First report of human astrovirus MLB2 in Brazil detected in feces of children with acute gastroenteritis living in the state of Roraima, Northern Brazil

ABSTRACT Human astrovirus (HAstV) 1-8 and highly divergent HAstVMLB1−3 genotypes have been detected in children both with and without acute gastroenteritis (AGE). One hundred and seventy fecal samples from children (≤5 years old) living in the Amazon region were evaluated for the presence of HAstV1-8, HAstV MLB1−3 and HAstVVA1−3, using an usual RT-PCR protocol and a new protocol with specific primers designed to detect HAstVMLB1−3. HAstVMLB1 and HAstV MLB2, as well as the HAstV3 and 5 genotypes were detected. HAstVMLB1−2 genotype was detected for the first time in Brazil at a frequency of 3.5% (6/170).

Caracterización molecular de calicivirus aislados de brotes de gastroenteritis ocurridos en la Argentina durante los años 2005 y 2006 / Molecular characterization of calicivirus strains detected in outbreaks of gastroenteritis occurring in Argentina during 2005 and 2006

Con el objetivo de determinar la incidencia de calicivirus, rotavirus y astrovirus en brotes de gastroenteritis ocurridos en diversas regiones de la Argentina durante los años 2005 y 2006, se analizaron muestras de materia fecal provenientes de 7 brotes con resultado de coprocultivo negativo. Para el diagnóstico de rotavirus se utilizó un ELISA comercial, mientras que para el diagnóstico de calicivirus y astrovirus se utilizó el método de RT-PCR. De las 74 muestras analizadas, 20 fueron positivas para calicivirus, 17 para rotavirus y una para astrovirus. No se identificaron infecciones virales mixtas. En 5 muestras positivas para calicivirus se secuenció una región del gen de la polimerasa; 4 de ellas correspondieron al género Norovirus y una al género Sapovirus. El análisis filogenético de las muestras secuenciadas determinó la presencia de norovirus de los genogrupos GI y GII; dentro de este último, se identificaron los genotipos GII-4, GII-b y GII-17. El análisis de la muestra en la cual se identificó sapovirus reveló la presencia del genotipo GI-1. Este estudio representa una continuación del análisis epidemiológico molecular de calicivirus asociados a brotes de gastroenteritis iniciado en 2004 y constituye la primera comunicación de la circulación de norovirus del genotipo GII-17 en la Argentina.

In order to determine the incidence of calicivirus, rotavirus and astrovirus in outbreaks of gastroenteritis occurring in different regions of Argentina during 2005 and 2006, fecal samples from seven nonbacterial outbreaks were analyzed. A commercial ELISA was used for rotavirus detection, while RT-PCRs were used for calicivirus and astrovirus. Of the 74 samples analyzed, 20 were calicivirus positive, 17 were rotavirus positive and one was astrovirus positive. No mixed infections were detected. A partial region of the RdRp gene was sequenced in five calicivirus positive-samples; 4 of them belonged to Norovirus genus and one to Sapovirus genus. The phylogenetic analysis of norovirus-positive-samples revealed the presence of strains from genogroups GI and GII; genotypes GII- 4, GII-b and GII-17 were identified within the latter. Phylogenetic the sapovirus-positive-sample revealed the presence of genotype GI-1. This study represents a follow-up of the of molecular epidemiology analysis of calicivirus associated to gastroenteritis outbreaks that have been carried out by our group since 2004, and constitutes the first report of the circulation of genotype GII-17 in Argentina.

Adenovirus, calicivirus and astrovirus detection in fecal samples of hospitalized children with acute gastroenteritis from Campo Grande, MS, Brazil

We analyzed fecal samples from hospitalized children up to three years of age with acute gastroenteritis at Campo Grande, Mato Grosso do Sul, Brazil, from May 2000-January 2004. Astrovirus and calicivirus were detected by Reverse Transcription-Polymerase Chain Reaction and adenovirus was detected using the Rotavirus and Adenovirus combined immunoenzyme assay. Astrovirus, adenovirus and calicivirus were detected at rates of 3.1 percent, 3.6 percent and 7.6 percent, respectively. These results re-emphasize the need for the establishment of regional vigilance systems to evaluate the impact of enteric viruses on viral gastroenteritis.

