Pediatric viral gastroenteritis during eight years of study

Challenges to Developing a Rotavirus Vaccine

Rotavirus is the most important cause of gastroenteritis worldwide. In developing countries, the virus is a major cause of death in infants and young children. In the United States, before the licensure of vaccines, rotavirus infections accounted for ∼2.7 million cases of gastroenteritis annually. Here are described the history and challenges surrounding the development of a rotavirus vaccine.

Randomised controlled trial of Lactobacillus rhamnosus (LGG) versus placebo in children presenting to the emergency department with acute gastroenteritis: the PECARN probiotic study protocol

INTRODUCTION

Acute gastroenteritis (AGE) is a common and burdensome condition that affects millions of children worldwide each year. Currently available strategies are limited to symptomatic management, treatment and prevention of dehydration and infection control; no disease-modifying interventions exist. Probiotics, defined as live microorganisms beneficial to the host, have shown promise in improving AGE outcomes, but existing studies have sufficient limitations such that the use of probiotics cannot currently be recommended with confidence. Here we present the methods of a large, rigorous, randomised, double-blind placebo-controlled study to assess the effectiveness and side effect profile of Lactobacillus rhamnosus GG (LGG) (ATCC 53103) in children with AGE.

METHODS AND ANALYSIS

The study is being conducted in 10 US paediatric emergency departments (EDs) within the federally funded Pediatric Emergency Care Applied Research Network, in accordance with current SPIRIT and CONSORT statement recommendations. We will randomise 970 children presenting to participating EDs with AGE to either 5 days of treatment with LGG (10¹⁰colony-forming unit twice a day) or placebo between July 2014 to December 2017. The main outcome is the occurrence of moderate-to-severe disease over time, as defined by the Modified Vesikari Scale. We also record adverse events and side effects related to the intervention. We will conduct intention-to-treat analyses and use an enrichment design to restore the statistical power in case the presence of a subpopulation with a substantially low treatment effect is identified.

ETHICS AND DISSEMINATION

Institutional review board approval has been obtained at all sites, and data and material use agreements have been established between the participating sites. The results of the trial will be published in peer-reviewed journals. A deidentified public data set will be made available after the completion of all study procedures.

TRIAL REGISTRATION NUMBER

NCT01773967.

Molecular analysis of norovirus in specimens from children enrolled in a 1982-1986 study in Belém, Brazil: A community-based longitudinal study

Fecal specimens were collected during a longitudinal, community-based study in the city of Belém, North Brazil, that was conducted over 3 years (October 1982 to March 1986), in which 20 children were included from birth to 3 years of age. A total of 229 fecal samples were screened by real time RT-PCR targeting the junction region (ORF 1/2) of the norovirus (NoV) genome. NoV-positive samples were subjected to PCR and sequencing of the viral polymerase (ORF1) and viral protein 1 (VP1) genes (ORF2). The junction region was also sequenced to assess for recombination when ORF1 and ORF2 genotyping results were dissimilar. Samples classified as GII.P4/GII.4 were further characterized by sequencing the P2 subdomain of the viral capsid to determine possible alterations. An overall positivity of 16.1% (37/229) was observed, including GI (16.2%-6/37) and GII (83.8%-31/37) genogroups. Cases of NoV reinfection in at least 2-month intervals were observed, and 12 children developed at least one case of asymptomatic NoV infection. In total, 48.6% (18/37) NoV-positive samples were subjected to nucleotide sequencing analysis targeting the following polymerase genes: GI.P3 (n = 1), GII.Pa (n = 1), GII.Pc (n = 1), GII.P4 (n = 5), GII.P6 (n = 5), GII.P7 (n = 3), GII.P12 (n = 1), and GII.P22 (n = 1). For the VP1 gene, characterization was performed in 14 (77.8%) samples: GI.3 (n = 1), GII.2 (n = 1), GII.4 (n = 4), GII.6 (n = 4), GII.7 (n = 1), GII.12 (n = 1), GII.14 (n = 1), and GII.23 (n = 1). Recombination events were confirmed in three cases (GII.P12/GII.2, GII.P7/GII.14, and GII.Pa/GII.12), and four samples genotyped as GII.P4/GII.4 were analyzed to identify variants. None had contemporary counterparts. Three children developed consecutive NoV infections by different genotypes. The present report documents the importance of NoV as a cause of childhood infection during a longitudinal study conducted more than 30 years ago.

Burden of Rotavirus Disease in Norway: Using National Registries for Public Health Research

BACKGROUND

Norway introduced routine rotavirus immunization for all children born on or after September 1, 2014. We estimated the healthcare burden of all-cause gastroenteritis and rotavirus disease in children <5 years old to establish the prevaccine baseline and support the ongoing immunization program.

METHODS

We examined national registry data on gastroenteritis-associated primary care consultations and hospitalizations for 2009-2013 and data on all deaths in children <5 years old reported during 2000-2013. We also established rotavirus hospital surveillance from February 2014 through January 2015.

RESULTS

Before vaccine introduction, 114.5 cases per 1000 children <5 years old were treated in primary care and 11.8 children per 1000 were hospitalized with gastroenteritis annually. During hospital surveillance, rotavirus was detected in 65% (95% confidence interval: 60-70) of inpatient gastroenteritis cases. We estimated that 4.0 inpatient and 2.3 outpatient cases per 1000 children were seen in hospital with rotavirus disease annually, suggesting that 1 in 32 children was hospitalized by age 5. Additional 30.6 rotavirus cases per 1000 children consulted primary care annually or 1 in every 7 children by the age of 5 years. Rotavirus-associated mortality was estimated at 0.17 deaths per 100,000 children <5 years old, corresponding to 1 death every second year.

CONCLUSIONS

Rotavirus remains the primary cause of severe gastroenteritis in children in Norway. The unique population-based registers, in combination with an established rotavirus surveillance platform, provide a well-suited setting to evaluate the impact of rotavirus vaccination.

Study on Rotavirus Infection and Its Genotyping in Children Below 5 Years in South West Iran

Background

Human rotaviruses are the most important agents for severe dehydrating diarrhea in children below 5 years old. Rotaviruses (RV) is a serious public health problem in developing and developed countries.

Objectives

The aim of this study was to determine the prevalence of rotavirus infection and their genotypes in children younger than 5 years of age with acute diarrhea in Ahvaz, Iran.

Materials and Methods

For this study, 200 stool samples from children below 5 years of age with acute diarrhea were collected between October 2011 and March 2012. Initially all stool samples were tested for rotavirus antigen by ELISA, and positive samples were confirmed by RT-PCR targeting the VP6 rotavirus gene. Determination of rotavirus genotypes was carried out by performing RT-PCR for G and P types. Altogether, 15 samples were sequenced.

Results

Out of 200 stool samples, 100 (50%) had rotavirus antigen detected by ELISA and 73 (36.5%) were found positive by RT-PCR. Of the rotavirus strains identified, only 63 (86.3%) were positive for both VP7 and VP4 while 10 (13.7%) strains were found nontypeable. Rotavirus infection accounts for 36.5% of gastroenteritis cases in samples from symptomatic children. The most prevalent rotavirus genotypes were G1P [8] (80%) followed by G2P [4] (20%).

