Astrovirus, adenovirus, and rotavirus in hospitalized children: prevalence and association with gastroenteritis

Presence and Diversity of Different Enteric Viruses in Wild Norway Rats (Rattus norvegicus)

Rodents are common reservoirs for numerous zoonotic pathogens, but knowledge about diversity of pathogens in rodents is still limited. Here, we investigated the occurrence and genetic diversity of enteric viruses in 51 Norway rats collected in three different countries in Europe. RNA of at least one virus was detected in the intestine of 49 of 51 animals. Astrovirus RNA was detected in 46 animals, mostly of rat astroviruses. Human astrovirus (HAstV-8) RNA was detected in one, rotavirus group A (RVA) RNA was identified in eleven animals. One RVA RNA could be typed as rat G3 type. Rat hepatitis E virus (HEV) RNA was detected in five animals. Two entire genome sequences of ratHEV were determined. Human norovirus RNA was detected in four animals with the genotypes GI.P4-GI.4, GII.P33-GII.1, and GII.P21. In one animal, a replication competent coxsackievirus A20 strain was detected. Additionally, RNA of an enterovirus species A strain was detected in the same animal, albeit in a different tissue. The results show a high detection rate and diversity of enteric viruses in Norway rats in Europe and indicate their significance as vectors for zoonotic transmission of enteric viruses. The detailed role of Norway rats and transmission pathways of enteric viruses needs to be investigated in further studies.

Adenovirus Infection Is Predicted by Prolonged Duration of Diarrhea among Rotavirus-Vaccinated Children below Five Years of Age in Mwanza, Tanzania

Diarrhea is the commonest cause of morbidity and mortality in many resource-limited countries including Tanzania among children below five years of age. A significant number of diarrhea cases associated with severe dehydration are still being reported among children despite five years of rotavirus vaccine implementation in Tanzania necessitating the need to investigate other causes of diarrhea in this population. This study is aimed at determining the prevalence of human adenovirus infection and associated factors among rotavirus-vaccinated children with acute diarrhea in Mwanza, Tanzania. A cross-sectional study was conducted from June to August 2017 involving 137 children less than two years of age admitted with acute diarrhea in the health facilities located in Mwanza, Tanzania. Sociodemographic and other relevant information were collected using standardized rotavirus surveillance tool adopted from WHO. Stool specimens were collected and tested for human adenovirus antigen using immunochromatographic tests. Data were analyzed by using STATA version 13. The median age of enrolled children was 12 (IQR 8-17) months. The prevalence of human adenovirus was found to be 46 (33.6%, 95% CI: 25-41). By multivariable logistic regression analysis, only prolonged duration of diarrhea (OR: 1.619, 95% CI: 1.142-2.295, p = 0.007) was found to predict human adenovirus infection among rotavirus-vaccinated children with acute diarrhea. A significant proportion of rotavirus-vaccinated children with prolonged acute diarrhea have adenovirus infection. There is a need to consider other viral pathogens as potential cause of diarrhea especially in this postrotavirus vaccination period.

QMRA of adenovirus in drinking water at a drinking water treatment plant using UV and chlorine dioxide disinfection

According to the Dutch Drinking Water Act of 2011, Dutch drinking water suppliers must conduct a Quantitative Microbial Risk Assessment (QMRA) for infection by the following index pathogens: enterovirus, Campylobacter, Cryptosporidium and Giardia at least once every four years in order to assess the microbial safety of drinking water. The health-based target for safe drinking water is set at less than one infection per 10 000 persons per year. At Evides Water Company, concern has arisen whether their drinking water treatment, mainly based on UV inactivation and chlorine dioxide, reduces levels of adenovirus (AdV) sufficiently. The main objective was, therefore, to conduct a QMRA for AdV. Estimates of the AdV concentrations in source water were based on enumeration of total AdV by integrated cell culture PCR (iccPCR), most probable number PCR (mpnPCR) and quantitative PCR (qPCR), and on enumeration of AdV40/41 by mpnPCR and qPCR. AdV40/41 represents a large fraction of total AdV and only a small fraction of AdV is infectious (1/1700). By comparison of literature data and plant scale data, somatic coliphages appeared a good, conservative indicator for AdV disinfection by UV irradiation. Similarly, bacteriophage MS2 appeared to be a good, conservative indicator for disinfection by chlorine dioxide. Literature data on the efficiency of chlorine dioxide disinfection were fitted with the extended HOM model. Chlorine dioxide disinfection at low initial concentrations (0.05-0.1 mg/l) was found to be the major treatment step, providing sufficient treatment on its own for compliance with the health-based target. UV disinfection of AdV at 40 mJ/cm² or 73 mJ/cm² was insufficient without chlorine dioxide disinfection.

Healthcare-Associated Viral Infections: Considerations for Nosocomial Transmission and Infection Control

Nosocomial and healthcare-associated viral infections are major contributors to patient morbidity and mortality, prolonged hospitalization, and increased healthcare costs in all pediatric age groups. Healthcare workers are also at risk of acquiring nosocomial viral infections, affecting their own health, as well as facilitating spread of the infection to other patients, their family, and the community. Healthcare-associated viral infections may occur in a variety of healthcare settings, including clinics, emergency centers, urgent care centers, procedure suites, operating rooms, hospital wards, nurseries, and intensive care units. In addition, non-patient care areas, such as the cafeteria, waiting areas, and playrooms may also be a source of viral infections that can spread in the healthcare setting. These infections may be device-related or transmitted via blood products or organ donation and respiratory droplets, through food including human milk, person to person, or via air ducts, fomites, and surfaces. They most commonly involve the respiratory and gastrointestinal tracts; however, all organ systems may potentially be involved. Both DNA and RNA viruses, either common or exotic, may contribute to healthcare-associated viral infections. Advances in molecular viral diagnostics have enabled rapid detection and routine surveillance for viral infections and now allow early identification of viruses. Prompt identification allows timely containment measures to minimize transmission to other patients or healthcare workers and avoids hospital, community, and global outbreaks.

