Improved detection of rotavirus shedding by polymerase chain reaction

Impact of rotavirus vaccination in Malawi from 2012 to 2022 compared to model predictions before, during, and after the COVID-19 pandemic

Background

Rotarix® rotavirus vaccine was introduced into the Malawi national immunization program in October 2012. We used a previously developed mathematical models to estimate overall vaccine effectiveness over a 10-year period following rotavirus vaccine introduction.

Methods

We analyzed data on children <5 years old hospitalized with acute gastroenteritis in Blantyre, Malawi from January 2012 to June 2022, compared to pre-vaccination data. We estimated vaccine coverage before, during, and after the COVID-19 pandemic using data from rotavirus-negative children. We compared model predictions for the weekly number of rotavirus-associated gastroenteritis (RVGE) cases to the observed number by age to validate model predictions and estimate overall vaccine effectiveness.

Results

The number of RVGE and rotavirus-negative acute gastroenteritis cases declined substantially following vaccine introduction. Vaccine coverage among rotavirus-negative controls was >90% with two doses by July 2014, and declined to a low of ~80% in October 2020, before returning to pre-pandemic levels by July 2021. Our models captured the post-vaccination trends in RVGE incidence, with 5.4% to 19.4% of observed weekly RVGE cases falling outside of the 95% prediction intervals. Comparing observed RVGE cases to the model-predicted incidence without vaccination, overall vaccine effectiveness was estimated to be 36.0% (95% prediction interval: 33.6%, 39.9%) peaking in 2014 and was highest in infants (52.5%; 95% prediction interval: 50.1%, 54.9%).

Conclusions

Overall effectiveness of rotavirus vaccination in Malawi is modest despite high vaccine coverage and has plateaued since 2016. Our mathematical models provide a validated platform for assessing strategies to improve rotavirus vaccine impact.

Seasonal pattern in occurrence of rotavirus infection (RV) in diarrheic children, calves and piglets from Bareilly, India

Rapid and reliable diagnosis for diarrhoeal disease is critically important for the differentiation of etiological agents and subsequent suitable treatment modalities. The objective of the study is to reveal the seasonal pattern in the occurrence of rotavirus in diarrheic children, calves and piglets from Bareilly, Uttar Pradesh, India. A total of 115 diarrhoeal samples were collected, out of which 51 were collected during post-monsoon/autumn (September 2018-November 2018) and 64 during the winter season (December 2018-February 2019). The samples were collected from children <5 years (n = 50), piglets <3 months (n = 35) and calves <6 months of age (n = 30). These samples were screened by ribonucleic acid-polyacrylamide gel electrophoresis (RNA-PAGE) and reverse transcriptase-polymerase chain reaction (RT-PCR) by targeting the VP6 gene of rotavirus A (RVA) and the two were compared. In RNA-PAGE 29.4% (5/17), 6.3% (1/16) and 0% (0/18) samples collected from children, calves and piglets, respectively were rotavirus positive during the autumn season while 45.5% (15/33), 21.4% (3/14) and 17.7% (3/17) samples in the winter season. In RT-PCR, 41.2% (7/17), 12.5% (2/16) and 0% (0/18) samples were rotavirus positive in the autumn season while 51.5% (17/33), 28.6% (4/14) and 29.4% (5/17) samples in winter season collected from children, calves and piglets, respectively. On statistical analysis, no significant difference between the season and number of positives in children and calves (p > 0.05) was observed, however in piglets significantly higher number of RVA positives were detected in the winter season than autumn (p < 0.01). The diagnostic test comparison of RNA-PAGE and RT-PCR showed no statistically significant difference in detecting the RVA positives (p > 0.05). Overall the percent positivity showed a seasonal pattern with higher positivity in winter as compared to autumn season.

Model-based estimation of the impact on rotavirus disease of RV3-BB vaccine administered in a neonatal or infant schedule

Rotavirus infection is a common cause of severe diarrheal disease and a major cause of deaths and hospitalizations among young children. Incidence of rotavirus has declined globally with increasing vaccine coverage. However, it remains a significant cause of morbidity and mortality in low-income countries where vaccine access is limited and efficacy is lower. The oral human neonatal vaccine RV3-BB can be safely administered earlier than other vaccines, and recent trials in Indonesia have demonstrated high efficacy. In this study, we use a stochastic individual-based model of rotavirus transmission and disease to estimate the anticipated population-level impact of RV3-BB following delivery according to either an infant (2, 4, 6 months) and neonatal (0, 2, 4 months) schedule. Using our model, which incorporated an age- and household-structured population and estimates of vaccine efficacy derived from trial data, we found both delivery schedules to be effective at reducing infection and disease. We estimated 95-96% reductions in infection and disease in children under 12 months of age when vaccine coverage is 85%. We also estimate high levels of indirect protection from vaccination, including 78% reductions in infection in adults over 17 years of age. Even for lower vaccine coverage of 55%, we estimate reductions of 84% in infection and disease in children under 12 months of age. While open questions remain about the drivers of observed lower efficacy in low-income settings, our model suggests RV3-BB could be effective at reducing infection and preventing disease in young infants at the population level.

Evaluating strategies to improve rotavirus vaccine impact during the second year of life in Malawi

Rotavirus vaccination has substantially reduced the incidence of rotavirus-associated gastroenteritis (RVGE) in high-income countries, but vaccine impact and estimated effectiveness are lower in low-income countries for reasons that are poorly understood. We used mathematical modeling to quantify rotavirus vaccine impact and investigate reduced vaccine effectiveness, particularly during the second year of life, in Malawi, where vaccination was introduced in October 2012 with doses at 6 and 10 weeks. We fitted models to 12 years of prevaccination data and validated the models against postvaccination data to evaluate the magnitude and duration of vaccine protection. The observed rollout of vaccination in Malawi was predicted to lead to a 26 to 77% decrease in the overall incidence of moderate-to-severe RVGE in 2016, depending on assumptions about waning of vaccine-induced immunity and heterogeneity in vaccine response. Vaccine effectiveness estimates were predicted to be higher among 4- to 11-month-olds than 12- to 23-month-olds, even when vaccine-induced immunity did not wane, due to differences in the rate at which vaccinated and unvaccinated individuals acquire immunity from natural infection. We found that vaccine effectiveness during the first and second years of life could potentially be improved by increasing the proportion of infants who respond to vaccination or by lowering the rotavirus transmission rate. An additional dose of rotavirus vaccine at 9 months of age was predicted to lead to higher estimated vaccine effectiveness but to only modest (5 to 16%) reductions in RVGE incidence over the first 3 years after introduction, regardless of assumptions about waning of vaccine-induced immunity.