Conclusions

Our results suggest that group A rotavirus is a major pathogene of acute diarrhea in Ahvaz city. The genotypes circulating are similar with those of other countries.

A universal infant rotavirus vaccine program in two delivery models: Effectiveness and adverse events following immunization

Rotavirus is the most common cause of diarrhea leading to hospitalization in young children. Rotavirus vaccines are available in Canada but have not been introduced in all provinces. In a controlled trial, 2 study sites (Prince Edward Island and the Capital District Health Authority (District 9, Nova Scotia) introduced universal rotavirus vaccine programs for infants at 2 and 4 months of age beginning 1 December 2010, using public health nurse or general practitioner-delivery models, respectively. A third site (Saint John, NB) served as the non-intervention control setting. Vaccine coverage, rotavirus hospitalizations, intussusception and all-cause diarrhea were monitored. A universal rotavirus vaccine program with >90% coverage was associated with reductions in rotavirus-associated hospitalizations (from a peak of 52.8 hospitalizations/100,000 population to 0 hospitalizations) in infants < 12 months and 1 to < 2 y of age 12 months after program implementation. No apparent reduction occurred in the site with vaccine coverage of < 40%, or in the non-intervention control site. No cases of intussusception were associated with vaccine receipt, and no increase in all-cause diarrhea was observed. A universal infant rotavirus vaccine program with high coverage was associated with reductions in rotavirus and no safety signals; no reduction was observed in settings with low vaccine coverage.

Analysis of human rotaviruses from a single location over an 18-year time span suggests that protein coadaption influences gene constellations

Rotaviruses (RVs) are 11-segmented, double-stranded RNA viruses that cause severe gastroenteritis in children. In addition to an error-prone genome replication mechanism, RVs can increase their genetic diversity by reassorting genes during host coinfection. Such exchanges allow RVs to acquire advantageous genes and adapt in the face of selective pressures. However, reassortment may also impose fitness costs if it unlinks genes/proteins that have accumulated compensatory, coadaptive mutations and that operate best when kept together. To better understand human RV evolutionary dynamics, we analyzed the genome sequences of 135 strains (genotype G1/G3/G4-P[8]-I1-C1-R1-A1-N1-T1-E1-H1) that were collected at a single location in Washington, DC, during the years 1974 to 1991. Intragenotypic phylogenetic trees were constructed for each viral gene using the nucleotide sequences, thereby defining novel allele level gene constellations (GCs) and illuminating putative reassortment events. The results showed that RVs with distinct GCs cocirculated during the vast majority of the collection years and that some of these GCs persisted in the community unchanged by reassortment. To investigate the influence of protein coadaptation on GC maintenance, we performed a mutual information-based analysis of the concatenated amino acid sequences and identified an extensive covariance network. Unexpectedly, amino acid covariation was highest between VP4 and VP2, which are structural components of the RV virion that are not thought to directly interact. These results suggest that GCs may be influenced by the selective constraints placed on functionally coadapted, albeit noninteracting, viral proteins. This work raises important questions about mutation-reassortment interplay and its impact on human RV evolution.

IMPORTANCE

Rotaviruses are devastating human pathogens that cause severe diarrhea and kill >450,000 children each year. The virus can evolve by accumulating mutations and by acquiring new genes from other strains via a process called reassortment. However, little is known about the relationship between mutation accumulation and gene reassortment for rotaviruses and how it impacts viral evolution. In this study, we analyzed the genome sequences of human strains found in clinical fecal specimens that were collected at a single hospital over an 18-year time span. We found that many rotaviruses did not reassort their genes but instead maintained them as specific sets (i.e., constellations). By analyzing the encoded proteins, we discovered concurrent amino acid changes among them, which suggests that they are functionally coadapted to operate best when kept together. This study increases our understanding of how rotaviruses evolve over time in the human population.

Molecular epidemiology of contemporary G2P[4] human rotaviruses cocirculating in a single U.S. community: footprints of a globally transitioning genotype

Group A rotaviruses (RVs) remain a leading cause of childhood gastroenteritis worldwide. Although the G/P types of locally circulating RVs can vary from year to year and differ depending upon geographical location, those with G1P[8], G2P[4], G3P[8], G4P[8], G9P[8], and G12P[8] specificities typically dominate. Little is known about the evolution and diversity of G2P[4] RVs and the possible role that widespread vaccine use has had on their increased frequency of detection. To address these issues, we analyzed the 12 G2P[4] RV isolates associated with a rise in RV gastroenteritis cases at Vanderbilt University Medical Center (VUMC) during the 2010-2011 winter season. Full-genome sequencing revealed that the isolates had genotype 2 constellations typical of DS-1-like viruses (G2P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2). Phylogenetic analyses showed that the genome segments of the isolates were comprised of two or three different subgenotype alleles; this enabled recognition of three distinct clades of G2P[4] viruses that caused disease at VUMC in the 2010-2011 season. Although the three clades cocirculated in the same community, there was no evidence of interclade reassortment. Bayesian analysis of 328 VP7 genes of G2 viruses isolated in the last 39 years indicate that existing G2 VP7 gene lineages continue to evolve and that novel lineages, as represented by the VUMC isolates, are constantly being formed. Moreover, G2 lineages are characteristically shaped by lineage turnover events that introduce new globally dominant strains every 7 years, on average. The ongoing evolution of G2 VP7 lineages may give rise to antigenic changes that undermine vaccine effectiveness in the long term.

IMPORTANCE

Little is known about the diversity of cocirculating G2 rotaviruses and how their evolution may undermine the effectiveness of rotavirus vaccines. To expand our understanding of the potential genetic range exhibited by rotaviruses circulating in postvaccine communities, we analyzed part of a collection of rotaviruses recovered from pediatric patients in the United States from 2010 to 2011. Examining the genetic makeup of these viruses revealed they represented three segregated groups that did not exchange genetic material. The distinction between these three groups may be explained by three separate introductions. By comparing a specific gene, namely, VP7, of the recent rotavirus isolates to those from a collection recovered from U.S. children between 1974 and 1991 and other globally circulating rotaviruses, we were able to reconstruct the timing of events that shaped their ancestry. This analysis indicates that G2 rotaviruses are continuously evolving, accumulating changes in their genetic material as they infect new patients.

