Clinical surveillance for human astrovirus in Monastir region, Tunisia

Molecular characterization of human astrovirus infection in children under 5 years of age with acute gastroenteritis in Tehran, Iran, 2021-2022: co-infection with rotavirus

Human astroviruses (HAstVs) are considered important causative pathogens of acute gastroenteritis (AGE) in children under 5 years of age worldwide, along with group A rotavirus (RVA), norovirus (NoV), and enteric adenovirus (EAdV). The present study was aimed to both detect HAstV and its co-infections and investigate genetic analysis of circulating HAstV and co-infected virus in hospitalized children under 5 years of age with AGE in Iran. Accordingly, a sum of 200 stool specimens were screened by PCR for HAstV during 2021-2022. The HAstV was found in 0.5% of 200 specimens (n = 1) while was co-infected with RVA. The genetic and phylogenetic analysis indicated HAstV1 genotype, which clustered with viruses from lineage 1b, which has not been previously reported in Iran. The detected RVA strain belonged to G1 lineage II/P[8]-lineage III, which has been reported previously in Iran as the most common strain. The further genetic analysis of RVA VP6 and NSP4 demonstrated an atypical genotype pattern G1P[8]-I1-E2, as a mono-reassortant of a Wa-like genogroup, which appeared to be reassorted with the NSP4 gene of E2 genotype of the G2P[4] DS-1 genogroup. Although the clinical outcomes of the AGE-causing viruses co-infection is not yet entirely clear, it seems that future studies will be helpful to merge clinical and epidemiological data of co-infecting viruses for a more accurate medical and clinical relevance in symptomatic children.

Worldwide prevalence and genotype distribution of human astrovirus in gastroenteritis patients: A systematic review and meta-analysis

AIM

Human astrovirus (HAstV) is an important causative agent of gastroenteritis in humans, which mainly infects young children and the elderly. The goal of this study was to conduct a meta-analytic review of the prevalence of HAstV amongst patients with gastroenteritis, and to shed light on the connection between HAstV infection and gastroenteritis.

METHODS

Systematic literature searches were conducted to identify all potentially relevant studies recorded up to April 8th, 2022. For study weighting, the inverse variance method was employed and the random-effects model was applied to evaluate data. For case-control studies, the pooled odds ratio (OR) and 95% confidence interval (CI) were calculated to establish the relationship between HAstV infection and gastroenteritis.

RESULTS

Among 302423 gastroenteritis patients from 69 different countries, the overall pooled prevalence of HAstV infection was 3.48% (95% CI: 3.11%-3.89%). Case-control approach was used in 39 investigations, and the overall prevalence of HAstV infection among the 11342 healthy controls was 2.01% (95% CI: 1.40%-2.89%). Gastroenteritis and HAstV infection were associated with a pooled OR of 2.16 (95% CI: 1.72-2.71; P < 0.0001; I² = 33.7%). The most commonly found HAstV genotypes in gastroenteritis patients were HAstV1 (62.18%), HAstV7 (33.33%), and HAstV-MLB1 (17.43%).

CONCLUSION

The frequency of HAstV infection was the highest in children under the age of five, and in developing countries. The prevalence rate of HAstV was not influenced by gender. Semi-nested and nested RT-PCR were highly sensitive assays for detecting HAstV infections.

Human Astrovirus Outbreak in a Daycare Center and Propagation among Household Contacts

We investigated an outbreak of acute gastroenteritis due to human astrovirus in a daycare center, describing the transmission mechanism, the most affected age groups, conditioning factors and the extent of the outbreak among household contacts of the daycare center attenders. Data were collected from persons exposed at the daycare center and their home contacts. Fecal samples from affected and non-affected daycare center attenders were analyzed for viruses causing acute gastroenteritis by RT-PCR. The percentage of households affected and the attack rates (AR) were calculated. The attack rates were compared using the rate ratio (RR) with 95% confidence intervals. Information was obtained from 245 people (76 attenders and 169 contacts) of whom 49 were clinical cases. Five HAstV-4, two HAstV-8 and three non-typable HAstV cases were identified (six from clinical cases and four from asymptomatic infected people). The global AR was 20% (41.2% in children aged < 2 years). Data were obtained from 67 households: 20 households of affected attenders and 47 of non-affected attendees. Household contacts of affected attenders had a higher AR (74.3%) than that of non-affected attendees (2.4%). We found asymptomatic infections amongst daycare attendees. The transmission of HAstV during the outbreak was not limited to the daycare center but extended to household contacts of both affected and non-affected attenders.