Modeling of rotavirus transmission dynamics and impact of vaccination in Ghana

Background:

Rotavirus incidence remains relatively high in low-income countries (LICs) compared to high-income countries (HICs) after vaccine introduction. Ghana introduced monovalent rotavirus vaccine in April 2012 and despite the high coverage, vaccine performance has been modest compared to developed countries. The predictors of low vaccine effectiveness in LICs are poorly understood, and the drivers of subnational heterogeneity in rotavirus vaccine impact are unknown.

Methods:

We used mathematical models to investigate variations in rotavirus incidence in children <5 years old in Ghana. We fit models to surveillance and case-control data from three different hospitals: Korle-Bu Teaching Hospital in Accra, Komfo Anokye Teaching Hospital in Kumasi, and War Memorial Hospital in Navrongo. The models were fitted to both pre- and post-vaccine data to estimate parameters describing the transmission rate, waning of maternal immunity, and vaccine response rate.

Results:

The seasonal pattern and age distribution of rotavirus cases varied among the three study sites in Ghana. Our model was able to capture the spatio-temporal variations in rotavirus incidence across the three sites and showed good agreement with the age distribution of observed cases. The rotavirus transmission rate was highest in Accra and lowest in Navrongo, while the estimated duration of maternal immunity was longer (∼5 months) in Accra and Kumasi and shorter (∼3 months) in Navrongo. The proportion of infants who responded to the vaccine was estimated to be high in Accra and Kumasi and low in Navrongo.

Conclusions:

Rotavirus vaccine impact varies within Ghana. A low vaccine response rate was estimated for Navrongo, where rotavirus is highly seasonal and incidence limited to a few months of the year. Our findings highlight the need to further explore the relationship between rotavirus seasonality, maternal immunity, and vaccine response rate to determine how they influence vaccine effectiveness and to develop strategies to improve vaccine impact.

Surveillance data confirm multiyear predictions of rotavirus dynamics in New York City

Prediction skill is a key test of models for epidemic dynamics. However, future validation of models against out-of-sample data is rare, partly because of a lack of timely surveillance data. We address this gap by analyzing the response of rotavirus dynamics to infant vaccination. Syndromic surveillance of emergency department visits for diarrhea in New York City reveals a marked decline in diarrheal incidence among infants and young children, in line with data on rotavirus-coded hospitalizations and laboratory-confirmed cases, and a shift from annual to biennial epidemics increasingly affecting older children and adults. A published mechanistic model qualitatively predicted these patterns more than 2 years in advance. Future efforts to increase vaccination coverage may disrupt these patterns and lead to further declines in the incidence of rotavirus-attributable gastroenteritis.

Clinical and Imaging Findings of Neonatal Seizures Presenting as Diffuse Cerebral White Matter Abnormality on Diffusion-Weighted Imaging without any Structural or Metabolic Etiology

Purpose

Some patients with neonatal seizures show diffuse, symmetric diffusion-restricted lesions in the cerebral white matter. The aim of this study was to describe clinical and imaging findings of patients with neonatal seizures who had diffuse, symmetric diffusion-restricted lesions without any structural or metabolic etiology.

Materials and Methods

A total of 56 neonates aged less than 1 week underwent brain magnetic resonance imaging (MRI) for evaluation of seizures from November 2008 to February 2017. After excluding 43 patients, 13 patients showed diffuse white matter abnormality on diffusion-weighted imaging. Initial and follow-up clinical and MRI findings were analyzed retrospectively.

Results

All 13 patients were born at full term. Among the ten patients who underwent a stool test for viruses, six were positive for rotavirus and one for astrovirus. MRI revealed diffuse, symmetric diffusion-restricted lesions distributed along the cerebral white matter, thalami, and midbrain variably.

Conclusion

Diffuse, symmetric diffusion-restricted lesions involving the cerebral white matter can be seen in patients with neonatal seizures without any structural or metabolic etiology. Rotavirus is commonly but not exclusively detected in these patients. Nevertheless, viral infection-associated encephalopathy should be considered for patients with characteristic clinical and MRI findings.

Highly sensitive ELISA for the serological detection of murine rotavirus EDIM based on its major immunogen VP6

Precise health monitoring of laboratory animals is a critical factor for surveillance and accuracy of animal experiments. Rotavirus epizootic diarrhea of infant mice (EDIM) leads to infections in mice that can influence animal studies, e.g., by altering the intestinal physiology. Thus, the aim of this study was establishing a highly sensitive and specific ELISA for the serological detection of EDIM infections in rodents. First, virus proteins were separated by SDS-PAGE and immunogenic proteins were visualized by immunoblotting and identified after in-gel digestion by tandem mass spectrometry. Subsequently, the major immunogen VP6 (virus protein 6) was expressed in Escherichia coli in high yields, purified by affinity chromatography, and used to establish an indirect ELISA. The diagnostic sensitivity and specificity were both above 99 % and the selectivity better than 98.7 % for animals infected by other pathogens listed by the Federation of Laboratory Animal Science Associations. Importantly, the Strep-rVP6-His-ELISA was more sensitive than a commercial virus-based ELISA and is a time- and cost-efficient complement to EDIM-specific immune-fluorescence assays. In conclusion, the assay can improve health monitoring by reducing the risk of missed EDIM infections in animal housing facilities, thereby improving animal welfare, reliability of animal studies, and protection of precious mice breeds.

Cynomolgus Monkeys (Macaca fascicularis) as an Experimental Infection Model for Human Group A Rotavirus

Group A rotaviruses (RVA) are one of the most common causes of severe acute gastroenteritis in infants worldwide. Rotaviruses spread from person to person, mainly by faecal–oral transmission. Almost all unvaccinated children may become infected with RVA in the first two years of life. The establishment of an experimental monkey model with RVA is important to evaluate new therapeutic approaches. In this study, we demonstrated viral shedding and viraemia in juvenile–adult Macaca fascicularis orally inoculated with Wa RVA prototype. Nine monkeys were inoculated orally: seven animals with human RVA and two control animals with saline solution. During the study, the monkeys were clinically monitored, and faeces and blood samples were tested for RVA infection. In general, the inoculated animals developed an oligosymptomatic infection pattern. The main clinical symptoms observed were diarrhoea in two monkeys for three days, associated with a reduction in plasmatic potassium content. Viral RNA was detected in seven faecal and five sera samples from inoculated animals, suggesting virus replication. Cynomolgus monkeys are susceptible hosts for human Wa RVA infection. When inoculated orally, they presented self-limited diarrhoea associated with presence of RVA infectious particles in faeces. Thus, cynomolgus monkeys may be useful as animal models to evaluate the efficacy of new antiviral approaches.