Co-circulation of classic and novel astrovirus strains in patients with acute gastroenteritis in Germany

OBJECTIVES

In order to analyze the molecular epidemiology of human astroviruses (HAstV) in Germany, a retrospective long-term study was performed to characterize circulating human astrovirus in patients with acute gastroenteritis in Germany.

METHODS

A total of 2877 stool samples, collected between January 2010 and December 2015 from sporadic cases and outbreaks of acute gastroenteritis were retrospectively analyzed for astrovirus. A two-step PCR algorithm was developed and used to identify and characterize human astrovirus infections.

RESULTS

Overall, 143 samples were astrovirus-positive (5.0%). Astrovirus infection was most frequently detectable in samples from children of 3-4 years (15%) followed by children of 1-2 years (8.6%), detection rates in adults were lower (1%-3.6%). A high number (71.3%) of co-infections, mainly with noro- or rotaviruses, were identified. Genotyping revealed that at least ten genotypes from all four human MAstV species were circulating in the study population. HAstV-1 was predominant in different age groups. Novel HAstV (MLB and VA genotypes) were also circulating in Germany.

CONCLUSION

Our findings give new insights into the circulation and genetic diversity of human astroviruses in patients with acute gastroenteritis. The novel HAstV-MLB and -VA genotypes could be characterized firstly in Germany while the analysis showed that these viruses have been dispersed in Germany since 2011 as a causative agent of acute gastroenteritis.

A generalized dose-response relationship for adenovirus infection and illness by exposure pathway

Adenoviruses are found everywhere in the environment, and cause various health problems including symptoms of enteric illness, and respiratory illness. Despite their significance to public health, few studies have addressed the health risks associated with exposure to adenovirus. Human challenge studies have been published for a few adenoviruses, which involved exposure through oral ingestion, inhalation, intranasal and intraocular droplet inoculation. Nothwithstanding the different symptoms resulting from such exposures, infection can be defined as colonization of a corresponding mucosa. A two-level dose-response model was developed to describe the distributions of infectivity and pathogenicity in various challenge studies of adenovirus, incorporating differences in inoculation route as shift in average infectivity and pathogenicity. This dose-response model can be used to make predictions for the infectivity of adenovirus, specific to any of the four studied inoculation methods. The generalized adenovirus dose-response relationship for infection and acute illness takes into account variation in infectivity and/or pathogenicity across adenovirus types, as well as uncertainty due to limited data.

Gastrointestinal Infections

Gastrointestinal infections in the immunocompromised host are caused by the common bacterial, viral, fungal, and parasitic agents that also cause infections in the immunocompetent host. Of special consideration is that immunocompromised patients may be at increased risk for infection or disease severity and by pathogens not seen in the competent host. This chapter reviews the various agents, risk factors, and diagnostic approaches to detect gastrointestinal infections in this patient population.

Gastrointestinal Infections

Establishing a specific etiology for gastrointestinal infections can be challenging because of the common clinical features and wide variety of causative microorganisms. In many cases, the etiologic agent cannot be determined using traditional diagnostic methods and may result in unnecessary antibiotic use or prolonged periods of illness. Molecular tests provide many advantages over traditional laboratory methods but, with the exception of a few analytes, are still largely in the developmental phase for gastrointestinal pathogens and are not widely used. The main advantages of molecular tests include increased sensitivity and the ability to detect agents which will not grow in culture. To test for all possible gastrointestinal pathogens at one time would require a large panel that would include a variety of bacterial, viral and parasitic agents. Challenges inherent in developing diagnostic molecular panels include ensuring that all variants of a particular microorganism can be detected as well as the rapid evolution of pathogens. In this chapter, the diagnostic merit of molecular tests as well as available tests will be presented for the major groups of gastrointestinal pathogens.

Diagnosis of viral gastroenteritis in children: interpretation of real-time PCR results and relation to clinical symptoms

Molecular methods such as real-time polymerase chain reaction (PCR) are rapidly replacing traditional tests to detect fecal viral pathogens in childhood diarrhea. This technique has now increased the analytical sensitivity so drastically that positive results are found in asymptomatic children, leading to complex interpretation of real-time PCR results and difficult distinction between asymptomatic shedding and etiological cause of disease. We performed a review of the literature including pediatric studies using real-time PCR and a minimal inclusion period of one year to exclude bias by seasonality. We searched for studies on rotavirus, norovirus, adenovirus, astrovirus, and sapovirus, known to be the most common viruses to cause gastroenteritis in the pediatric population. For these viruses, we summarized the detection rates in hospitalized and community-based children with clinical symptoms of gastroenteritis, as well as subjects with asymptomatic viral shedding. Moreover, insight is given into the different viral sero- and genotypes causing pediatric gastroenteritis. We also discuss the scoring systems for severity of disease and their clinical value. A few published proposals have been made to improve the clinical interpretation of real-time PCR results, which we recapitulate and discuss in this review. We propose using the semi-quantitative measure of real-time PCR, as a surrogate for viral load, in relation to the severity score to distinguish asymptomatic viral shedding from clinically relevant disease. Overall, this review provides a better understanding of the scope of childhood gastroenteritis, discusses a method to enhance the interpretation of real-time PCR results, and proposes conditions for future research to enhance clinical implementation.