Molecular epidemiology of astrovirus in children with gastroenteritis in southwestern Nigeria

Human astrovirus (HAstV) is recognized as one of the major causative agents of acute gastroenteritis in children worldwide. Data on the genetic diversity of HAstV in Nigeria are limited. The aim of this study was to determine the prevalence and molecular epidemiology of classical HAstV in children under 5 years of age with acute gastroenteritis in Ogun State, Nigeria. Fecal samples (331) as well as socio-demographic and clinical data were collected across the three senatorial districts of the state from February 2015 to April 2017. One hundred seventy-five samples were randomly selected and analyzed for the presence of HAstV using RT-PCR. PCR amplicons from positive samples were sequenced, and phylogenetic analysis was done to determine genotypes and lineages. The overall prevalence rate was 19.4% (34), with the highest occurrence observed in 2015 (41.4%). Viral coinfections were detected in 13 cases (38.2%). HAstV infection occurred throughout the year and in all age groups, mainly in the age group of 0-12 months. There was significant association between prevalence rate and collection year; however, no association was observed with gender, age, symptoms or risk factors. HAstV-5 was the predominant genotype (76.5%) circulating throughout the study period, followed by HAstV-1 (23.5%), which circulated only in the first 2 years of the study. Phylogenetic analysis showed that all HAstV-5 strains detected belonged to the 5a lineage, while HAstV-1 strains were grouped into lineage 1b. This study, to the best of our knowledge, is the first comprehensive report on molecular characterization of classical HAstV among children with gastroenteritis in the country, and this will serve as baseline information for implementing appropriate infection control practices.

Molecular Epidemiology of Human Astrovirus in Stool Samples From Patients With Acute Gastroenteritis in Korea, 2013-2017

Background

Human astroviruses (HAstVs) are one of the major causes of acute gastroenteritis. Classic HAstVs can be classified into eight genotypes. We investigated the positive rate of HAstVs and the distribution of HAstV genotypes in strains isolated from patients with acute gastroenteritis in Hwaseong, Korea, in 2013–2017.

Methods

Between November 2013 and December 2017, 3,519 stool samples were collected from patients with symptoms of acute gastroenteritis and tested for HAstV using multiplex PCR. For HAstV-positive samples, the ORF2 gene, which encodes a capsid protein, was genotyped by reverse-transcription PCR and sequencing. Phylogenetic analysis was performed to determine whether the sequences of the HAstVs differed by year.

Results

The positive rate of HAstV was 1.9% (67 samples). HAstV Type 1 was the most prevalent genotype (82.4%), and Types 4, 5, and 8 were also detected. Infection occurred year-round, with no distinct seasonal variation. Infection occurred at nearly all ages (55 days–81 years; median: 3 years), and the positive rate was substantially higher in children younger than five years. Phylogenetic analysis revealed three distinct clades of HAstV Type 1 according to the collection time.

Conclusions

Our results provide recent epidemiological data on HAstVs in Korea between 2013 and 2017. The finding of three distinct clades of HAstV Type 1 according to collection time suggests genetic evolution of HAstVs. These findings can enhance our knowledge on HAstV infection and viral evolution.

Epidemiology of human astroviruses among children younger than 5 years: Prospective hospital-based sentinel surveillance in South Africa, 2009-2014

BACKGROUND

The epidemiology of human astroviruses (HAstVs) in hospitalised patients less than 5 years of age from selected sites in South Africa was investigated. Diarrheagenic stool specimens collected from April 2009 to May 2014 were screened retrospectively for selected viruses, bacteria and parasites.

METHOD

Patient data were analysed to identify epidemiologic factors most frequently detected with HAstV infections. The following case-comparisons were investigated; HAstV-positive and HAstV-negative children, human immunodeficiency virus (HIV)-infected and HIV-uninfected (HAstV-positive) children and HIV-exposed and unexposed (HAstV-positive HIV-uninfected) children.