Evolution in fecal bacterial/viral composition in infants of two central African countries (Gabon and Republic of the Congo) during their first month of life

Few studies have analyzed the gut microbiota of child in unindustrialized countries, but none during the first month of life. Stool samples were collected from healthy newborns in hospitals of Gabon (n = 6) and Republic of the Congo (n = 9) at different time points during the first month of life: meconium, day 2 (D02), day 7 (D07) and day 28 (D28). In addition, one fecal sample was collected from each mother after delivery. Metagenomic sequencing was performed to determine the bacterial communities, and multiplex real-time PCR was used to detect the presence of seven enteric viruses (rotavirus a, adenovirus, norovirus I and II, sapovirus, astrovirus, enterovirus) in these samples. Bacterial diversity was high in the first days of life, and was dominated by the genus Prevotella. Then, it rapidly decreased and remained low up to D28 when the gut flora was composed almost exclusively of strictly anaerobic bacteria. Each infant’s fecal bacterial microbiota composition was significantly closer to that of their mother than to that of any other woman in the mothers’ group, suggesting an intrauterine, placental or amniotic fluid origin of such bacteria. Moreover, bacterial communities differed according to the delivery mode. Overall, the bacterial microbiota communities displayed a similar diversification and expansion in newborns within and between countries during the first four weeks of life. Moreover, six of the fifteen infants of this study harbored enteric viruses (rotavirus, enterovirus and adenovirus) in fecal samples, but never in the meconium. A maternal source for the viruses detected at D02 and D07 can be excluded because none of them was found also in the child’s mother. These findings improve our knowledge on the gut bacterial and viral communities of infants from two Sub-Saharan countries during their first month of life.

The molecular epidemiology of bovine rotaviruses circulating in Iran: a two-year study

Bovine group A rotavirus (bovine RVA) is recognized as a major cause of severe gastroenteritis in newborn calves. The purpose of this study was to estimate the prevalence and identify the genotypes of circulating bovine RVA in newborn diarrheic calves. Two hundred fifty-three stool samples of diarrheic calves up to 1 month old were collected from 42 industrial dairy farms in two Iranian provinces during March 2010 to February 2012. All collected samples were screened for the presence of bovine RVA by RT-PCR, and the G and P genotypes were determined by semi-nested multiplex RT-PCR assay. The results of RT-PCR indicated that 49.4 % (125 out of 253) of the samples were positive for bovine RVA. The G and P genotyping of a subset of positive samples (n = 85) by semi-nested multiplex RT-PCR revealed that G6 (55.3 %) and G10 (43.5 %) and P[5] (51.8 %) and P[11] (27 %) were the most prevalent G and P genotypes, respectively. G6P[5] was the dominant genotype (35.3 %), followed by G10P[5], G10P[11] and G6P[11], with prevalence rates of 16.5 %, 15.3 % and 10.6 %, respectively. Sequence analysis of 20 VP7 and four VP4 genes showed highest nucleotide sequence identity with the corresponding genes of strains RVA/Cow-tc/GBR/UK/1973/G6P7[5] and RVA/Cow-tc/USA/B223/XXXX/G10P[11]. The results of this study reveal the diversity of G and P genotypes in bovine RVA samples from diarrheic Iranian calves and expands our knowledge of bovine RVA infections in the Middle East. These results also highlight the importance of producing of an effective rotavirus vaccine and its inclusion in the national cattle immunization program.

Did Large-Scale Vaccination Drive Changes in the Circulating Rotavirus Population in Belgium?

Vaccination can place selective pressures on viral populations, leading to changes in the distribution of strains as viruses evolve to escape immunity from the vaccine. Vaccine-driven strain replacement is a major concern after nationwide rotavirus vaccine introductions. However, the distribution of the predominant rotavirus genotypes varies from year to year in the absence of vaccination, making it difficult to determine what changes can be attributed to the vaccines. To gain insight in the underlying dynamics driving changes in the rotavirus population, we fitted a hierarchy of mathematical models to national and local genotype-specific hospitalization data from Belgium, where large-scale vaccination was introduced in 2006. We estimated that natural- and vaccine-derived immunity was strongest against completely homotypic strains and weakest against fully heterotypic strains, with an intermediate immunity amongst partially heterotypic strains. The predominance of G2P[4] infections in Belgium after vaccine introduction can be explained by a combination of natural genotype fluctuations and weaker natural and vaccine-induced immunity against infection with strains heterotypic to the vaccine, in the absence of significant variation in strain-specific vaccine effectiveness against disease. However, the incidence of rotavirus gastroenteritis is predicted to remain low despite vaccine-driven changes in the distribution of genotypes.

Qualitative Effects of Monovalent Vaccination Against Rotavirus: A Comparison of North America and South America

Rotavirus is the most common cause of severe gastroenteritis in young children worldwide. The introduction of vaccination programs has led to a significant reduction in number of hospitalizations due to rotavirus in North and South American countries. Little work has been done, however, to examine the differential impact of vaccination as a function of strain distribution and strain-specific vaccine efficacy. We developed a two-strain epidemiological model of rotavirus transmission, and used it to examine the effects of a monovalent vaccine (Rotarix) on the qualitative behaviors of infection levels in a population. For contrast, we parameterized our model with strain distribution data from North America and from South America. In all cases, the introduction of the vaccine led to significant decreases in the prevalence of primary infection due to both strains for a decade or more, after which the overall prevalence recovers to near pre-vaccination levels. The prevalence of G1P[8] is significantly higher in North America (73 % of all rotavirus infections) compared to that in South America (34 %). Our model predicts that the introduction of Rotarix might result in major strain replacement in regions such as North America where the prevalence of G1P[8] is relatively high, due to higher efficacy of Rotarix against infection caused by G1P[8], while regions with lower prevalence of G1P[8], such as South America, are not susceptible to major strain replacement.

Determination of a Viral Load Threshold To Distinguish Symptomatic versus Asymptomatic Rotavirus Infection in a High-Disease-Burden African Population

We evaluated quantitative real-time PCR to establish the diagnosis of rotavirus gastroenteritis in a high-disease-burden population in Malawi using enzyme immunoassay as the gold standard diagnostic test. In 146 children with acute gastroenteritis and 65 asymptomatic children, we defined a cutoff point in the threshold cycle value (26.7) that predicts rotavirus-attributable gastroenteritis in this population. These data will inform the evaluation of direct and indirect rotavirus vaccine effects in Africa.