Incubation periods of viral gastroenteritis: a systematic review

BACKGROUND

Accurate knowledge of incubation period is important to investigate and to control infectious diseases and their transmission, however statements of incubation period in the literature are often uncited, inconsistent, and/or not evidence based.

METHODS

In a systematic review of the literature on five enteric viruses of public health importance, we found 256 articles with incubation period estimates, including 33 with data for pooled analysis.

RESULTS

We fit a log-normal distribution to pooled data and found the median incubation period to be 4.5 days (95% CI 3.9-5.2 days) for astrovirus, 1.2 days (95% CI 1.1-1.2 days) for norovirus genogroups I and II, 1.7 days (95% CI 1.5-1.8 days) for sapovirus, and 2.0 days (95% CI 1.4-2.4 days) for rotavirus.

CONCLUSIONS

Our estimates combine published data and provide sufficient quantitative detail to allow for these estimates to be used in a wide range of clinical and modeling applications. This can translate into improved prevention and control efforts in settings with transmission or the risk of transmission.

Etiology of viral gastroenteritis in children <5 years of age in the United States, 2008-2009

BACKGROUND

Although rotavirus and norovirus cause nearly 40% of severe endemic acute gastroenteritis (AGE) in children <5 years of age in the United States, there are limited data on the etiologic role of other enteric viruses in this age group.

METHODS

We conducted active population-based surveillance in children presenting with AGE to hospitals, emergency departments, and primary care clinics in 3 US counties. Stool specimens from these children and from age-matched healthy controls collected between October 2008 and September 2009 were tested for enteric adenovirus, astrovirus, sapovirus, parechovirus, bocavirus, and aichivirus. Typing was performed by sequencing and phylogenetic analysis.

RESULTS

Adenovirus, astrovirus, sapovirus, parechovirus, bocavirus, and aichivirus were detected in the stool specimens of 11.8%, 4.9%, 5.4%, 4.8%, 1.4%, and 0.2% of patients with AGE and 1.8%, 3.0%, 4.2%, 4.4%, 2.4%, and 0% of healthy controls, respectively. Adenovirus (type 41), astrovirus (types 1, 2, 3, 4, and 8), sapovirus (genogroups I and II), parechovirus (types 1, 3, 4, and 5), and bocavirus (types 1, 2, and 3) were found cocirculating.

CONCLUSIONS

Adenovirus, astrovirus, and sapovirus infections were detected in 22.1% of the specimens from children <5 years of age who had medical visits for AGE and tested negative for rotavirus and norovirus. No causal role for parechovirus and bocavirus was found.

Multicenter study on season of birth and celiac disease: evidence for a new theoretical model of pathogenesis

OBJECTIVE

To investigate whether season of birth is associated with celiac disease (CD).

STUDY DESIGN

We performed a medical record review of 1964 patients with biopsy-proven CD at 3 teaching hospitals (2 pediatric centers and 1 adult center) between 2000 and 2010. The first positive small intestinal biopsy result defined age of diagnosis. The observed proportions of births in each season (spring [March-May], summer [June-August], fall [September-November], and winter [December-February]) were compared with the expected proportions using binomial probability tests.

RESULTS

The mean age at diagnosis was 9.8 ± 5.0 years in the 2 pediatric centers and 43.6 ± 15.8 years in the adult center. The cohort was predominately female (69%). Overall, more patients were born in spring (27%) than in any other season: summer (25%), fall (25%), and winter (23%). In patients diagnosed before age 15 years, the spring birth excess was present in boys (33%; P = .0005), but not in girls (26%; P = .43). The sex difference in season of birth was less striking in patients with CD diagnosed at age ≥15 years.

CONCLUSION

Season of birth is an environmental risk factor for CD, particularly in boys diagnosed before age 15 years. The results are consistent with a new theoretical model that integrates potential environmental factors (eg, gluten introduction, ultraviolet-B exposure, vitamin D status) and acute viral gastrointestinal infections in early childhood.

Detection and molecular characterization of adenoviruses in Korean children hospitalized with acute gastroenteritis

Human adenoviruses (HAdVs) are an important cause of acute gastroenteritis in children. However, few studies on the epidemiology or types of HAdVs associated with acute gastroenteritis have been conducted in Korea. Therefore, in the present study, the incidence of HAdV in 2064 stool samples from Korean children hospitalized with acute gastroenteritis (2004-2006) was assessed and the types of viruses present determined. Polymerase chain reaction, sequencing, and phylogenic analyses revealed that 113 samples (5.5%) were HAdV-positive. While HAdVs were mainly detected during July to October, no seasonal difference between the enteric and non-enteric viruses in the incidence of HAdV was observed. HAdV-41 and HAdV-40 were found in 54 (47.8%) and 3 (2.6%) HAdV-positive samples, respectively. HAdV-3, HAdV-7, HAdV-2, HAdV-31, HAdV-4, and HAdV-37 were detected in 11 (9.7%), 5 (4.4%), 2 (1.7%), 2 (1.7%), 1 (0.8%), and 1 (0.8%) of sample(s), respectively. Thus, not only enteric, but also non-enteric, HAdVs may play an important role in acute gastroenteritis in Korean children.