Waterborne Viral Gastroenteritis: An Introduction to Common Agents

Acute gastroenteritis is among the most common illnesses of human beings, and its associated morbidity and mortality are greatest among those at the extremes of age; children and elderly. During the 1970s, several viruses were associated with this syndrome, which are now known to be caused mainly by viruses belonging to four distinct families—rotaviruses, caliciviruses, astroviruses, and adenoviruses. Other viruses, such as the toroviruses, picobirnaviruses, coronavirus, and enterovirus 22, may play a role as well. Transmission by food or water has been documented for astroviruses, caliciviruses, rotaviruses, and norovirus. In developing countries, gastroenteritis is a common cause of death in children <5 years, while deaths from diarrhea are less common, much illness leads to hospitalization or doctor visits. Laboratory confirmation of waterborne illness is based on demonstration of virus particles or antigen in stool, detection of viral nucleic acid in stool, or demonstration of a rise in specific antibody to the virus. Newer methods for syndrome surveillance of acute viral gastroenteritis are being developed like multiplex real-time reverse transcriptase PCRs. Application of these more sensitive methods to detect and characterize individual agents is just beginning, but has already opened up new avenues to reassess their disease burden, examine their molecular epidemiology, and consider new directions for their prevention and control through vaccination, improvements in water quality, and sanitary practices.

Rotavirus vaccines: successes and challenges

Since 2006, the availability of two new rotavirus vaccines has raised enthusiasm to consider the eventual control and elimination of severe rotavirus diarrhea through the global use of vaccines. Rotavirus remains the most severe cause of acute diarrhea in children worldwide responsible for several hundred thousands of deaths in low income countries and up to half of hospital admissions for diarrhea around the world. The new vaccines have been recommended by WHO for all infants and in more than 47 countries, their introduction into routine childhood immunization programs has led to a remarkable decline in hospital admissions and even deaths within 3 years of introduction. Challenges remain with issues of vaccine finance globally and the problem that these live oral vaccines perform less well in low income settings where they are needed most. Ongoing research that will accompany vaccine introduction might help address these issues of efficacy and new vaccines and novel financing schemes may both help make these vaccines universally available and affordable in the decade.

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.

The association of weather and bathing water quality on the incidence of gastrointestinal illness in the west of Scotland

The associations with weather and bathing water quality on infectious intestinal disease (IID) were investigated using data from two Scottish NHS Board areas. Monthly counts of viral and non-viral gastrointestinal infections were modelled as a smooth function of temperature, relative humidity and average monthly counts of faecal indicator organisms, respectively, adjusting for season and long-term trend effects. Strong seasonal patterns were observed for each group of pathogens. Peak viral gastrointestinal infection was in May while that of non-viral gastrointestinal infections was in July. A statistically significant negative association existed between weather (temperature and humidity) and viral infection. Average levels of non-viral gastrointestinal infections increased as temperature and relative humidity increased. Increasing levels of faecal indicator organisms in bathing waters were also associated with an increase in the average number of viral and non-viral gastrointestinal infections at the ecological level. Future climate change and prolonged precipitation events may result in increasing levels of faecal indicator organisms in bathing waters leading to likely increases in IIDs.

Rotavirus-associated hospitalization and emergency department costs and rotavirus vaccine program impact

OBJECTIVES

To determine the medical costs of laboratory-confirmed rotavirus hospitalizations and emergency department (ED) visits and estimate the economic impact of the rotavirus vaccine program.

PATIENTS AND METHODS

During 4 rotavirus seasons (2006-2009), children <3 years of age hospitalized or seen in the ED with laboratory-confirmed rotavirus were identified through active population-based rotavirus surveillance in three US counties. Medical costs were obtained from hospital and physician billing data, and factors associated with increased costs were examined. Annual national costs were estimated using rotavirus hospitalization and ED visit rates and medical costs for rotavirus hospitalizations and ED visits from our surveillance program for pre- (2006-2007) and post-vaccine (2008-2009) time periods.

RESULTS

Pre-vaccine, for hospitalizations, the median medical cost per child was $3581, the rotavirus hospitalization rate was 22.1/10,000, with an estimated annual national cost of $91 million. Post-vaccine, the median medical cost was $4304, the hospitalization rate was 6.3/10,000 and the estimated annual national cost was $31 million. Increased costs were associated with study site, age <3 months, underlying medical conditions and an atypical acute gastroenteritis presentation. For ED visits, the pre-vaccine median medical cost per child was $574, the ED visit rate was 291/10,000 resulting in an estimated annual national cost of $192 million. Post-vaccine, the median medical cost was $794, the ED visit rate was 71/10,000 with an estimated annual national cost of $65 million.

CONCLUSIONS

After implementation of rotavirus immunization, the total annual medical costs decreased from $283 million to $96 million, an annual reduction of $187 million.

Burden of rotavirus disease: A population-based study in Eastern Townships, Quebec

BACKGROUND

Since July 2010, the National Advisory Committee on Immunization of Canada has recommended rotavirus vaccination for all healthy infants. However, before implementing this vaccine in routine health programs, Canadian provinces need to establish current epidemiological data on rotavirus-associated acute gastroenteritis (AGE).

METHODS

A retrospective cohort study of children <5 years of age with AGE from 2002 to 2008 was performed in Eastern Townships, Quebec (population in 2006: 298,780). Data were collected on visits to outpatient clinics, emergency department (ED) visits, hospitalizations (standard and short-stay units) and nosocomial AGE. The winter residual estimation and Brandt methods were used to estimate the proportion of AGE attributable to rotaviruses.

RESULTS

During the six-year study period, a total of 1435 hospitalizations, 3631 ED visits and 6220 ambulatory care visits were attributed to AGE. The specific rotavirus burden was estimated to be 449 to 666 for hospitalizations, 1050 to 1361 for ED visits and 1633 to 1687 for outpatient visits. The epidemic curve showed a periodicity with higher incidence in March and April. Short-stay unit hospitalizations represented 58% of all hospitalizations. The annual incidence rate of rotaviruses was estimated to be 50 to 74 per 10,000 children for hospitalizations, 117 to 152 per 10,000 children for ED visits and 182 to 188 per 10,000 children for outpatient visits.

CONCLUSION

Most available retrospective studies probably underestimate rotavirus-associated hospitalizations because they do not take into account short-stay unit hospitalizations. Furthermore, these data on emergency and outpatient visits provide an exhaustive appraisal of the rotavirus burden, which serves as crucial information for the evaluation of immunization programs.

Rotavirus-related hospitalizations are responsible for high seasonal peaks in all-cause pediatric hospitalizations

BACKGROUND

Seasonal rotavirus (RV) epidemics partly overlap with those of other common childhood infections, thereby generating enormous, but poorly quantified, pressure on hospital resources during winter and spring. We assessed RV contribution to seasonal excess in all-cause pediatric hospitalizations and RV hospitalization incidence rate in an observational study.

METHODS

The study was conducted among pediatric wards in 3 general hospitals and 1 pediatric tertiary care center. Numbers of RV hospitalizations were determined from 5-year data on confirmed RV hospitalizations and adjusted for RV underreporting, assessed through active surveillance for acute gastroenteritis during the 2011 RV season. Incidence rate and RV contribution to all-cause hospitalizations were determined on hospital administrative data and population statistics.