Viral gastroenteritis in children in Colorado 2006-2009

Acute gastroenteritis accounts for a significant burden of medically attended illness in children under the age of five. For this study, four multiplex reverse transcription PCR assays were used to determine the incidence of adenovirus, astrovirus, coronavirus, norovirus GI and GII, rotavirus, and sapovirus in stool samples submitted for viral electron microscopy (EM) to the Children's Hospital Colorado. Of 1105 stool samples available, viral RNA/DNA was detected in 247 (26.2%) of 941 pediatric samples (median age = 2.97 years, 54% male) with 28 (3.0%) positive for more than one virus. Adenovirus, astrovirus, norovirus GI, norovirus GII, rotavirus, and sapovirus were detected in 95 (10.0%), 33 (3.5%), 8 (0.9%), 90 (9.6%), 49 (5.2%), and 2 (0.2%) of the pediatric samples, respectively. No coronaviruses were identified. Sequencing of norovirus positive samples indicated an outbreak of norovirus strain GII.4 in 2006 with evidence of numerous circulating strains. Multiple samples from the same immunocompromised patients demonstrated symptomatic shedding of norovirus for up to 32 weeks and astrovirus for 12 weeks. RT‐PCR detected 99 of 111 (89%) adenovirus‐positive samples versus 12 (11%) by EM, and 186 of 192 (97%) sapovirus/astrovirus/norovirus‐positive samples versus 21 (11%) by EM. Noroviruses and adenoviruses are common causes of gastroenteritis in children. Immunocompromised patients can be infected with multiple viruses and shed viruses in their stools for prolonged periods. This data support the superiority of RT‐PCR compared to EM for diagnosis of viral gastroenteritis. J. Med. Virol. 87:931–939, 2015. © 2015 Wiley Periodicals, Inc.

Bayesian parameter inference for dynamic infectious disease modelling: rotavirus in Germany

Understanding infectious disease dynamics using epidemic models based on ordinary differential equations requires the calibration of model parameters from data. A commonly used approach in practice to simplify this task is to fix many parameters on the basis of expert or literature information. However, this not only leaves the corresponding uncertainty unexamined but often also leads to biased inference for the remaining parameters because of dependence structures inherent in any given model. In the present work, we develop a Bayesian inference framework that lessens the reliance on such external parameter quantifications by pursuing a more data-driven calibration approach. This includes a novel focus on residual autocorrelation combined with model averaging techniques in order to reduce these estimates' dependence on the underlying model structure. We applied our methods to the modelling of age-stratified weekly rotavirus incidence data in Germany from 2001 to 2008 using a complex susceptible-infectious-susceptible-type model complemented by the stochastic reporting of new cases. As a result, we found the detection rate in the eastern federal states to be more than four times higher compared with that of the western federal states (19.0% vs 4.3%), and also the infectiousness of symptomatically infected individuals was estimated to be more than 10 times higher than that of asymptomatically infected individuals (95% credibility interval: 8.1–19.6). Not only do these findings give valuable epidemiological insight into the transmission processes, we were also able to examine the considerable impact on the model-predicted transmission dynamics when fixing parameters beforehand.

Prevalence of rotavirus genotypes in South Korea in 1989-2009: implications for a nationwide rotavirus vaccine program

The epidemiology of human group A rotavirus was analyzed by examining genotypic data acquired from 1989 to 2009 in South Korea. This information was derived from all the available published articles on rotavirus studies in South Korea, retrieved from both the PubMed and KoreaMed databases. Four common G types (G1, G2, G3, and G4) and three common P types (P[8], P[4], and P[6]) accounted for approximately 93% and 99% of the rotavirus reports, respectively. The G9 type was frequently detected after 2000, and because of this prevalence, it is considered to be the fifth most important G type rotavirus after the G1.G4 genotypes. Less common G types of the virus such as G12, G11, and G10 were detected in some geographic settings, and it is important to consider the context of these subtypes and their epidemiological significance. The P[9] virus genotype was observed in the study and has been discussed in many other studies; however, the P[3], P[10] and P[25] genotypes were rarely detected in the epidemiological research. In general, the distributions of the G and P genotypes showed temporal and geographical fluctuations, and a nationwide rotavirus vaccine program that targeted these genotypes demonstrated effectiveness in protecting against the circulating rotavirus strains. However, further analysis is needed to determine the true long-term effectiveness of these vaccines; the analysis should also consider the unexpected effects of vaccinations, such as vaccine-induced diseases, herd immunity, and changes in host susceptibilities.

Comparison of Premier™ Rotaclone®, ProSpecT™, and RIDASCREEN® rotavirus enzyme immunoassay kits for detection of rotavirus antigen in stool specimens

BACKGROUND

Rotaviruses are the major cause of severe dehydrating diarrhea in children throughout the world. Enzyme immunoassays (EIAs) have been the standard method for detection of rotavirus in stool specimens since the 1980s. The World Health Organization (WHO) Rotavirus Surveillance Network has proposed including three EIA kits in the WHO-GSM (Global Management System/Système Mondial de Gestion) catalog for easy procurement of EIA kits by participating rotavirus surveillance network laboratories.

OBJECTIVES

In this study, we conducted a comparative analysis of 3 commercially available enzyme immunoassay kits: Premier™ Rotaclone® (Meridian Bioscience, Inc.), ProSpecT™ (Oxoid, Ltd.) and RIDASCREEN® (R-biopharm AG) for rotavirus diagnostics.

STUDY DESIGN

Using reverse-transcriptase-PCR (RT-PCR) as the gold standard, the 3 EIA kits were evaluated by testing a stool panel consisting of 56 rotavirus-positive and 54 rotavirus negative samples.

RESULTS

The sensitivities of the Premier™ Rotaclone®, ProSpecT™ and RIDASCREEN® kits were 76.8%, 75% and 82.1%, respectively, but did not differ significantly. The specificity of all the 3 kits was 100%. The use of RT-PCR as a gold standard lowered the observed sensitivity of all 3 EIA kits but helps to reduce equivocal results that can be seen when another EIA or other non-molecular methods are used as the reference assay in comparison studies.

CONCLUSION

Our study found that all three kits are suitable for use by rotavirus surveillance programs.

Rotavirus shedding in symptomatic and asymptomatic children using reverse transcription-quantitative PCR

Reverse transcription-real-time polymerase chain reaction (RT-qPCR) for the VP6 gene was used to study group A rotavirus shedding in children with symptomatic and asymptomatic rotavirus infection. Sequential stool samples (n = 345) from 10 children with rotavirus associated diarrhea and from five children (n = 161) with asymptomatic rotavirus infection were collected over a period of 2 months. A RT-qPCR assay on the samples using a rotavirus VP6 plasmid standard demonstrated high reproducibility, with an inter-assay coefficient of variation (CV) of 1.40-2.97% and an intra-assay CV of 0.03-3.03%. The median duration of shedding was longer in children with diarrhea compared to asymptomatic children (24 days vs. 18 days; P = 0.066). The median quantitation cycle (C(q)) at presentation in symptomatic children was 17.21 compared to 30.98 in asymptomatic children (P = 0.086). The temporal pattern in symptomatic children consisted of a high initial viral shedding coinciding with the duration of diarrhea, followed by a rapid fall, and then a small increase in secondary shedding 21 days later. Compared to children with rotavirus diarrhea, those with asymptomatic infection shed lower quantities of virus throughout the observation period. No difference was noted between the G and P genotypes of samples collected at onset of infection and during the shedding period. Shedding was intermittent in a subset of children in both groups. RT-qPCR is a useful method to characterize shedding patterns.