The role of prolonged viral gastrointestinal infections in the development of immunodeficiency-related enteropathy

Patients with primary immunodeficiencies are prone to develop enteropathy of unknown pathogenesis. We hypothesize that ineffective clearance of gastrointestinal pathogens, particularly viruses, in combination with defective immune regulation may cause inflammatory enteropathy in certain immunodeficient hosts. We reviewed publications related to prolonged enteric viral infection, immunodeficiency, and the subsequent development of inflammatory enteropathy. Prolonged infection with especially enteroviral infections was reported more often in immunocompromised hosts than in healthy individuals. Protracted enteric viral shedding was not always associated with the presence or duration of gastrointestinal symptoms. The development of immunodeficiency-associated enteropathy after prolonged viral infections was described in sporadic cases. Clinical consequences of viral gut infections in immunocompromised hosts comprise isolation issues and supportive care. Prospective studies in cohorts of immunodeficient patients are required to study the impact of prolonged enteric viral replication with respect to the pathogenesis of non-infectious enteropathy.

Diarrhea etiology in a pediatric emergency department: a case control study

BACKGROUND

The etiology of childhood diarrhea is frequently unknown.

METHODS

We sought Aeromonas, Campylobacter, Escherichia coli O157:H7, Pleisiomonas shigelloides, Salmonella, Shigella, Vibrio, and Yersinia (by culture), adenoviruses, astroviruses, noroviruses, rotavirus, and Shiga toxin-producing E. coli (STEC; by enzyme immunoassay), Clostridium difficile (by cytotoxicity), parasites (by microscopy), and enteroaggregative E. coli (EAEC; by polymerase chain reaction [PCR] analysis) in the stools of 254 children with diarrhea presenting to a pediatric emergency facility. Age- and geographic-matched community controls without diarrhea (n = 452) were similarly studied, except bacterial cultures of the stool were limited only to cases.

RESULTS

Twenty-nine (11.4%) case stools contained 13 Salmonella, 10 STEC (6 O157:H7 and 4 non-O157:H7 serotypes), 5 Campylobacter, and 2 Shigella. PCR-defined EAEC were present more often in case (3.2%) specimens than in control (0.9%) specimens (adjusted odds ratio [OR], 3.9; 95% confidence interval [CI], 1.1-13.7), and their adherence phenotypes were variable. Rotavirus, astrovirus, and adenovirus were more common among cases than controls, but both groups contained noroviruses and C. difficile at similar rates. PCR evidence of hypervirulent C. difficile was found in case and control stools; parasites were much more common in control specimens.

CONCLUSIONS

EAEC are associated with childhood diarrhea in Seattle, but the optimal way to identify these agents warrants determination. Children without diarrhea harbor diarrheagenic pathogens, including hypervirulent C. difficile. Our data support the importance of taking into account host susceptibility, microbial density, and organism virulence traits in future case-control studies, not merely categorizing candidate pathogens as being present or absent.

Analysis of the aetiology of diarrhoea in outpatients in 2007, Henan province, China

The purpose of this study was to determine the aetiology of acute diarrhoea and improve knowledge of gastrointestinal pathogens in China. Faecal specimens from 1526 outpatients with diarrhoea were collected from 20 hospitals in Henan province and the prevalence of seven bacterial and five viral diarrhoeagenic pathogens were determined. Bacterial pathogens were recovered from 279/1526 (18·3%) stool specimens and viral pathogens were detected in 178/1526 (11·7%) stool specimens. The top five pathogenic species were diarrhoeagenic E. coli (n = 140, 9·2%), rotavirus (n = 79, 5·2%), Shigella spp. (n = 69, 4·5%), Salmonella spp. (n = 66, 4·3%) and norovirus (n = 56, 3·7%). The prevalence of pathogens showed correlation with age, season and clinical symptoms. Several dominant serotypes were identified in Shigella and Salmonella isolates, and high prevalence of multiple drug-resistant isolates was observed in both species. This important information will have a significant effect on public health policy development and resource prioritization practices.

Nosocomial rotavirus infections: a meta-analysis

BACKGROUND AND OBJECTIVES

Nosocomial rotavirus (nRV) infections represent an important part of rotavirus (RV)-associated morbidity. The incidence of nRV influences the estimated total RV disease burden, an important determinant of cost-effectiveness of RV vaccination programs. Our aim is to summarize the existing evidence and produce reliable estimates of nRV incidence, in pediatric settings in Europe and North America.

METHODS

We searched electronic databases for studies on nRV incidence among pediatric inpatients. To ascertain complete case reporting, only studies describing active nRV surveillance in their methodology were included. Random effects meta-analysis was performed. Meta-regression was used to obtain results adjusted for important study characteristics.

RESULTS

Twenty surveillance studies met the quality criteria for inclusion. The pooled unadjusted nRV incidence was 2.9 per 100 hospitalizations (95% confidence interval [CI]: 1.6-4.4). Incidence was significantly influenced by studies' seasonality-months (RV epidemic season only or year-round) and the age range of included patients. Highest nRV incidence was found for children <2 years of age, hospitalized during the epidemic months (8.1/100 hospitalizations; 95% CI: 6.4-9.9). The adjusted year-round nRV incidence estimate without age restriction was 0.4/100 hospitalizations (95% CI: 0.1-2.1) and 0.7 (95% CI: 0.0-1.8) for children <5 years of age.