RESULTS

Astrovirus was identified in 7.0% (234/3340) of cases and most frequently in ages 7 to 12 months (9.2%; 90/975) compared with 5.8% to 6.6% in other 6-month age groups. No seasonal trends were observed. More HAstVs were detected in children from homes that used outdoor water sources (7.6%) compared to indoor sources [5.7%; adjusted odds ratio (aOR), 1.5; 95% CI, 1.1-2.1; P = 0.009]. Astroviruses were detected in 8.4% (67/799) of HIV-uninfected patients that were exposed to HIV compared with 5.9% (74/1257) of HIV-unexposed patients ( P = 0.032).

CONCLUSION

Astroviruses were most prevalent in children aged 7 to 12 months and were detected throughout the study period. The study was limited as only hospitalised patients were investigated and no comparisons were made to diarrhoea-free control groups. Future HAstV surveillance should include community-based studies and children presenting at outpatient facilities.

Epidemiology and genetic diversity of classic human astrovirus among hospitalized children with acute gastroenteritis in Uruguay

Classic Human Astrovirus (Classic HAstV) are one of the most important causes of pediatric acute gastroenteritis (AGE), after rotaviruses and arguably caliciviruses. The aim of this study was to determine the molecular epidemiology of Classic HAstV from 175 clinical samples, being 153 stools and 22 vomits, collected from pediatric hospitalized patients with AGE in Salto city, Uruguay, from January 2011 to December 2012. Classic HAstV were detected and genotyped by using a qualitative Retro Transcription-Polimerase Chain Reaction (RT-PCR) directed to the Open Reading Frame-2 (ORF2) region C. Amplicons were sequenced and phylogenetic analyses were carried out in order to determine genotypes and lineages. Classic HAstV were detected in 18 out of 175 analyzed samples (10.3%) and 14 of them (78.0%) were successfully sequenced being 6 (42.8%) classified as HAstV-1 (1a lineage), 4 (28.6%) as HAstV-2 (2c lineage), and 4 (28.6%) as HAstV-3 (3c lineage). A higher detection of Classic HAstV infections was observed in autumn for both years of surveillance, and the majority of the positive cases were observed in 2011. The group of children between 2 and 5 years old presented the higher percentage of infections. To our knowledge, the present study represents the first report of astrovirus from acute gastroenteritis cases in Uruguay, evidencing its role as a relevant etiologic agent in severe cases of this disease.

Characterization of astrovirus-associated gastroenteritis in hospitalized children under five years of age

PURPOSE

The aim of this study was to determine the incidence and genetic diversity of astrovirus (AstV) detected in children hospitalized for gastroenteritis (GE).

METHODS

A multi-center, hospital-based surveillance study was conducted across Lebanon to investigate the incidence of AstV among diarrheal hospitalizations. Viral RNA was extracted from stool samples collected between 2011 and 2013 from children, below the age of 5years, hospitalized for GE at six medical centers across Lebanon. Demographic and clinical data were collected and analyzed. RNA of eligible samples (n=739) was screened by two AstV-specific PCR assays followed by genotype-specific PCR. Sanger sequencing and phylogenetic analysis were performed for genotypic characterization.

RESULTS

Overall, 5.5% (41/739) of rotavirus-negative stool samples collected from hospitalized children <5years old tested positive for AstV infection. AstV infections were detected all year long. Diarrhea, dehydration, vomiting and fever were the most common symptoms associated with AstV infections. Children aged 48-59months had the highest incidence of AstV. Using the Vesikari Scoring System to assess clinical severity, 85.4% of children with AstV had a score>11, indicating severe GE. Genotype-specific PCR identified 22 classical and 4 MLB-like AstV specimens. Further sequencing and phylogenetic analysis of orf1b and orf2 genes revealed that AstV classical 1-3, 5, 6, and 8, MLB-1, VA-1 and -2 genotypes circulated in Lebanon. Recombination between classical AstV strains was detected in several cases as evident by the lack of congruency in the tree topologies of the orf1b and orf2. Two cases of mixed infections between classical and non-classical genotypic strains were recorded.

CONCLUSION

High genetic diversity was detected among AstVs in Lebanon. AstVs are associated with 5.5% of non-rotavirus GE-associated hospitalizations in children under five years in Lebanon.