Enteric pathogens in stool samples of Chicago-area water recreators with new-onset gastrointestinal symptoms

BACKGROUND

Characterizing pathogens responsible for recreational waterborne gastrointestinal illness is important in estimating risk and developing management strategies to prevent infection. Although water recreation is associated with sporadic cases of gastrointestinal illness, pathogens responsible for such illness are not well characterized.

METHODS

A prospective cohort study was conducted enrolling non-water recreators (such as cyclists and joggers) and two groups of limited-contact waters recreators (such as boaters and kayakers): those on an effluent-dominated urban waterway and those on general use waters. Stool samples were collected from participants who developed gastrointestinal symptoms during a three-week follow-up period. Samples were analyzed for bacterial, viral, and protozoan pathogens. Logistic regression models were used to identify associations between water recreation and the presence of pathogens in stool samples.

RESULTS

Among 10,998 participants without gastrointestinal symptoms at baseline, 2,429 (22.1%) developed at least one symptom during 21 days of follow-up. Of those, 740 (30.5%) provided at least one stool sample, of which 76 (10.3%) were positive for a pathogen. Rotavirus, found primarily among adults, accounted for 53 of the 76 (70%) infections. Among participants with symptoms, pathogen presence was not associated with water recreation or the extent of water exposure. The range of pathogens that could be identified and sample size limitations may have contributed to this lack of association.

CONCLUSIONS

We did not find specific pathogens or groups of pathogens associated with recreational waterborne gastrointestinal illness. Although pathogens responsible for outbreaks of waterborne gastrointestinal illness have been described, microbes that cause sporadic cases remain poorly defined.

Nearly constant shedding of diverse enteric viruses by two healthy infants

Stool samples from two healthy infant siblings collected at about weekly intervals during their first year of life were analyzed by PCR for 15 different enteric viral genera. Adenovirus, Aichi virus, Anellovirus, Astrovirus, Bocavirus, Enterovirus, Parechovirus, Picobirnavirus, and Rotavirus were detected. Not detected were Coronavirus, Cardiovirus, Cosavirus, Salivirus, Sapovirus, and Norovirus. Long-term virus shedding, lasting from one to 12 months, was observed for adenoviruses, anelloviruses, bocaviruses, enteroviruses, parechoviruses, and picobirnaviruses. Repeated administration of oral poliovirus vaccine resulted in progressively shorter periods of poliovirus detection. Four nonpolio enterovirus genotypes were also detected. An average of 1.8 distinct human viruses were found per time point. Ninety-two percent (66/72) of the fecal samples tested contained one to five different human viruses. Two British siblings in the mid-1980s showed nearly constant fecal viral shedding. Our results demonstrate that frequent enteric infections with diverse viruses occur during early childhood in the absence of severe clinical symptoms.

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.

[Toward the elimination of rotavirus gastroenteritis by universal vaccination]

Rotavirus is the most important cause of severe gastroenteritis in children worldwide, and is most effectively controlled by vaccines. The Strategic Advisory Group of Experts (SAGE) of the World Health Organization (WHO) recommended, in 2009, the inclusion of rotavirus vaccination of infants into all national immunization programs. Two, live, orally-administrable vaccines are licensed globally. They are Rotarix, a G1P[8] monovalent, human rotavirus-based vaccine (GlaxoSmithKline), and RotaTeq, a pentavalent, bovine-human reassortant vaccine (Merck). Although the two vaccines are very different in antigenic composition and administration schedule, they are almost equally safe with respect to intussusception and 90-100% efficacious against severe rotavirus diarrhea. Countries where either vaccine was introduced into the national childhood immunization program have witnessed not only a drastic decrease in the number of rotavirus hospitalizations but a near 50% reduction in the number of all-cause-diarrhea hospitalizations. Rotavirus diarrhea, an emerging infectious disease because of its discovery in 1973, may now be among vaccine preventable diseases.

A critical review on a globally-licensed, live, orally-administrable, monovalent human rotavirus vaccine: Rotarix

Rotavirus is the major cause of severe gastroenteritis in children worldwide, and two, live, orally-administrable vaccines are licensed globally. They are Rotarix, a monovalent, human rotavirus-based vaccine (GlaxoSmithKline), and RotaTeq, a pentavalent, bovine-human reassortant vaccine (Merck). The RIX4414 strain, a G1P[8] virus, is contained in the Rotarix vaccine. It grows efficiently in the human intestine, as evidenced by vaccine virus shedding into faeces. Efficient multiplication of RIX4414 in the intestines may play a role in stimulating immune effectors other than neutralizing antibodies that may explain the protective immunity against fully heterotypic G2P[4] strains. The protective efficacy against severe rotavirus gastroenteritis afforded by Rotarix is consistently better against strains that share with RIX4414 both G and P serotypes (i.e., G1P[8]), or only P serotype (i.e., G3P[8], G4P[8] and G9P[8]). The Rotarix vaccine is safe regarding intussusception if its first dose is administered between 6 and 12 weeks of age and the last dose by 24 weeks of age with a minimum interval of 4 weeks between the two doses. The expansion by Advisory Committee on Immunization Practices, USA, of the age limit for the first dose to age <15 weeks, and the last dose by 8 months requires close monitoring.

Diagnosing rotavirus A associated IID: Using ELISA to identify a cut-off for real time RT-PCR

BACKGROUND

The use of RT-PCR for diagnosis of group A rotaviruses is increasing, but up to 14% of healthy individuals may be positive by RT-PCR. If RT-PCR is not well correlated with disease, rotavirus A may not always be the cause of illness in RT-PCR positive patients with infectious intestinal disease (IID).

OBJECTIVES

To describe the differences in faecal viral load between ELISA positive IID cases, RT-PCR positive cases and healthy controls. To develop a cut-off in faecal viral load for attributing illness to rotavirus A in RT-PCR positive IID cases.

STUDY DESIGN

Faecal viral load was measured, using real time RT-PCR, in 118 community IID cases and 65 healthy controls, previously tested by ELISA. Cycle threshold (Ct) values from the real-time RT-PCR were used as a proxy measure of viral load. A cut-off for attributing illness to rotavirus A was selected, using ROC analysis.