Coinfection of Viral Agents in Korean Children with Acute Watery Diarrhea

Currently, there are a few reports on viral coinfection that causes an acute watery diarrhea in Korean children. So, to evaluate the features of coinfectious viral agents in children with acute watery diarrhea, we enrolled 155 children with acute watery diarrhea from July 2005 to June 2006. Fecal samples were collected and evaluated for various viral infections such as rotavirus, norovirus, adenovirus and astrovirus. The mean (+/-standard deviation) age of the children was 2.71+/-2.37 yr. The detection rate of viral agents was most common in children between the ages of 1 and 3 yr. Rotavirus was detected in 63 children (41.3%), norovirus in 56 (36.2%), adenovirus in 11 (7.1%), and astrovirus in 1 (0.6%). Regarding rotavirus, there were 38 (60.3%) cases with monoinfection and 25 (39.7%) with coinfection. For norovirus, there were 33 (58.9%) cases with monoinfection and 23 (41.1%) with coinfection. Coinfection with rotavirus and norovirus was most common, and occurred in 20/155 cases (12.9%) including coinfection with adenovirus. So, rotavirus and norovirus were the most common coinfectious viral agents in our study population with acute watery diarrhea.

Molecular characterization of astrovirus in stool samples from children in São Paulo, Brazil

The purpose of this study was to characterize astrovirus in faecal samples collected from children with and without diarrhea in São Paulo, Brazil, grouped into two sets: EPM and HU. Detection and genotyping were carried out using reverse transcription nested polymerase chain reaction (RT-PCR) with specific primers directed towards the genome open reading frame 2 (ORF2). Results for EPM set showed that 66/234 (28.2 percent) were positive: 28/94 (29.7 percent) from children with acute diarrhea, 14/45 (31.1 percent) with persistent diarrhea, and 9/55 (16.3 percent) from control individuals. No data was available for 15/40 (37.5 percent) of samples. Mixed infections with other viruses were found in 33 samples. In the HU, 18/187 (9.6 percent) were positive: 12/158 (7.6 percent) from individuals with acute diarrhea and 6/29 (20.7 percent) from control children. Four samples were mixed with other viruses. Out of 66 astrovirus positive EPM samples, 18 (27.2 percent) were characterized as human astrovirus type-1 (HAstV-1), two (3.0 percent) as HAstV-2, two (3.0 percent) as HAstV-3, and three (4.5 percent) as HAstV-8. Among 18 astrovirus positive HU samples, one (5.5 percent) was characterized as HAstV-1, six (33.3 percent) as HAstV-2, and one (5.5 percent) as HAstV-8. Two HAstV-8 genotyped samples were further confirmed by nucleotide sequencing. Our results shows that astroviruses are circulating in a constant manner in the population, with multiple serotypes, in higher frequency than it was described for other Brazilian regions. For the first time in Sao Paulo, Brazil, it was shown that astroviruses play an important role in children gastroenteritis, as described for most locations where they were detected.

First detection of a human astrovirus type 8 in a child with diarrhea in Belém, Brazil: comparison with other strains worldwide and identification of possible three lineages

This study describes the genetic relationships of the first human astrovirus type-8 (HAstV-8) detected in Belém-Brazil, during a public hospital-based study. This strain was compared with other HAstV-8 strains identified elsewhere which have sequences available at GeneBank. The regions ORF1a (primers Mon348/Mon340) and ORF2 (primers Mon269/Mon270) were analyzed by nucleotide sequencing and a high similarity rate was observed among the Belém strain and other HAstV-8 strains. In ORF1a, homology values of 93-100 por cento were detected, and in ORF2 96-99 por cento. Considering the sequence variation (7 por cento) observed in ORF2 region, it was suggested that HAstV-8 strains could be divided in three different lineages.

Astrovirus infection in children living in the Central West region of Brazil

This study presents data regarding the circulation of astrovirus in Goiânia-GO and Brasília-DF. These viruses were detected in fecal samples from hospitalized children up to five years old with and without acute gastroenteritis. A total of 1244 fecal samples were collected in two periods, 1994 to 1996 (Brasília) and 1998 to 2002 (Goiânia and Brasília), and were analyzed for viral RNA using the reverse transcription-polymerase chain reaction (RT-PCR). Positivity rates of 4.3 and 0.5 percent for astrovirus were observed in children with acute gastroenteritis and those without gastroenteritis, respectively. Among children with gastroenteritis no statistically significant difference was seen with regards to viral positivity rates in relation to gender and age. However, a higher incidence rate was observed for children from Brasília aged 36 months or more. Overall, astroviruses occurred predominantly from September to March in the two cities, suggesting a seasonal pattern for these viruses which coincides with the highest relative air humidity period. The results of this study highlight the importance of astrovirus as an etiologic agent of acute gastroenteritis in children of the Central West region of Brazil.