RESULTS

RV accounted for 6.2% (95% confidence interval: 5.3-7.1) of all-cause pediatric hospitalizations among general hospitals and 3.1% (95% confidence interval: 2.9-3.3) at the tertiary care center, adjusted for the proportion RV underreporting among gastroenteritis patients (33%) as observed during active surveillance. Among general hospitals, there was a 30% increase in all-cause hospitalizations during the active season of common childhood infections compared with summer months. RV contributed 31% to seasonal excess in all-cause pediatric hospitalizations, representing 12.9% of hospitalizations between January and May. RV hospitalizations incidence rate in the population was 510/100,000 child-years <5 years (95% confidence interval: 420-600).

CONCLUSION

RV is one of the main causes of seasonal peaks in pediatric hospitalizations, and as such contributes significantly to periodic high bed capacity pressures and associated adverse effects. RV vaccination benefits in this respect should be considered in decision-making processes.

Burden of rotavirus hospitalisations in young children in three paediatric hospitals in the United States determined by active surveillance compared to standard indirect methods

AIM

  The number of rotavirus hospitalisations is usually estimated from assigned diagnosis codes for gastroenteritis despite lack of validation for these indirect methods. Reliable estimates before and after introduction of vaccines are needed to quantify the absolute impact of new immunisation programs.

METHODS

  This 2-year study conducted at three hospitals prior to the licensure of the rotavirus vaccines in the USA compared two indirect methods for estimating hospitalisations for rotavirus gastroenteritis with estimates derived from prospective recruitment of children presenting with diarrhoea, vomiting or fever. For active surveillance, rotavirus gastroenteritis was confirmed by demonstration of stool antigen. The indirect residual and proportional methods assumed rotavirus to have caused a proportion of hospitalisations coded as acute gastroenteritis identified from computerised records.

RESULTS

  There were 447 rotavirus hospitalisations among inpatients 31 days through 4 years of age admitted with vomiting and/or diarrhoea, compared with 306 and 228 hospitalisations identified by the two indirect methods. Only 52% of children hospitalised with gastroenteritis received a qualifying diagnosis code at discharge. Relative to active surveillance, the sensitivity and specificity (95% confidence interval (CI)) in identifying rotavirus-attributable hospitalisations was 45% (95% CI: 43-48%) and 89% (88-90%) for the residual method and 34% (30-39%) and 92% (90-94%) for the proportional method.

CONCLUSIONS

  Many children admitted to the hospital with diarrhoea, vomiting or fever were not assigned discharge codes for acute gastroenteritis. Consequently, standard indirect methods missed a substantial number of rotavirus-associated hospitalisations, thereby underestimating the absolute number of children who could potentially benefit from vaccination.

Epidemiologic and clinical features of other enteric viruses associated with acute gastroenteritis in American Indian infants

OBJECTIVE

To investigate the viral etiology, through the use of molecular methods, of acute gastroenteritis (AGE), which is a considerable public health burden in Native American infants.

STUDY DESIGN

From March 2002 through February 2004, AGE and non-diarrheal stools were collected from Navajo and White Mountain Apache infants who received placebo during a rotavirus vaccine trial. Case (n=247) and control (n=344) specimens were tested for enteric adenovirus, astrovirus, norovirus, rotavirus, and sapovirus with real-time polymerase chain reaction. The odds of AGE were compared with population-averaged logistic regression models.

RESULTS

In 65% of the cases of AGE (161/247), at least one virus was detected; norovirus (n=80, 32%) and rotavirus (n=70, 28%) were the most common. A virus was detected in 38% of control specimens (132/344). Detection of "any virus" was associated with AGE (OR=3.22; 95% CI, 2.11-4.91), as was detection of norovirus (OR=2.00; 95% CI, 1.22-3.26) and rotavirus (OR=2.69; 95% CI, 1.52-4.79).

CONCLUSION

This study highlights the significant burden of viral AGE in American Indian infants and identifies pathogen targets for future prevention efforts in this population.

The control of rotavirus gastroenteritis in the United States

Since 2006, two new vaccines have been licensed to prevent rotavirus, the cause of 20% to 50% of severe acute gastroenteritis in young children worldwide. These vaccines have been implemented in national immunization programs in about 30 high- and middle-income countries, including the United States, and vaccine use has led to substantial decreases in diarrhea-related health care visits. In addition to reductions in diarrhea burden in vaccinated children, decreases have been observed in older, unvaccinated age groups in many settings, suggesting indirect benefits (i.e., herd immunity) from vaccination. Although the efficacy of these oral rotavirus vaccines is expectedly lower in developing countries in Asia and Africa, the public health benefits of vaccination in these settings, where more than 90% of the estimated 453,000 annual deaths from rotavirus occur, are likely to be substantial. Efforts continue to develop alternative rotavirus vaccines that could have a better efficacy and safety profile and may be less expensive.

Hospitalizations for diarrhea in Quebec children from 1985 to 1998: estimates of rotavirus-associated diarrhea

OBJECTIVE

To characterize the incidence and duration of hospitalization due to diarrhea and to assess the proportion of hospitalizations that are attributed to rotavirus-associated diarrhea.

DESIGN

Retrospective study of hospitalization data.

SETTING

Hospitals located in Quebec.

POPULATION STUDIED

Children from one to 59 months of age who were discharged from hospital from April 1, 1985 to March 31, 1998.

MAIN RESULTS

There were 63,827 hospitalizations for diarrhea over the study period, for an average of 4910 hospitalizations/year. The epidemic curve showed a periodicity with regular alternation of high and low annual peaks. The number of hospitalizations for rotavirus-associated diarrhea was estimated according to three different methods. The estimates varied between 1353 and 1849 hospitalizations due to rotavirus-associated diarrhea/year over the 13-year period, with good agreement between the results of the three methods for a one-month to five years of age incidence of 320 hospitalizations for rotavirus-associated diarrhea/100,000 children. The average duration of hospital stay decreased from 5.2 days in 1985 to 3.3 days in 1998.

CONCLUSIONS

The present article shows the importance of diarrhea hospitalizations among children and the alternating peak-year periodicity.

Comparative evolution of GII.3 and GII.4 norovirus over a 31-year period

Noroviruses are the most common cause of epidemic gastroenteritis. Genotype II.3 is one of the most frequently detected noroviruses associated with sporadic infections. We studied the evolution of the major capsid gene from seven archival GII.3 noroviruses collected during a cross-sectional study at the Children's Hospital in Washington, DC, from 1975 through 1991, together with capsid sequence from 56 strains available in GenBank. Evolutionary analysis concluded that GII.3 viruses evolved at a rate of 4.16 × 10(-3) nucleotide substitutions/site/year (strict clock), which is similar to that described for the more prevalent GII.4 noroviruses. The analysis of the amino acid changes over the 31-year period found that GII.3 viruses evolve at a relatively steady state, maintaining 4% distance, and have a tendency to revert back to previously used residues while preserving the same carbohydrate binding profile. In contrast, GII.4 viruses demonstrate increasing rates of distance over time because of the continued integration of new amino acids and changing HBGA binding patterns. In GII.3 strains, seven sites acting under positive selection were predicted to be surface-exposed residues in the P2 domain, in contrast to GII.4 positively selected sites located primarily in the shell domain. Our study suggests that GII.3 noroviruses caused disease as early as 1975 and that they evolve via a specific pattern, responding to selective pressures induced by the host rather than presenting a nucleotide evolution rate lower than that of GII.4 noroviruses, as previously proposed. Understanding the evolutionary dynamics of prevalent noroviruses is relevant to the development of effective prevention and control strategies.