RESULTS

There was little overlap in viral load between ELISA positive IID cases (median Ct 17) and healthy controls (median Ct 37), but ELISA negative, RT-PCR positive IID cases (median Ct 37) had viral loads similar to healthy controls, indicating that RT-PCR is not detecting extra cases of group A rotavirus associated IID, only sub-clinical infections. The optimal cut-off in the real time RT-PCR was at Ct value 24-27.

CONCLUSION

ELISA is the best method for the laboratory diagnosis of rotavirus A associated IID. If RT-PCR is used, it is advisable to use a real time platform and to use a viral load cut-off equivalent to the detection limit of ELISA.

High frequency of rotavirus viremia in children with acute gastroenteritis: discordance of strains detected in stool and sera

Recently, rotavirus antigenemia and viremia have been identified in patients with acute gastroenteritis. This study examined rotavirus viremia in children hospitalized for acute gastroenteritis in order to establish its association with fecal shedding of rotavirus, infecting genotypes and antibody marker of acute infection. Thirty-one pairs of stool-serum specimens were collected from November 2004 to February 2005 together with clinical information. All paired specimens were screened for rotavirus RNA by RT-PCR using the VP6 gene primers. All stool and serum specimens were tested for rotavirus antigen and anti-rotavirus IgM respectively by ELISA. Sixteen of 31 stool-serum pairs showed the presence of rotavirus RNA. Nine stool and two serum specimens were positive only by RT-PCR. The total positivity in rotavirus RNA was significantly higher in both stools (80.6%) and sera (58.1%) than that of stool antigen (38.7%) and anti-rotavirus IgM (25.8%) (P < 0.01). All PCR positive paired specimens were typed for the VP7 (G) and VP4 (P) genes. Five of sixteen pairs could be typed for both genes. Three of the five pairs showed concordance (G2P[4]/G2P[4]) while two showed discordance (G12P[8]/G2P[4], G8P[4]/G2P[4]) in the genotypes detected in stool and serum specimens respectively. The study documents a high frequency of rotavirus viremia in patients with acute diarrhea. The discordance of rotavirus strains at the genotypic level in the serum and stool of individual patients with diarrhea suggests the susceptibility of extra-intestinal sites for rotavirus infection and the possibility of differential dissemination of rotavirus strains from the intestine.

One-step quantitative RT-PCR for the detection of rotavirus in acute gastroenteritis

The standard diagnosis of rotavirus gastroenteritis is based on the demonstration of rotavirus antigen in stools using an enzyme immunoassay (EIA). In this study, a one-step quantitative RT-PCR (Q-PCR) was used for sensitive detection of rotavirus in diarrheal stools. The primers and TaqMan probe for the Q-PCR were selected from a highly conserved region of the non-structural protein 3 (NSP3) of rotavirus. After validation, the test was applied to study rotavirus EIA positive (N=25) and EIA negative (N=143) stool specimens from cases of acute gastroenteritis of all degrees of severity in a prospective follow-up cohort of infants from 2 months to 2 years of age. Q-PCR detected all 25 EIA positive rotavirus antigens and seven additional cases that were rotavirus EIA negative, i.e. 28% more rotavirus positive cases than identified by EIA. It is concluded that Q-PCR using primers targeted at NSP3 is a rapid and sensitive method for diagnosing acute rotavirus gastroenteritis.

Enhancement of detection and quantification of rotavirus in stool using a modified real-time RT-PCR assay

A sensitive and specific real-time RT-PCR assay to detect rotavirus in stool samples was optimized and validated using a wide range of rotavirus genotypes. The target of the original TaqMan(R) assay is an 87 bp fragment of the highly conserved non-structural protein 3 (NSP3) gene. Here we modified the original assay by introducing degeneracy into the forward primer to account for sequence variation between rotavirus genotypes, added four nucleotides at the 3' end of the reverse primer to reduce its stability, and modified the probe label. Amplification and detection conditions were optimized using purified dsRNA from two cultivated strains. The limit of detection of the modified assay was calculated to be approximately 44 genome copies per reaction. To validate the reactivity of the assay, 103 archived RNAs that had been extracted from stools and genotyped during routine U.S. surveillance were tested. Samples were selected to represent both rare and common genotypes that have been detected in U.S. children. Nine genotypes known to be circulating in the United States were detected by the real-time assay demonstrating broad reactivity. In addition, other enteric viruses were not detected demonstrating that the assay is specific for rotavirus and does not cross-react with other viruses potentially present in stool samples. This real-time assay is an important addition to the arsenal of molecular tools available to quickly identify rotavirus in stool samples during routine surveillance.

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.

Rotavirus infection in adults

Rotavirus has been recognised for 30 years as the most common cause of infectious gastroenteritis in infants and young children. By contrast, the role of rotavirus as a pathogen in adults has long been underappreciated. Spread by faecal-oral transmission, rotavirus infection in adults typically manifests with nausea, malaise, headache, abdominal cramping, diarrhoea, and fever. Infection can also be symptomless. Rotavirus infection in immunocompromised adults can have a variable course from symptomless to severe and sustained infection. Common epidemiological settings for rotavirus infection among adults include endemic disease, epidemic outbreak, travel-related infection, and disease resulting from child-to-adult transmission. Limited diagnostic and therapeutic alternatives are available for adults with suspected rotavirus infection. Because symptoms are generally self-limiting, supportive care is the rule. Clinicians caring for adults with gastroenteritis should consider rotavirus in the differential diagnosis. In this review we intend to familiarise clinicians who primarily provide care for adult patients with the salient features of rotavirus pathophysiology, clinical presentation, epidemiology, treatment, and prevention.

Viral agents of acute gastroenteritis in German children: prevalence and molecular diversity

Acute gastroenteritis is a major source of morbidity and mortality among young children in developed and developing countries. Enteropathogenic viruses are regarded as particularly relevant causative agents. Between February 2001 and January 2002, fecal specimens were obtained from German children admitted to hospital with acute gastroenteritis and examined for rotaviruses, Noroviruses, enteric adenoviruses, and astroviruses using (RT-)PCR methods. Of the 59% (129/217) samples positive for > or =1 viral agent, 79% (102/129) carried rotavirus, whereas Norovirus was detected in 35% (45/129), enteric adenovirus in 14% (18/129), and astrovirus in 4% (5/129). Thirty-eight specimens contained at least two enteropathogenic viruses, with the majority of coinfections attributable to rotavirus/Norovirus dual infections. Sequence analysis revealed a cocirculation of G1, G3, G4, and G9 type rotavirus with G1 being the most common and G9 the second most common rotavirus G-type. Emergence of G9 rotaviruses in Germany may have implications for future vaccine development. A variety of Norovirus genotypes, most belonging to GGII, were found. Apart from subgenus F, adenovirus related genetically to subgenera A-C were detected. All astroviruses belonged to genotype 1. This is the first study concerning German children admitted to hospital that assesses the relative importance of these viruses by nested (RT-) PCR methods.