CONCLUSIONS

This is the first meta-analysis to summarize results of surveillance studies on nRV incidence. nRV is an important problem among hospitalized infants during the winter months. The lower season and age-adjusted nRV incidence estimate seems more appropriate for application in population-based burden of disease analysis.

Epidemiology of astrovirus infection in children

Human astrovirus (HAstV) is a major cause of acute diarrhea among children, resulting in outbreaks of diarrhea and occasionally hospitalization. Improved surveillance and application of sensitive molecular diagnostics have further defined the impact of HAstV infections in children. These studies have shown that HAstV infections are clinically milder (diarrhea, vomiting, fever) than infections with other enteric agents. Among the 8 serotypes of HAstV identified, serotype 1 is the predominant strain worldwide. In addition to serotype 1, the detection rate of HAstV types 2 to 8 has increased by using newly developed assays. HAstV is less common compared with other major gastroenteritis viruses, including norovirus and rotavirus; however, it is a potentially important viral etiological agent with a significant role in acute gastroenteritis. A better understanding of the molecular epidemiology and characteristics of HAstV strains may be valuable to develop specific prevention strategies.

Post-discharge follow-up of hospital-associated infections in paediatric patients with conventional questionnaires and electronic surveillance

BACKGROUND

Viral infections are common causes of hospital-associated infections (HAIs) in paediatric patients, with most of these infections only becoming evident after discharge.

AIM

To analyse the benefits and costs of conventional and electronic surveillance methods for conducting HAI follow-ups.

METHODS

A comparison was made between response rate, time required per patient and costs to the healthcare system of conventional and electronic surveillance methods (sms, e-mail, telephone call).

FINDINGS

Altogether 1927 patients participated in the conventional followed up in 2001-2003, of whom 1175 (61%) returned the questionnaire; during the electronic surveillance period in 2005-2007, 2309 patients were followed-up in hospital, and 1940 of them (84%) returned the post-discharge information to us. The time needed by HCWs was 33 min per patient in the conventional follow-up and 13 min in the electronic follow-up, the total costs per patient being €15.07 and €13.61 respectively. A decrease of 17.1% in annual expenses was achieved with the electronic follow-up. The incidence of HAI was 8.4% in the conventional period and 12.2% in the electronic surveillance period, most cases becoming symptomatic after hospitalization.

CONCLUSION

Electronic data collection was a convenient way of implementing a continuous HAI follow-up, achieving both a higher participation rate and lower costs.

Molecular epidemiology of enteric viruses in children with sporadic gastroenteritis in Valencia, Venezuela

The epidemiology and clinical symptoms in infants and young children with acute sporadic viral gastroenteritis due to viral etiologies other than rotaviruses have not been studied thoroughly in developing countries. Fecal specimens from 480 children <5 years of age who were admitted to a large children's hospital in the city of Valencia, Venezuela, with acute diarrhea during January to December 2003 were collected and screened by ELISA and RT-PCR for rotavirus, adenovirus, norovirus, sapovirus, and astrovirus. Viral isolates were partially characterized by phylogenetic analysis. Norovirus viral load was determined by qRT-PCR. Viruses were identified in 205 (43%) of the 480 stool samples collected. Rotavirus was the virus detected most frequently (21%), followed by norovirus (13%), adenovirus (5%), sapovirus (3%), and astrovirus (2%). Viral infection rates were highest in the 6- to 11-month-old group (49%) and lowest in children >24 months old. Norovirus GII was more prevalent (90%) than GI (10%). Enteric adenovirus (serotypes 40/41) was present in 43% of the adenovirus-positive samples. Rotavirus infection caused more severe clinical symptoms than the other viruses detected, with more vomiting (84%) and dehydration (11%) that led to hospital admission of 20% of the children with acute gastroenteritis. Rotavirus and norovirus showed marked and opposite seasonal patterns. No association was observed between disease severity and viral load in children infected with norovirus. These results not only confirm the impact of rotavirus infection in Venezuela but also indicate that other enteric viruses, especially noroviruses, contribute significantly to sporadic acute gastroenteritis and to the burden of disease.

Frequent detection of human adenovirus from the lower gastrointestinal tract in men who have sex with men

Background

The association between baseline seropositivity to human adenovirus (HAdV) type 5 and increased HIV acquisition in the Step HIV Vaccine Study has raised questions concerning frequency of acquired and/or persistent Adenovirus infections among adults at high risk of HIV-1 infection.

Methodology

To evaluate the frequency and pattern of HAdV shedding from the lower GI tract, we retrospectively tested rectal swabs for HAdVs in a cohort of 20 HSV-2 positive HIV-positive Peruvian men who have sex with men (MSM) undergoing rectal swabbing three times/week for 18 consecutive weeks, in a prospective study of HSV-2 suppression in HIV infection. Viral DNA was extracted and amplified using a sensitive multiplex PCR assay that detects all currently recognized HAdV types. Molecular typing of viruses was performed on selected samples by hexon gene sequencing. Baseline neutralizing antibody titers to HAdVs −5, −26, −35 and −48 were also assessed.