Prevalence and genetic diversity of astroviruses in children with and without diarrhea in São Luís, Maranhão, Brazil

Human astroviruses (HAstV) have been increasingly identified as important etiological agents of acute gastroenteritis in children up to five years old. The aim of this study was to determine the prevalence and genotype diversity of HAstV in children with symptomatic and asymptomatic infections in São Luís, Maranhão, Brazil. From June 1997 to July 1999 a total of 183 fecal samples 84 from symptomatic and 99 from asymptomatic children were tested by enzyme immunoassay for HAstV. Prevalence rates were found to be 11 and 3 percent for symptomatic and asymptomatic children, respectively. Reverse transcription-polymerase chain reaction (RT-PCR) was carried out in 46 specimens (26 symptomatic and 20 asymptomatic) including the 12 samples that were positive by enzyme immunoassay (EIA). The overall positivity yielded by both methods was 8 percent (15/184); of these, 11 percent (9/84) for symptomatic and 5 percent (5/99) for those without symptoms or signs. Sequence analysis of amplicons revealed that HAstV-1 genotype was the most prevalent, accounting for 60 percent of isolates. Genotypes 2, 3, 4, and 5 were also detected, as one single isolate (10 percent) for each type. Variations in the sequences were observed when Brazilian isolates were compared to prototype strains identified in the United Kingdom. No seasonal pattern of occurrence was observed during these two years of study, and peak detection rate was observed in children aged between 3 and 6 months in the symptomatic group, and between 18 and 24 months in the controls.

An outbreak of gastroenteritis associated with astrovirus serotype 1 in a day care center, in Rio de Janeiro, Brazil

Between June 4th and June 20th1996 rotavirus, adenovirus, and astrovirus (HAstrV) were investigated in fecal samples from 27 children under three years old with acute diarrhea, attending the Bertha Lutz day care center, in Rio de Janeiro. All fecal samples were analyzed by polyacrylamide gel electrophoresis (PAGE), reverse transcriptase polymerase chain reaction (RT-PCR), enzyme immunoassays (EIA), and electron microscopy (EM). Nine of them (33 percent) showed positive results for HAstrV by at least one of the employed methodologies. Eight were positive by RT-PCR and EIA, and six by EM. All positive samples were inoculated onto HT-29 (human colon adenocarcinoma) cultured cells for HAstrV isolation and seven were positive after three passages. The sequencing analysis of eight RT-PCR products (449 bp) from gene that codifies VP2 protein, showed a total nucleotide identity among them and 98 percent with HAstrV-1 (strain Oxford type 1). This is the first report of a gastroenteritis outbreak associated with HAstrv-1 in a day care center in Rio de Janeiro and it reinforces the importance of this virus in association with infantile acute gastroenteritis

The epidemiology of acute viral gastroenteritis in hospitalized children in Cordoba city, Argentina: an insight of disease burden

Information concerning the disease burden of viral gastroenteritis has important implications for the use and monitoring the impact of public health policies. The present study, carried out in Córdoba city, Argentina, documents the epidemiology of severe viral diarrhea as well as the burden of viral gastrointestinal disease in the hospital children admission. A total of 133 stools were collected from hospitalized children (Town Childhood Hospital) suffering from acute diarrhea and studied for the presence of Group A rotavirus, astrovirus and adenovirus 40/41 by enzyme-immuno assay, between November 1997 and October 1998. Enteric viruses accounted for 42.1 percent of the total diarrheal cases analyzed. Group A rotaviruses, astroviruses, adenoviruses 40/41 and mixed infections were found in 35.3, 4.5, 1.5, and 0.8 percent studied specimens respectively. We estimated that 1 in 27 children in the 0-35 month-old cohort/range would be annually hospitalized for a viral gastroenteritis illness. The major impact on viral diarrhea lies on rotaviral infection, accouting for 84.0 percent of the viral diarrheal cases analyzed and for approximately one third of severe diarrheas requiring hospital admission in Córdoba City, Argentina