Molecular and immunological methods to detect rotavirus in formalin-fixed tissue

In 1999, a tetravalent rhesus-based rotavirus vaccine was withdrawn from the market after reports of intussusception cases among vaccinated infants. Methods to detect rotavirus in formalin-fixed pathology specimens from such patients will be important in examining the possible associations between the vaccine and intussusception, in investigating fatalities caused by natural rotavirus infection, and in furthering our understanding of the pathogenesis of rotavirus disease. Three different methods, reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemistry (IHC), and in situ hybridization (ISH), were developed to detect rotavirus in infected cell lines that were fixed in formalin and embedded in paraffin. Using specific primer pairs to identify the VP4 gene with a one-step RT-PCR method, we detected simian rotavirus strains RRV and YK-1 in the liver of an RRV-infected SCID mouse and in the small intestine of an YK-1 infected macaque, respectively. Using a two-step indirect immunoalkaline phosphatase technique, we found RRV antigens in the liver of an infected SCID mouse with a rabbit polyclonal anti-group A rotavirus antibody and a murine monoclonal anti-rotavirus VP2 antibody. Using riboprobes designed to detect RRV genes, VP4 and NSP4, we obtained a positive hybridization signal in the same area of the infected SCID mouse liver as the area in which rotavirus antigens were localized. These techniques should prove valuable to detect rotavirus antigens and nucleic acids in tissues from patients infected naturally with rotavirus or with intussususception associated with rotavirus vaccine.

Prolonged shedding of rotavirus in a geriatric inpatient

This study concerns a nosocomial rotaviral infection of a geriatric patient with clinical symptoms of acute gastroenteritis. The virological diagnosis was based on the detection of rotaviral antigens using a Rota kit, viral genome RNA by reverse transcription-polymerase chain reaction method, and viral particles by electron microscopy in the stool samples. Prolonged rotaviral shedding was suggested to be due to impaired natural killer cell activity, possibly together with deficiency of specific local immune response of the patient.

Effect of rotavirus vaccine on Sapporo virus gastroenteritis in Finnish infants

BACKGROUND

Sapporo-like viruses (SLVs) occur worldwide, but there is limited information about the SLV-associated gastroenteritis outside Japan.

METHODS

Stool specimens from 1,432 episodes of gastroenteritis that occurred in children between 2 months and 2 years of age during a rotavirus vaccine trial (776 episodes in placebo-vaccinated and 656 in rotavirus-vaccinated infants) were examined for SLVs using a reverse transcription-PCR assay. The reverse transcription-PCR took advantage of new primers specific for Sapporo virus genetic clusters I, II and III; SV/SV82 (SV/Sapporo virus 82); SV/Lond92 (SV/ London 92); and SV/PV (Parkville virus).

RESULTS

SLVs were detected in association with 132 (9.2%) of all episodes; in 80 (5.6%) episodes SLV was the only gastroenteritis virus detected. The epidemic season of SLVs peaked from March to May concurrently with rotaviruses and astroviruses and overlapping withNorwalk-like viruses. Clinically SLV gastroenteritis was characterized by a mild diarrheal disease, being sharply different from the Norwalk-like virus-associated "winter vomiting disease." Rotavirus vaccination did not have any effect on the number of SLV episodes, but the intensity and duration of SLV-associated diarrhea were reduced in rotavirus-vaccinated children compared with placebo-vaccinated children (P = 0.0008).

CONCLUSIONS

SLVs are common causative agents of acute gastroenteritis in young Finnish children. SLV disease is characterized by diarrhea, which is usually mild but can be severe. By an unknown mechanism rotavirus vaccine seems to reduce the severity of SLV-associated diarrhea.

Human caliciviruses in acute gastroenteritis of young children in the community

Episodes of acute gastroenteritis in prospectively followed children between 2 months and 2 years of age were examined for rotaviruses, enteric adenoviruses, astroviruses, and human caliciviruses, including both Norwalk-like viruses (NLVs) and Sapporo-like viruses (SLVs), using PCR and reverse transcription (RT)-PCR assays. A virus was identified in 60% (502/832) of all episodes and in 85% of the moderately severe or severe episodes. Human caliciviruses were as common as rotaviruses, both being detected in 29% of the cases. NLVs accounted for a 20% etiologic share of all cases; the clinical picture was a moderately severe disease with vomiting as a predominant symptom. SLVs were detected in 9% of the cases, the clinical picture being a mild diarrheal disease. Astroviruses were found in 10% and enteric adenoviruses in 6% of the cases. Diagnosis with PCR and RT-PCR methods increases the detection of all gastroenteritis viruses, particularly human caliciviruses. As a group, human caliciviruses are common causative agents of gastroenteritis in children <2 years of age in Finland, and, of these, NLVs cause more severe disease than SLVs.

Rotaviruses detected by reverse transcription polymerase chain reaction in acute gastroenteritis during a trial of rhesus-human reassortant rotavirus tetravalent vaccine: implications for vaccine efficacy analysis

BACKGROUND

Rotaviruses are routinely diagnosed by detection of rotavirus antigen in stools using an enzyme immunoassay (EIA). A sensitive method, like reverse transcription polymerase chain reaction (RT-PCR), may reveal more rotaviruses, but the clinical significance of such findings is not well established.

OBJECTIVES

To study whether RT-PCR can detect more episodes of rotavirus-associated gastroenteritis than EIA and to determine how rotavirus RT-PCR findings might change efficacy analysis of a rotavirus vaccine trial, in which the outcome measure was rotavirus gastroenteritis diagnosis with EIA.

STUDY DESIGN

We applied RT-PCR for detection of rotaviruses in gastroenteritis episodes encountered in an efficacy trial of rhesus-human reassortant rotavirus tetravalent (RRV-TV) vaccine, in a total of 2398 infants. During a follow-up, covering two rotavirus epidemic seasons, 256 cases of rotavirus associated gastroenteritis were detected by EIA; 226 were in the primary efficacy analysis period that included children who had received three doses of vaccine or placebo.

RESULTS

With RT-PCR, 84 (33%) more cases of rotavirus gastroenteritis were diagnosed than with EIA, 65 of these were in the primary efficacy analysis period. Clinically, cases of rotavirus gastroenteritis diagnosed by RT-PCR were much milder (median severity score 6 on a 20-point scale) than those diagnosed by EIA (median score 11), P < 0.0001. RT-PCR revealed proportionally more G2 and G4 rotaviruses than EIA. G1 rotaviruses detected by RT-PCR were almost equally divided between RRV-TV (25) vaccine and placebo (28) groups, whereas an apparent vaccine protective effect was seen in the distribution of G2 (one in the RRV-TV and eight in the placebo group) and G4 rotaviruses (six in the RRV-TV and 14 in the placebo group).