Weather variability and paediatric infectious gastroenteritis

Investigations of the relationship between weather variability and infectious gastroenteritis (IG) are becoming increasingly important in light of international interest in the potential health effects of climate change. However, few studies have examined the impact on children, despite the fact that children are considered particularly vulnerable to climate change. We acquired data about cases of IG in children aged <15 years and about weather variability in Fukuoka, Japan from 2000 to 2008 and used time-series analyses to assess how weather variability affected IG cases, adjusting for confounding factors. The temperature-IG relationship had an inverted V shape, with fewer cases at temperatures lower and higher than ~13°C. Every 1°C increase in temperature below the threshold (13°C) was associated with a 23·2% [95% confidence interval (CI) 16·6-30·2] increase, while every 1°C increase in temperature above the threshold (13°C) was associated with an 11·8% (95% CI 6·6-17·3) decrease in incidence. The increase in cases per 1% drop in relative humidity was 3·9% (95% CI 2·8-5·0). The percentage increase of IG cases was greatest in the 0-4 years age group and tended to decrease with increasing age. We found a progressive reduction in weather-related IG cases in children aged >4 years. Our results suggest that public health interventions aimed at controlling weather-related IG may be most effective when focused on young children.

Surveillance of rotavirus in a rural diarrhoea treatment centre in Bangladesh, 2000-2006

Rotavirus was detected in 33% of 4519 children less than 5 years of age admitted with diarrhoea to treatment centres at Matlab in rural Bangladesh from 2000 to 2006. Highest rotavirus detection rates were in children aged 6-11 months with 56% being less than 1 year old. The peak seasonal detection was in July-September and December-February. The population-based incidence rates of rotavirus ranged from 10.8 to 19.6/1000 children less than 5 years of age. G1 serotype predominated between June 2002-May 2005 and June 2005-May 2006 the predominant type was G2 (41%) followed by G1 (22%) and G9 (22%). Rotavirus is an important cause of childhood diarrhoea in rural Bangladesh and this burden may be reduced with a rotavirus vaccination programme.

Rotavirus disease and vaccination: impact on genotype diversity

Temporal and spatial fluctuations in the genotype distribution of human rotaviruses are continuously observed in surveillance studies. New genotypes, such as G9 and G12, have emerged and spread worldwide in a very short time span. In addition, reassortment events have the potential to contribute substantially to genetic diversity among human and animal rotaviruses. With the recent introduction of the two rotavirus vaccines, RotaTeq and Rotarix, in many countries, it appears that the total number of hospitalizations due to rotavirus infections is being reduced, at least in developed countries that implemented a universal immunization program. However, continued surveillance is warranted, especially regarding the long-term effects of the vaccines. No data analyses are available to clarify whether rotavirus vaccine introduction would allow other rotavirus P and G genotypes, which are not covered by the current vaccines, to emerge into the human population and fill the apparent gap. This kind of data analysis is essential, but its interpretation is hampered by natural and cyclical genotype fluctuations.

Estimated burden of rotavirus-associated diarrhea in ambulatory settings in the United States

BACKGROUND

Two vaccines to prevent disease from rotavirus among young children were recently approved in the United States. Although previous studies of the burden of rotaviral disease have focused on hospitalizations, the assessment of baseline disease burden in ambulatory settings is useful for evaluating the overall impact of the vaccine.

METHODS

Outpatient and emergency department (ED) data for 1994-2006 were analyzed from 2 nationally representative databases: the National Ambulatory Medical Care Survey and the National Hospital Medical Care Survey. Visits by children (younger than 5 years) with acute gastroenteritis (AGE) were identified by using a defined set of International Classification of Diseases, Ninth Revision, Clinical Modification codes. Two previously described methods (the winter-residual-excess [WRE] and Brandt methods) were used to estimate the proportion of AGE attributable to rotavirus and to determine the annual number of visits, annual average visits, and annual visit rates in each setting.

RESULTS

The estimated average annual number of rotavirus-associated visits over the 13-year period was 782 453 outpatient visits and 164 261 ED visits from the WRE method and 665 773 outpatient visits and 205 206 ED visits from the Brandt method. This resulted in an average of 39.1 and 33.3 outpatient visits per 1000 children and 8.2 and 10.3 ED visits per 1000 children for both the WRE and Brandt methods, respectively. The average annual proportion of visits for AGE attributed to rotavirus was 34.2% (29.1% from the Brandt method) in the outpatient setting and 21.8% (27.1% from the Brandt method) in the ED, with wide variations in individual years.

CONCLUSIONS

Before the rotavirus vaccine, rotavirus seemed to be associated with a large number of outpatient and ED visits among young children. Rotavirus vaccine has the potential to reduce many outpatient and ED visits.

Evolutionary dynamics of human rotaviruses: balancing reassortment with preferred genome constellations

Group A human rotaviruses (RVs) are a major cause of severe gastroenteritis in infants and young children. Yet, aside from the genes encoding serotype antigens (VP7; G-type and VP4; P-type), little is known about the genetic make-up of emerging and endemic human RV strains. To gain insight into the diversity and evolution of RVs circulating at a single location over a period of time, we sequenced the eleven-segmented, double-stranded RNA genomes of fifty-one G3P[8] strains collected from 1974 to 1991 at Children's Hospital National Medical Center, Washington, D. C. During this period, G1P[8] strains typically dominated, comprising on average 56% of RV infections each year in hospitalized children. A notable exception was in the 1976 and 1991 winter seasons when the incidence of G1P[8] infections decreased dramatically, a trend that correlated with a significant increase in G3P[8] infections. Our sequence analysis indicates that the 1976 season was characterized by the presence of several genetically distinct, co-circulating clades of G3P[8] viruses, which contained minor but significant differences in their encoded proteins. These 1976 lineages did not readily exchange gene segments with each other, but instead remained stable over the course of the season. In contrast, the 1991 season contained a single major clade, whose genome constellation was similar to one of the 1976 clades. The 1991 clade may have gained a fitness advantage after reassorting with as of yet unidentified RV strain(s). This study reveals for the first time that genetically distinct RV clades of the same G/P-type can co-circulate and cause disease. The findings from this study also suggest that, although gene segment exchange occurs, most reassortant strains are replaced over time by lineages with preferred genome constellations. Elucidation of the selective pressures that favor maintenance of RVs with certain sets of genes may be necessary to anticipate future vaccine needs.