Principal Findings

15/20 individuals had HAdV detected during follow up. The median frequency of HAdV detection was 30% of samples (range 2.0% to 64.7%). HAdV shedding typically occurred on consecutive days in clustered episodes lasting a median of 4 days (range 1 to 9 days) separated by periods without shedding, suggesting frequent new infections or reactivation of latent infections over time. 8 of the 15 shedders had more than one type detected in follow-up. 20 HAdV types from species B, C, and D were identified, including HAdV-5, −26 and −48, HAdV types under development as potential vaccine candidates. 14/20 subjects were seropositive for HAdV-5; 15/20 for HAdV-26; 3/20 for HAdV-35; and 2/20 for HAdV-48. HAdV shedding did not correlate with CD4 count, plasma HIV-1 viral load, or titers to HAdV-5 or HAdV-35. The sole individual with HAdV-5 shedding was HAdV-5 seropositive.

Conclusions

HAdV shedding was highly prevalent and diverse, including types presently under consideration as HIV vaccine vectors. Subclinical HAdV infection of the GI tract is common among MSM in Peru; the prevalence of HAdV in the enteric tract should be evaluated in other populations. The association between ongoing recent enteric HAdV and the immune response to recombinant HAdV vaccines should be evaluated.

Detection of replicating negative-sense RNAs in CaCo-2 cells infected with human astrovirus

Human astrovirus (HAstV) is the second most important cause of viral diarrhea and acute gastroenteritis in infants under five. However, determination of the infectivity of clinical isolates is difficult, and the replication cycle of HAstV is not yet fully understood. In this study, it was attempted to detect negative-sense (-)RNAs generated during the replication of RNA viruses. We used clinical isolates of HAstV to infect CaCo-2 cells. Reverse transcription using only a sense primer followed by PCR using both sense and antisense primers showed that (-)RNAs were first detected in CaCo-2 cells between 9 and 12 h postinfection (p.i.). However, these (-)RNAs were not detected when cells were treated with the protein synthesis inhibitor cycloheximide during HAstV infection. Next, RT with only an antisense primer followed by PCR was performed to detect (+)RNA of HAstVs after production of (-)RNAs during replication. RT-PCR results using the antisense primer revealed that the amount of (+)RNA began to increase starting 9 h p.i., indicating an accumulation of the newly synthesized (+)RNA genome. Cycloheximide was observed to abrogate the increase of newly made (+)RNA during HAstV infection. In conclusion, the use of sense or antisense primers during the RT reaction together with cycloheximide enabled us to quantitatively detect (-)RNAs, and this proved to be an useful tool in understanding the replication cycle of HAstV.

Hospitalizations for nosocomial rotavirus gastroenteritis in a tertiary pediatric center: a 4-year prospective study

BACKGROUND

Although rotavirus is the most common cause of gastroenteritis worldwide, data regarding nosocomial rotavirus gastroenteritis (NRVGE) are limited. Our objectives were to study the rates, seasonality, epidemiology, and clinical features of NRVGE.

METHODS

This was a 4-year prospective study.

RESULTS

NRVGE occurred in 1% of all admissions (356/35,833), 0.8% of all hospitalization days (1164/145,595) and 0.24 cases per 100 hospitalization days. Rates of NRVGE were age-dependent, occurring in 1.8%, 1.5%, 0.3%, and 0.1% of the admissions of children age < or = 1, > 1 to 2, > 2 to 5, and > 5 years, respectively (P < .001). Of the children age > 5 years, 90% received immunosuppressive treatment or had significant underlying diseases. The number of NRVGE cases was highest in winter months, but it occurred throughout the year, and its percentage of all hospitalizations for rotavirus gastroenteritis was highest in the summer months. NRVGE occurred after a median hospitalization of 6 days, required a median hospital stay of 3 days, and warranted treatment with intravenous fluids in 67% of cases.

CONCLUSION

NRVGE is a significant health burden, especially in children age < or = 2 years, although it also can affect children age > 5 years with significant underlying disturbances. Vaccine prevention of rotavirus gastroenteritis also could reduce NRVGE and should be considered in cost-effectiveness analyses.

The burden of rotavirus gastroenteritis in children presenting to a paediatric hospital

The aim of this study was to determine the burden, management and outcomes of rotavirus infection in young children presenting to a tertiary paediatric hospital in Sydney, Australia. All laboratory-confirmed cases of rotavirus in children aged <5 years were identified and medical records reviewed. In 2004, 80 children aged <5 years presented to the hospital with rotavirus gastroenteritis confirmed by stool testing. Infants aged <24 months comprised 75% of cases, with more males than females affected. Most children (86%) acquired rotavirus infection in the community, with a mean length of hospital admission of 2·3 days. There were eight cases of nosocomial infection at a rate of 3/10 000 admissions. The rates of intravenous fluid management (46%) and antibiotic use (28%) were high, reflecting the severity of disease presenting in a hospital setting. These data will help inform the assessment of the recently introduced rotavirus vaccination programme in Australia.

