylogenetic analysis of 318 G1P[8] strains identified 55 strains similar to the Rotarix strain (nt sequence identities; VP7, up to 97.9%; VP4, up to 98.5%) although their vaccine origin was unlikely. CONCLUSIONS Current vaccines would have protected against the majority of identified rotavirus genotypes. A better understanding of the potential long-term effect of vaccine use on epidemiology and evolutionary dynamics of co-circulating wild type strains requires continuous strain surveillance.

Comparison of Age-Stratified Seroprevalence of Antibodies against Norovirus GII in India and the United Kingdom

Noroviruses are a common cause of gastroenteritis worldwide, but outbreaks appear to be more common in industrialized countries than in developing countries, possibly reflecting differences in exposure and immunity. In this study, age-stratified sera from India and UK populations were analysed for the presence of norovirus-genogroup II specific IgG by a time resolved immunofluorescence assay and relative levels of antibodies in the two populations were compared. Antibody levels were higher among all age groups in India than in UK and increased with age in India, whereas in the UK, levels of antibody decreased in adulthood. These results indicate different patterns of exposure to noroviruses in the two countries.

Investigating the link between the presence of enteroaggregative Escherichia coli and infectious intestinal disease in the United Kingdom, 1993 to 1996 and 2008 to 2009.

There are an estimated 17 million human diarrhoea cases annually in the United Kingdom. In 2008 and 2009, enteroaggregative E. coli (EAEC) were identified in 1.9% of stools. However, it remains unclear whether there is a causal link between presence of EAEC and disease. This study used bacterial load, the presence of co-infections and demographic data to assess if EAEC was independently associated with intestinal infectious disease. Quantitative real-time PCR data (Ct values) generated directly from stool specimens for several pathogen targets were analysed to identify multiple pathogens, including EAEC, in the stools of cases and healthy controls. Sensitivity and specificity using Ct value (60% and 60%) was not useful for identifying cases or controls, but an independent association between disease and EAEC presence was demonstrated: multivariate logistic regression for EAEC presence (odds ratio: 2.41; 95% confidence interval: 1.78–3.26; p<0.001). The population-attributable fraction was 3.3%. The group of bacteria known as EAEC are associated with gastrointestinal disease in at least half of the cases with EAEC positive stools. We conclude that the current definition of EAEC, by plasmid gene detection, includes true pathogens as well as non-pathogenic variants.

Universal extraction method for gastrointestinal pathogens.

A universal stool extraction method for recovery of nucleic acids (NAs) from gastrointestinal pathogens was developed to support rapid diagnostics for the London 2012 Olympics. The method involved mechanical disruption (bead beating) of the stools, followed by automated extraction and detection using real-time PCR. This method had been used extensively in the Second Infectious Intestinal Disease Study (IID2) for the isolation of NA from bacteria and parasites (and was effective for the robust recovery of Cryptosporidium spp.) but had not been used for enteric viruses. To ensure this method was universally suitable, panels of samples known to contain target bacteria, viruses or parasites were processed in triplicate using the pre-treatment method routinely used for each target and the new extraction method (bead beating). The extracts were tested using real-time PCR and the cycle threshold values were compared. The results from this study showed that bead beating improved yields for the bacterial and parasitic targets and was suitable for the viral targets. The implementation of this universal method should confer cost- and time-saving benefits and streamline the processes required for the characterization of an array of pathogens from faecal samples.

Genetic characterization of Bulgarian rotavirus isolates and detection of rotavirus variants: challenges for the rotavirus vaccine program?

Annually 20–70% of all hospital admissions and 20% of fatal diarrhea cases among children less than 5 years of age occur due to severe rotavirus diarrhea. Universal immunization is the major strategy aimed at controlling rotavirus infection. The main objective of the present study was to elucidate the evolutionary relationships of the most common rotavirus strains co‐circulating in Bulgaria. The sequence and phylogenetic analysis revealed strain diversity and circulation of different rotavirus variants belonging to a single genotype. A mutated G4P[8] strain with the insertion of an asparagine residue in position 76; G2, G9, and G1 variants with amino acid substitutions in the antigenic regions A, B, and/or C were all identified in this study in the absence of an immunization program. Rotavirus strain surveillance in both the pre‐ and post‐vaccine eras is of increasing importance in order to assess the effectiveness of the rotavirus vaccines for protection against disease associated with a diverse population of rotavirus strains. J. Med. Virol. 83:348–356, 2011.