The burden of rotavirus hospitalizations among Medicaid and non-Medicaid children younger than 5 years old

OBJECTIVES

We sought to compare the burden of hospitalizations associated with rotavirus gastroenteritis (RGE) in children younger than 5 years in US Medicaid and non-Medicaid populations in 2000 and 2003.

METHODS

We used the Kids' Inpatient Database (KID) to examine the burden of RGE-associated hospitalizations in terms of numbers and rates of hospitalizations, lengths of stay, and hospital charges. Two indirect methods were also used to estimate RGE-associated hospitalizations, because rotavirus testing is not routinely performed.

RESULTS

Approximately 40% of children younger than 5 years were enrolled in Medicaid in 2003, but this population accounted for nearly 50% of all RGE-associated hospitalizations and 60% of total charges. Children enrolled in Medicaid had significantly greater hospitalization rates, average lengths of stay, and average charges per stay than did those not enrolled.

CONCLUSIONS

Although RGE affects all socioeconomic groups, the Medicaid population accounted for a disproportionate number of the hospitalizations. With the inclusion of rotavirus vaccines in the pediatric immunization schedule, it is important that US children, especially those enrolled in Medicaid programs, are vaccinated to reduce the burden of RGE.

A capsid gene-based real-time reverse transcription polymerase chain reaction assay for the detection of marine vesiviruses in the Caliciviridae

A real-time reverse transcription polymerase chain reaction (rtRT-PCR) assay was developed for the identification of marine vesiviruses. The primers were designed to target a 176-nucleotide fragment within a highly conserved region of the San Miguel sea lion viruses (SMSVs) capsid gene. The assay detected viral RNA from nine marine vesivirus serotypes described previously, including two serotypes (SMSV-8 and -12) not identified with presently available molecular assays, a highly related bovine vesivirus strain (Bos-1), a mink vesivirus strain (MCV), and two novel genotypes isolated recently from Steller sea lions (SSL V810 and V1415). The real-time assay did not amplify sequences from the corresponding genomic regions of feline calicivirus (also in the genus Vesivirus) and representative members of the genus Norovirus. The rtRT-PCR assay described below may prove useful as a diagnostic tool for the detection of currently circulating, emerging and previously described marine vesiviruses in clinical samples, especially when large numbers are screened in surveillance studies of these restricted viruses.

Trends in healthcare utilization for diarrhea and rotavirus disease in privately insured US children <5 years of age, 2001-2006

BACKGROUND

To assess impact of the new US rotavirus immunization program initiated in 2006, robust baseline data on diarrhea and rotavirus disease burden are needed. While several studies have assessed burden in inpatient settings, few data are available for emergency department (ED) and outpatient settings.

METHODS

We used the MarketScan databases, a large claims-based data repository, to analyze the health and economic burden of diarrhea-related healthcare encounters in children <5 years in inpatient, ED, and outpatient settings from 2001 to 2006. Because rotavirus testing and coding are not routinely performed, rotavirus burden was estimated by calculating excess diarrhea events during winter compared with summer baseline (winter residual method).

RESULTS

Between 2001 and 2006, the average annual rate of healthcare utilization for diarrhea was 1561 per 10,000 children <5 years, with a hospitalization rate of 50 per 10,000, ED visit rate of 180 per 10,000, and outpatient visit rate of 1332 per 10,000. The winter residual method attributed 53% of inpatient, 41% of ED, and 23% of outpatient diarrhea events to rotavirus. By age 5, we estimated that 1 in 74 children are admitted, 1 in 27 require ED care, and 1 in 7 are treated in outpatient settings for rotavirus illness. Median payments for rotavirus in inpatient, ED, and outpatient settings were $3135, $332, and $90, respectively.

CONCLUSIONS

Rotavirus causes substantial health and economic burden in US children, especially in ED and outpatient settings. Future monitoring through claims-based data sources should allow assessment of rotavirus vaccine impact on healthcare utilization for diarrhea.

Evolutionary dynamics of GII.4 noroviruses over a 34-year period

Noroviruses are a major cause of epidemic gastroenteritis in children and adults, and GII.4 has been the predominant genotype since its first documented occurrence in 1987. This study examined the evolutionary dynamics of GII.4 noroviruses over more than three decades to investigate possible mechanisms by which these viruses have emerged to become predominant. Stool samples (n = 5,424) from children hospitalized at the Children's Hospital in Washington, DC, between 1974 and 1991 were screened for the presence of noroviruses by a custom multiplex real-time reverse transcription-PCR. The complete genome sequences of five GII.4 noroviruses (three of which predate 1987 by more than a decade) in this archival collection were determined and compared to the sequences of contemporary strains. Evolutionary analysis determined that the GII.4 VP1 capsid gene evolved at a rate of 4.3 x 10(-3) nucleotide substitutions/site/year. Only six sites in the VP1 capsid protein were found to evolve under positive selection, most of them located in the shell domain. No unique mutations were observed in or around the two histoblood group antigen (HBGA) binding sites in the P region, indicating that this site has been conserved since the 1970s. The VP1 proteins from the 1974 to 1977 noroviruses contained a unique sequence of four consecutive amino acids in the P2 region, which formed an exposed protrusion on the modeled capsid structure. This protrusion and other observed sequence variations did not affect the HBGA binding profiles of recombinant virus-like particles derived from representative 1974 and 1977 noroviruses compared with more recent noroviruses. Our analysis of archival GII.4 norovirus strains suggests that this genotype has been circulating for more than three decades and provides new ancestral strain sequences for the analysis of GII.4 evolution.

Cost of routine immunization of young children against rotavirus infection with Rotarix versus RotaTeq

Using a probabilistic model of the clinical and economic burden of rotavirus gastroenteritis (RVGE), we estimated the expected impact of vaccinating a US birth cohort with Rotarix in lieu of RotaTeq. Assuming full vaccination of all children, use of Rotarix - rather than RotaTeq - was estimated to reduce the total number of RVGE events by 5% and associated costs by 8%. On an overall basis, Rotarix would reduce costs by $77.2 million (95% CI $71.5-$86.5). Similar reductions with Rotarix were estimated to occur under an assumption of incomplete immunization of children.

Burden of acute gastroenteritis hospitalizations and emergency department visits in US children that is potentially preventable by rotavirus vaccination: a probe study using the now-withdrawn rotashield vaccine

BACKGROUND

With the implementation of a new rotavirus immunization program in the United States in 2006, determining the potential health benefits of rotavirus vaccination is important. We estimated the burden of acute gastroenteritis hospitalizations and emergency department visits in US children that are potentially preventable by rotavirus vaccination.

METHODS

We conducted a retrospective cohort analysis of children who in 1998-1999 were eligible to receive a now-withdrawn rotavirus vaccine (RotaShield) and were continuously enrolled in 1 of 6 managed care organizations in the Vaccine Safety Datalink. Estimates of vaccine effectiveness against all-cause gastroenteritis hospitalizations and emergency department visits adjusted according to month of birth, gender, and managed care organizations were calculated as 1 minus the risk ratio of outcomes among children in different dose groups. The burden of acute gastroenteritis prevented by vaccination was compared with the rotavirus burden estimated by 2 previously used indirect methods.