Prevalence of human astrovirus genotypes associated with acute gastroenteritis among children in Belém, Brazil

Worldwide human astroviruses (HAstV) have increasingly been recognized as causative agents of viral gastroenteritis, mainly in infants and young children. The aim of this study was to assess the epidemiology and genotype diversity of HAstVs detected in children who participated in a trial in Belém, Brazil with the rhesus human reassortant rotavirus vaccine tetravalent (RRV-TV). From April/1990 to August/1992, 624 diarrheic stool samples were tested by enzyme immunoassay (EIA) for HAstV, with a positive rate of 4.0%. Reverse transcription-polymerase chain reaction (RT-PCR) was done in 129 samples (25 positive and 104 with twice the optical density (OD) value of negative control by EIA) being 33 positive. The overall positivity yielded by both methods was 5.4% (34/624). Genotyping of the 33 positive samples was done by type-specific RT-PCR and confirmed by sequence analysis. Phylogenetic analysis was performed using a 348-bp fragment of the ORF2 region of the capsid gene. HAstV-1 was the most prevalent, accounting for 45.5% of the isolates, followed by HAstV-2 (27.3%), HAstV-3 (12.1%), HAstV-4 (12.1%), and HAstV-6 (3.0%). The monthly distribution showed that HAstV-1 was predominant in the first year of study (May/1990 to May/1991) with highest prevalence in January/1991. HAstV-2 was predominant from July to November/1991 and HAstV-4 from September to October/1990. At 24 months of age, 30.6% of children had been infected by HAstV. The clinical symptoms registered during HAstV associated-diarrhea were usually mild. These data highlight the circulation of the different HAstV genotypes in Belém during the study period.

Diarrhea etiology in a Children's Hospital Emergency Department: a prospective cohort study

BACKGROUND

We evaluated the frequency of recovery of pathogens from children with diarrhea who presented to a pediatric emergency department and characterized the associated illnesses, to develop guidelines for performing a bacterial enteric culture.

METHODS

We conducted a prospective cohort study of all patients with diarrhea who presented to a large regional pediatric emergency department during the period from November 1998 through October 2001. A thorough microbiologic evaluation was performed on stool specimens, and the findings were correlated with case, physician, and laboratory data.

RESULTS

A total of 1626 stool specimens were studied to detect diarrheagenic bacteria and, if there was a sufficient amount of stool, Clostridium difficile toxin (688 specimens), parasites (656 specimens), and viruses (417 specimens). One hundred seventy-six (47%) of 372 specimens that underwent complete testing yielded a bacterial pathogen (Shiga toxin-producing Escherichia coli, 39 specimens [of which 28 were serotype O157:H7]; Salmonella species, 39; Campylobacter species, 25; Shigella species, 14; and Yersinia enterocolitica, 2), a viral pathogen (rotavirus, 85 specimens; astrovirus, 27; adenovirus, 18; or rotavirus and astrovirus, 8), a diarrheagenic parasite (5 specimens); or C. difficile toxin (46 specimens). Samples from 2 patients yielded both bacterial and viral pathogens. A model to identify predictors of bacterial infection found that international travel, fever, and the passing of >10 stools in the prior 24 h were associated with the presence of a bacterial pathogen. Physician judgment regarding the need to perform a stool culture was almost as accurate as the model in predicting bacterial pathogens.

CONCLUSIONS

Nearly one-half of the patients who presented to the emergency department with diarrhea had a definite or plausible pathogen in their stool specimens. We were unable to develop a model that was substantially better than physician judgment in identifying patients for whom bacterial culture would yield positive results. The unexpectedly high rate of C. difficile toxin warrants further examination.

First experience with diagnosing astroviral infections in children hospitalized in Pilsen (Czechia)

Between the years 2000-2002 astroviral infection was confirmed in 0.8 % of 2606 children admitted for a diarrheal disease to the University Hospital in Pilsen (Czechia). Astrovirus infections most frequently occurred in the age group between 49-60 months, and 77.3 % of the infections occurred in winter. When the incidence was calculated for these most susceptible age groups, the positive rates were 2.4 % (between 49-60 months) and 1.2 % (between 7-12 months) respectively. On average the hospitalization lasted for 5 d, the diarrhea 3.7 d, vomiting 1.1 d, and 40.9 % of infected children had a raised temperature. In 7 out of 872 stool samples (0.8 %), astrovirus antigen has appeared in the course of the monitored period, i.e. nosocomial astrovirus infection was recorded. In view of the rarity of detecting astroviral infections it is probably not effective to include the diagnosis of these infections in the routine panel when examining the children admitted for gastrointestinal infections. The diagnosis of these infections should, however, be performed within the framework of epidemic incidence and in nosocomial infections.

Rotavirus vaccines and the prevention of hospital-acquired diarrhea in children

Rotavirus, the major cause of severe acute dehydrating gastroenteritis in children less than 5 years of age, is responsible for an estimated 20-50% of all hospitalizations for diarrhea and approximately 440,000 deaths annually, primarily in the developing world. Rotavirus vaccines are considered the most promising means for disease prevention. While the prime rationale for developing rotavirus vaccines has been the enormous burden of rotavirus infection leading to severe and fatal disease, a secondary benefit may be the prevention of nosocomial rotavirus diarrhea. We have reviewed the burden of intra-hospital-acquired rotavirus infections from several countries and found that in the United States alone, as many as 25% of rotavirus hospitalizations or approximately 16,000-18,000 hospitalizations each year might be due to rotavirus infections acquired within hospitals. To countries with low rotavirus-associated mortality, prevention of these infections and the resulting economic savings therefore represent an important secondary goal. Several rotavirus vaccines are in development, and two candidates are currently being tested in large-scale safety and efficacy trials. Development of safe and effective rotavirus vaccines will protect children worldwide against the severe consequences of rotavirus infections including prolonged hospitalizations for nosocomially acquired infections.

PCR detection of pathogenic viruses in southern California urban rivers

AIMS

To investigate human viral contamination in urban rivers and its impact on coastal waters of southern California, USA.