CONCLUSION

RT-PCR is a useful tool in the diagnosis of rotavirus gastroenteritis, particularly for cases associated with other than the epidemiologically dominant G-type. Application of RT-PCR contributes to the overall appraisal of performance of rotavirus vaccine.

Extended excretion of rotavirus after severe diarrhoea in young children

BACKGROUND

Rotaviruses are the major cause of severe childhood diarrhoea. Knowledge of the natural history of infection, including duration of intestinal virus shedding, is important in the understanding of transmission, sources of infection, and immune responses.

METHODS

We carried out a study of rotavirus excretion in 37 children admitted to hospital with severe rotavirus diarrhoea. Sequential faecal specimens were collected from each child during 100 days of surveillance, and screened for rotavirus by EIA and by amplification of genome double-stranded RNA by reverse-transcription PCR. IgA coproantibody was estimated by EIA.

FINDINGS

Duration of rotavirus excretion ranged from 4 to 57 days after onset of diarrhoea. Excretion ceased within 10 days in 16 (43%) children, and within 20 days in 26 (70%) children. Extended excretion was detected for 25-57 days in the remaining 11 (30%) children owing mainly to continued excretion of the primary infecting strain. Extended excretion was significantly associated with antirotavirus IgA coproantibody boosts during 100 days of surveillance (p=0.001, log-rank test), and with recurrence of mild diarrhoea symptoms during convalescence (p=0.006, Fisher's exact test).

INTERPRETATION

Severe rotavirus disease in young children may be followed by extended excretion of rotavirus. The risk of transmission to others may be greater than previously believed. Extended excretion could also explain some cases of the postgastroenteritis syndrome.

Acute and chronic diarrhoea and abdominal colic associated with enteroaggregative Escherichia coli in young children living in western Europe

BACKGROUND

Enteroaggregative Escherichia coli (EAggEC or EAEC) can spread and cause disease in developing countries, but it is not presently known whether it spreads disease in industrialised countries. Therefore, we did a prospective study to assess the incidence and the clinical manifestations of infections due to EAEC in children in Germany.

METHODS

798 children with diarrhoea, admitted to hospital within a defined geographical area during a 24-month period, were included in the trial. EAEC were cultured from stool specimens, screened by PCR, and identified by colony hybridisation from DNA sequences found on the virulence plasmid. The findings were confirmed by aggregative adherence to HEp-2 cells. Stool samples from 580 children admitted to hospital without diarrhoea were also studied as controls.

FINDINGS

EAEC were found in the stools of 16 (2%) of 798 children with diarrhoea, but in none of 580 children without diarrhoea. Only four of the EAEC-infected children had travelled to developing countries. Most EAEC infections were acquired in the summer months. Infection with EAEC was associated with acute, watery diarrhoea in 12 children, and with chronic diarrhoea of up to 5 months' duration in four. Five children had abdominal colic that lasted for 2-4 weeks as their main symptom. The incidence of EAEC infection was 7.7 patients admitted to hospital per 100,000 children in the general population aged younger than 16 years.

INTERPRETATION

EAEC infection is associated with acute, watery diarrhoea and may be acquired in industrialised countries. Chronic diarrhoea or abdominal colic of unknown aetiology in young children may also be caused by EAEC infection.

Lack of evidence for rotavirus by polymerase chain reaction/enzyme immunoassay of hepatobiliary samples from children with biliary atresia

The purpose of this study was to analyze hepatobiliary samples of patients with biliary atresia for rotavirus groups. A, B, and C, because group A rotavirus had been used to produce an animal model of the disease and group C rotavirus had been found in hepatobiliary samples from one group of patients. Biliary remnants and liver tissue from 10 biliary atresia and 14 control patients with other liver diseases were examined for rotavirus groups A, B, and C using nonisotopic, reverse transcriptase polymerase chain reaction enzyme immunoassay. Biliary atresia patients had a median age of 3 mo and were from a confined geographic area. Rotaviral stocks from groups A and C were used as polymerase chain reaction-positive controls. The limits of detection for rotaviral RNA from these two groups were respectively, 5 plaque-forming units and 50 tissue culture infectious doses (ID50). Tissue culture was 100-fold less sensitive for groups A and C than the polymerase chain reaction. The nested nonisotopic probes hybridized in solution only with their homologous target DNAs as determined by the enzyme immunoassay, or by Southern blot hybridization. Although it was possible to detect mRNA from a beta-actin housekeeping gene in all of the hepatobiliary samples, no evidence of rotaviral RNA was found in either the biliary atresia or the negative control group. In conclusion, rotavirus is not a common viral etiology of biliary atresia.

Evaluation of reverse transcription and polymerase chain reaction (RT/PCR) for the detection of rotaviruses: applications of the assay

Our aim was to evaluate the reverse transcription and polymerase chain reaction (RT/PCR) technique for the detection of rotavirus shedding by infected children as a routine diagnostic procedure, in comparison to the enzyme-linked immunosorbent assay (ELISA), electron microscopy (EM) and polyacrylamide gel electrophoresis (PAGE) of rotavirus double-stranded RNA. Two-hundred and twenty stool specimens were collected from infants and young children with diarrhoea, and 10-20% faecal suspensions were made. Several methods of rotavirus dsRNA extraction were assayed. Electrophoretic analysis of viral RNA was carried out on 10% polyacrylamide gels followed by silver staining. RT/PCR was performed using oligonucleotide primers specific for both 3' and 5' ends of the rotavirus gene encoding VP7 which are highly conserved among group A rotaviruses. Following RNA extraction with phenol-chloroform and ethanol precipitation, RT/PCR could detect rotaviral RNA in only 11 of 25 samples known to contain rotaviruses by conventional methods. The purification of RNA extracts by CF11 cellulose and the application of the RNAID method were equally effective in extracting RNA and/or removing inhibitory substances from the faecal samples. RT/PCR led to the detection of 66 positive samples from 220 specimens tested (30%), whilst 64 specimens were positive by ELISA (29%), 59 (26.8%) by PAGE and 56 (25.4%) by EM. In our study, RT/PCR was 100 times more sensitive than the ELISA test in detecting rotaviruses serially diluted in a faecal suspension. Although RT/PCR is theoretically much more sensitive than ELISA, PAGE and EM for detection of rotaviruses, great care must be taken to remove inhibitory substances from the enzymatic reactions. We do not consider that RT/PCR should replace immunoassays with high sensitivity and specificity for rotavirus testing in faecal samples, although this technique has other applications, like the search for rotavirus in different clinical specimens (sera, cerebrospinal fluid, respiratory secretions, etc.) and in environmental samples, as well as the typing of viral strains using serotype-specific primers.