RESULTS

The effectiveness of a full 3-dose RotaShield series over a 1-year follow-up period was 83% against all-cause gastroenteritis hospitalizations and 43% against all-cause gastroenteritis emergency department visits. An increasing number of doses improved the effectiveness in preventing gastroenteritis hospitalizations, but no clear trend was observed between number of doses and effectiveness in prevention of gastroenteritis emergency department visits. The proportion of gastroenteritis hospitalizations and emergency department visits prevented by vaccination was substantially greater than the 48% to 53% of year-round hospitalizations and 33% of emergency department visits estimated to result from rotavirus by indirect methods.

CONCLUSIONS

The withdrawn rotavirus vaccine was highly effective in preventing hospitalizations and emergency department visits for all-cause acute gastroenteritis and the health benefits of vaccination against rotavirus may be greater than previously estimated.

The epidemiology of human rotavirus associated with diarrhoea in Kenyan children: a review

Rotavirus gastroenteritis still remains a major cause of morbidity and mortality among young children in developing countries, with approximately 150,000-200,000 deaths occurring annually in sub-Saharan Africa. We reviewed papers published over the last 30 years on the epidemiology of rotavirus diarrhoea among the hospitalized and out-patient children in Kenya. The analysis shows rotavirus prevalence of 6-56% with diarrhoea occurring throughout the year and generally exhibiting distinct peaks during the dry months. Among the common genotype, G1 was the most predominant up to the year 2002 but more recently there has been an emergence of genotype G9 as the most predominant genotype and to a less extent G8. It is important to continue rotavirus surveillance in Kenya to determine accurately the burden of rotavirus disease and the emerging new genotypes. This will assist policy makers in decision making on rotavirus vaccine introduction and determining the impact of the vaccine.

The VP7 genes of two G9 rotaviruses isolated in 1980 from diarrheal stool samples collected in Washington, DC, are unique molecularly and serotypically

In a retrospective study of archival diarrheal stool samples collected from 1974 to 1991 at Children's Hospital National Medical Center, Washington, DC, we detected three genotype G9P[8] viruses in specimens collected in 1980, which represented the earliest human G9 viruses ever isolated. The VP7 genes of two culture-adapted 1980 G9 viruses were phylogenetically related closely to the lineage 2 G9 virus VP7 gene. Unexpectedly, however, the VP7s of the 1980 G9 viruses were more closely related serotypically to lineage 3 VP7s than to lineage 2 VP7, which may be supported by amino acid sequence analyses of the VP7 proteins.

Cost-effectiveness analysis of vaccination against rotavirus with RIX4414 in France

BACKGROUND

It is estimated that annually 300 000 cases of rotavirus-induced gastroenteritis (RVGE) occur in children aged up to 5 years in France. A two-dose vaccine against rotavirus infection (RIX4414; Rotarix, GlaxoSmithKline), has been shown to be highly effective against severe RVGE.

OBJECTIVE

This study evaluated the cost effectiveness of general vaccination against rotavirus using RIX4414 in France.

METHODS

A Markov model simulated RVGE events and the associated outcomes and costs relating to general vaccination of infants against rotavirus infection using RIX4414 (Rotarix) in a birth cohort of children aged up to 5 years in France with a combined adjustment for age distribution with the seasonality of the infection. Costs and outcomes were estimated from a limited societal perspective, including direct medical costs paid out of pocket or by third-party payers, as well as the proportion of direct medical costs reimbursed by the health authorities. Indirect costs were not included in the base-case analysis. The primary outcome measure was the incremental cost per QALY.

RESULTS

Vaccination with RIX4414 incurred an incremental cost of 44 583 Euro per QALY at a public price of 57 Euro per vaccine dose. Univariate sensitivity analyses showed that the parameters with the largest influence on the results were the transition probabilities of severe diarrhoea, seeking medical advice and emergency visits, utility scores of diarrhoea (mild) in children and infants, and the discount rate for benefits. Probabilistic multivariate sensitivity analysis confirmed these results. The acceptability curve indicated that 94% of the results were under an informal threshold of 50 000 Euro per QALY. Comparing our results with those of a recently published study using pooled data for two rotavirus vaccine products in France, the main differences are explained by differences in model structure and in data input values. They include a different age distribution of the infection, shorter duration of the at-risk period (3 years instead of 5 years), different vaccine efficacy, different unit cost data, different disease duration, and different disutility values for the health states in the model. There is a need for agreed standards to improve comparability of results from different studies.

CONCLUSIONS

The results demonstrate that a generalized vaccination strategy with RIX4414 would be cost effective in France from a limited societal perspective, depending on the baseline assumptions for disease progression and on utility scores selected.

Rotavirus vaccines: an overview

Rotavirus infection is the most common cause of severe diarrhea disease in infants and young children worldwide and continues to have a major global impact on childhood morbidity and mortality. Vaccination is the only control measure likely to have a significant impact on the incidence of severe dehydrating rotavirus disease. In 1999, a highly efficacious rotavirus vaccine licensed in the United States, RotaShield, was withdrawn from the market after 14 months because of its association with intussusception. Two new live, oral, attenuated rotavirus vaccines were licensed in 2006: the pentavalent bovine-human reassortant vaccine (RotaTeq) and the monovalent human rotavirus vaccine (Rotarix). Both vaccines have demonstrated very good safety and efficacy profiles in large clinical trials in western industrialized countries and in Latin America. Careful surveillance has not revealed any increased risk of intussusception in the vaccinated groups with either vaccine. The new rotavirus vaccines are now introduced for routine use in a number of industrialized and developing countries. These new safe and effective rotavirus vaccines offer the best hope of reducing the toll of acute rotavirus gastroenteritis in both developed and developing countries.

Routine laboratory testing data for surveillance of rotavirus hospitalizations to evaluate the impact of vaccination

OBJECTIVE

The recent implementation of a rotavirus vaccination program in the United States makes it imperative to assess the impact of immunization on the incidence of severe rotavirus disease leading to hospitalization. Active surveillance for laboratory-confirmed rotavirus hospitalizations is the ideal approach for surveillance, but requires substantial resources to implement. We examined laboratory and hospital discharge data for 2 tertiary care pediatric hospitals to assess the utility of routine laboratory testing data for surveillance of rotavirus gastroenteritis and to estimate rotavirus disease burden.

DESIGN

We obtained all discharge records of hospitalizations for acute gastroenteritis among children <5 years of age at Children's Mercy Hospital (CMH), Kansas City, from July 2000 to June 2005 and at Children's Hospital of Philadelphia (CHOP) from July 2004 to June 2006. We linked these discharge records to laboratory results of rotavirus testing to evaluate epidemiologic differences in children who were tested and not tested for rotavirus and to estimate overall rotavirus burden by extrapolating clinical testing results to the untested group.