METHODS AND RESULTS

Three types of human viruses (adeno, entero and hepatitis A) were detected using nested- and RT-PCR from 11 rivers and creeks. Faecal indicator bacteria as well as somatic and F-specific coliphage were also tested. Approximately 50% of the sites were positive for human adenoviruses. However, there was no clear relationship between detection of human viruses and the concentration of indicator bacteria and coliphage. Both faecal indicator bacteria and human viral input at beaches near river mouths were associated with storm events. The first storm of the wet season seemed to have the greatest impact on the quality of coastal water than following storm events.

CONCLUSIONS

This study provides the first direct evidence that human viruses are prevalent in southern California urban rivers. Urban run-off impacts coastal water quality most significantly during the storm season.

SIGNIFICANCE AND IMPACT OF THE STUDY

To protect human health during water recreational activities, it is necessary to develop effective strategies to manage urban run-off during storm events.

Gastroenteritis aguda nosocomial e infección asintomática por rotavirus y astrovirus en niños hospitalizados

BACKGROUND

Nosocomial gastroenteritis is frequent in pediatric hospital wards. Between 20% and 50% of gastroenteritis cases caused by rotavirus and astrovirus are of nosocomial origin.

OBJECTIVE

To determine the incidence of nosocomial rotavirus and astrovirus gastroenteritis in our environment, the incidence of asymptomatic infection with these viruses, and to identify the G serotypes of the rotaviruses detected.

METHODS

We performed a prospective study of all children under 2 years of age admitted to a neonatology unit over a 1-year period who were followed-up for the presence of diarrhea and periodic study of feces to detect the presence of rotavirus and astrovirus antigens by enzyme immunoassay (EIA). Patients with gastroenteritis also underwent bacteria stool culture, adenovirus detection by EIA, calcivirus detection by polymerase chain reaction, and analysis of rotavirus G serotypes by EIA with monoclonal antibodies.

RESULTS

Of 666 children admitted without diarrhea, 60 presented nosocomial gastroenteritis (9 % of patients admitted and 1.75 per 100 days of hospital stay): 34 presented rotavirus (5 % of patients) and two presented astrovirus (0.3 % of patients). Of the 329 patients without diarrhea who were studied, viral elimination was detected in 27: rotavirus in 23 patients and astrovirus in four. Viral infection was detected on admission in 13 patients (4 %) and after 72 hours in 14 patients (4.2 %) (asymptomatic nosocomial infection). No differences in the distribution of rotavirus G serotypes were observed between community-acquired and nosocomial gastroenteritis.

CONCLUSIONS

These data confirm the importance of viral etiology in nosocomial gastroenteritis and allow us to evaluate asymptomatic fecal elimination of rotavirus as one of the factors in the transmission of this infection.

Protein products of the open reading frames encoding nonstructural proteins of human astrovirus serotype 8

Human astroviruses have a positive-strand RNA genome, which contains three open reading frames (ORF1a, ORF1b, and ORF2). The genomic RNA is translated into two nonstructural polyproteins, nsp1a and nsp1ab, that contain sequences derived from ORF1a and from both ORF1a and ORF1b, respectively. Proteins nsp1a and nsp1ab are thought to be proteolytically processed to yield the viral proteins implicated in the replication of the virus genome; however, the intermediate and final products of this processing have been poorly characterized. To identify the cleavage products of the nonstructural polyproteins of a human astrovirus serotype 8 strain, antisera to selected recombinant proteins were produced and were used to analyze the viral proteins synthesized in astrovirus-infected Caco-2 cells and in cells transfected with recombinant plasmids expressing the ORF1a and ORF1b polyproteins. Pulse-chase experiments identified proteins of approximately 145, 88, 85, and 75 kDa as cleavage intermediates during the polyprotein processing. In addition, these experiments and kinetic analysis of the synthesis of the viral proteins identified polypeptides of 57, 20, and 19 kDa, as well as two products of around 27 kDa, as final cleavage products, with the 57-kDa polypeptide most probably being the virus RNA polymerase and the two approximately 27-kDa products being the viral protease. Based on the differential reactivities of the astrovirus proteins with the various antisera used, the individual polypeptides detected were mapped to the virus ORF1a and ORF1b regions.

Astrovirus infection in children

PURPOSE OF REVIEW

Public health concerns related to enteric viral agents, such as astroviruses and caliciviruses, include their ability to cause sporadic diarrhea, large outbreaks of gastroenteritis, and hospitalizations or deaths resulting from vomiting, diarrhea, and dehydration. Improved surveillance and application of sensitive molecular assays has increased awareness of these enteric pathogens and reduced the 'diagnostic gap' or unknown causes of non-bacterial gastroenteritis.

RECENT FINDINGS

Molecular assays have been applied to further describe the epidemiology of human astroviruses from a variety of geographic areas. The burden of astrovirus infections compared with other enteric viral agents, including rotaviruses, caliciviruses, and enteric adenoviruses have been reported. New methods for detection of astroviruses such as reverse transcription-polymerase chain reaction and molecular typing methods have advanced the understanding of the epidemiology. Additional molecular studies have described the protein processing mechanisms of this single-stranded RNA virus.

SUMMARY

Astroviruses are increasingly recognized as significant gastrointestinal pathogens. The understanding of molecular epidemiology and molecular processing of the virus may lead to specific prevention strategies.