RESULTS

At CMH, of the 3702 children with acute gastroenteritis, 69% (n = 2552) were discharged during the winter (January through May) months, when rotavirus is most common. Similarly, at CHOP, 62% (n = 779) of the 1261 gastroenteritis discharges occurred during the winter months. During these months, 47% (n = 1197 of 2552) of the discharges at CMH and 56% (n = 438 of 779) of the discharges at CHOP were tested for rotavirus and of those tested, 71% (n = 853 of 1197) and 55% (n = 242 of 438) were positive, respectively. At both hospitals, children with and without rotavirus testing had similar gender and race/ethnicity, but the rate of testing differed by age at CHOP and by month of admission at CMH. After adjusting for these differences, we estimate that 56%-70% of winter and 34%-48% of year-round gastroenteritis in children <5 years can be attributable to rotavirus. Overall, 3%-5% of all hospitalizations in children <5 years of age were caused by rotavirus.

CONCLUSIONS

Sentinel hospitals where a large proportion of children hospitalized for gastroenteritis are routinely tested for rotavirus could provide a useful and cost-efficient platform to complement ongoing active surveillance efforts to evaluate the impact of rotavirus vaccination. The data reaffirm the substantial burden of rotavirus hospitalizations in US children and the potential health benefits of vaccination.

The diagnostic gap in diarrhoeal aetiology

It is well established that rotaviruses of group A are the most important cause of severe diarrhoea in children. The causes of most cases of infectious diarrhoea still remain unidentified, however, and there must be other viruses to be found. 'Novel' rotaviruses have recently been discovered, mainly in animals (serogroups B and C in pigs and humans, D in birds, and one or more further groups in sheep and other mammals). Except for the group B virus which has caused widespread outbreaks of quite severe diarrhoea in adults in China (still not reported from outside China) these novel rotaviruses are rarities in the human and probably represent uncommon zoonotic infections. We speculate that the Chinese virus might have arisen by reassortment of genetic segments of animal group B viruses or perhaps by mutation, and so became infectious for man. The problem of identifying and determining the importance of small round viruses is reviewed. It seems likely that the group of small, round structured viruses, including Norwalk and the viruses of plainly calicivirus morphology, are all representatives of a whole group of enteric caliciviruses. Until they can be more easily cultivated it will be difficult to make diagnostic reagents available to all. Astroviruses and genuine parvoviruses have been found by many people in many countries. Astroviruses are probably more important as pathogens in lambs than in children or calves; parvoviruses can only be established as significant in epidemics. The coronavirus-like particles, first found in Vellore and Bristol, are still enigmatic and their role in diarrhoea is uncertain. Toroviridae, recently discovered as causes of diarrhoea in ungulates, do not seem to be at all important as causes of diarrhoea in humans. Possibly fruitful approaches to future searches are outlined: firstly to make more extensive use of immuno-electron microscopy; and secondly to try to improve existing tissue culture systems to make them more sensitive to enteric viruses.

Nucleic acid-based analyses of non-group A rotaviruses

Simple genome profile studies on polyacrylamide gels allow all non-group A rotaviruses isolated so far to be recognized by the absence of the tight triplet (7-9) of RNA segments seen in all group A viruses. However, reliance solely on genome profile studies for rotavirus grouping can be misleading and, for virus group definition, additional corroborating nucleic acid and serological studies are essential. Terminal fingerprint analysis was the first generation of nucleic acid-based assays that allowed discrimination between the various rotavirus groups. By means of this technique the clear definition of five rotavirus groups (A-E), correlating exactly with those found by a serological assay, has been possible, with preliminary evidence for at least two additional groups. The technical sophistication of fingerprinting techniques prevents their widespread use in epidemiological studies; the development of a second generation of nucleic acid-based assays is therefore under way. These employ molecularly cloned cDNA probes to the genomes of non-group A viruses which can be widely distributed for use in 'dot-blot' screening of faecal samples and, if expressed as protein in Escherichia coli, should provide a ready source of viral antigen for use in surveying viral prevalence through the screening of serum antibody levels.

Characterization of a G11,P[4] strain of human rotavirus isolated in South Korea

A novel human rotavirus strain, CUK-1, containing a G11 type combined with a P[4] type was isolated from a 1-year-old female patient with fever and severe diarrhea at Our Lady of Mercy Hospital in Incheon, South Korea. This CUK-1 strain showed the highest degree of nucleic acid similarity (98.7% and 93%) to G11 Dhaka6 and P[4] RV 5, respectively. This novel combined type of CUK-1 rotavirus strain (G11,P[4]) was uncovered from humans and is reported on here for the first time.

Cost-effectiveness and potential impact of rotavirus vaccination in the United States

OBJECTIVE

In February 2006, a safe, efficacious, orally administered pentavalent human-bovine reassortant rotavirus vaccine was licensed and recommended for routine immunization of all children in the United States. We assessed the health and economic impacts of a national rotavirus immunization program in the United States.

METHODS

Monte Carlo cost-effectiveness analyses, from health care and societal perspectives, of vaccination of a hypothetical US birth cohort of 4,010,000 children monitored from birth to 59 months of age were performed. We compared the disease and economic burden of rotavirus infection in an unvaccinated cohort of children with one vaccinated at 2, 4, and 6 months with pentavalent human-bovine reassortant rotavirus vaccine.

RESULTS

A routine rotavirus immunization program would prevent 13 deaths, 44,000 hospitalizations, 137,000 emergency department visits, 256,000 office visits, and 1,100,000 episodes requiring only home care for children <5 years of age in the United States. Assuming costs of administration of $10, the break-even price per dose of vaccine was $42 from the societal perspective and $12 from the health care perspective. From the societal perspective, at the manufacturer's price of $62.50 per dose, vaccination would cost $138 per case averted, $3024 per serious case averted, and $197,190 per life-year saved, at a total cost of $515 million to the health care system and $216 million to society. Key variables influencing the results were parental workdays lost, costs of hospitalization, emergency department visits, and child care.

CONCLUSIONS

Despite a higher burden of serious rotavirus disease than estimated previously, routine rotavirus vaccination would unlikely be cost-saving in the United States at present. Nonetheless, rotavirus vaccination may still be considered a cost-effective intervention.

Climatic factors associated with hospitalizations for rotavirus diarrhoea in children under 5 years of age

This study compares the seasonality of rotavirus diarrhoeal hospital admissions and its relationship to climatic factors across three Australian cities. Weekly admission of rotavirus diarrhoea (1993-2003) in children aged <5 years and weekly average temperature and relative humidity for each city were modelled using a log-linear model with a cubic trend and season. Interactions were included to test for differences in the effect of temperature and humidity between seasons and between cities. Admissions of rotavirus diarrhoea peaked in winter and spring and were lowest in summer. Higher temperature and humidity in the previous week were associated with a decrease in rotavirus diarrhoeal admissions in three cities. The effects of both temperature and humidity on rotavirus admissions in Brisbane differed across seasons. Strategies to combat outbreaks of rotavirus diarrhoea should take climatic factors and seasonal effects into consideration to plan for the excess seasonal hospital admissions.