RESUMO
Human astroviruses (HAstVs) were detected in 23 stool samples from 365 diarrhea episodes among 214 children (<18 months old) prospectively monitored for diarrhea in Mexico City. Stool samples were tested by EIA and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. EIA was less sensitive (74%) and equally specific, compared with RT-PCR analysis using type-common primers for HAstV detection. Of 31 HAstV isolates, EIA typed 18 (69%) of 26 EIA-positive samples, and RT-PCR analysis typed 26 (84%) of 31 RT-PCR-positive samples. Phylogenetic analysis of the 3' end of the capsid region (363 nucleotides) confirmed the type assignment by EIA and RT-PCR analysis and determined the type for 5 previously untyped samples. Six HAstV antigenic types cocirculated in the community: HAstV-2 (42%), HAstV-4 (23%), HAstV-3 (13%), HAstV-1 (10%), HAstV-5 (6%), and HAstV-7 (6%). RT-PCR and sequence analysis provided more detailed epidemiology of HAstV in the community than did antigenic detection methods.
Assuntos
Infecções por Astroviridae/epidemiologia , Diarreia Infantil/epidemiologia , Mamastrovirus/classificação , Infecções por Astroviridae/virologia , Sequência de Bases , Células CACO-2 , Primers do DNA , Diarreia Infantil/virologia , Surtos de Doenças , Fezes/virologia , Feminino , Humanos , Técnicas Imunoenzimáticas , Lactente , Recém-Nascido , Masculino , Mamastrovirus/genética , Mamastrovirus/isolamento & purificação , México/epidemiologia , Epidemiologia Molecular , Dados de Sequência Molecular , Filogenia , Estudos Prospectivos , RNA Viral/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sensibilidade e Especificidade , Estudos Soroepidemiológicos , População Urbana/estatística & dados numéricosRESUMO
Nearly full-length genomic segments 2 and a partial-length genomic segment 1 of human picobirnavirus were cloned and sequenced. The clones were derived from viruses obtained from human immunodeficiency virus (HIV)-infected patients in Atlanta, Georgia (strains 3-GA-91 and 4-GA-91) and a nonHIV-infected person from China (strain 1-CHN-97). The picobirnavirus genomic segments lacked sequence similarities with other viral sequences in GenBank and EMBL. Comparison of genomic segment 1 from a human and a rabbit picobirnavirus identified a region of 127 nucleotides with 54.7% identity. The genomic segments 2 of the 4-GA-91 and 1-CHN-97 strains had 41.4% nucleic acid identity and 30.0% amino acid similarity and contained amino acid motifs typical of RNA-dependent RNA polymerase genes. Reverse transcription-PCR detection assays were developed with primers targeted to the genomic segments 2 of strains 4-GA-91 or 1-CHN-97. Picobirnaviruses related to the China strain were the predominant viruses detected in stool samples from people in four countries on three continents. Picobirnaviruses were detected in samples from two outbreaks of gastroenteritis in long-term elder care facilities but were not determined to be the primary pathogen. Our findings support the view that picobirnaviruses constitute a distinct family of viruses.
Assuntos
Fezes/virologia , Genes Virais , Infecções por Picornaviridae/virologia , Picornaviridae/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sequência de Aminoácidos , Argentina , Sequência de Bases , China/etnologia , Clonagem Molecular , Primers do DNA , Gastroenterite/epidemiologia , Gastroenterite/virologia , Infecções por HIV/virologia , Instituição de Longa Permanência para Idosos , Humanos , Dados de Sequência Molecular , Filogenia , Picornaviridae/classificação , Picornaviridae/isolamento & purificação , Infecções por Picornaviridae/diagnóstico , Infecções por Picornaviridae/epidemiologia , RNA Viral/análise , RNA Polimerase Dependente de RNA/genética , Alinhamento de Sequência , Estados Unidos/epidemiologia , VenezuelaRESUMO
The frequency of astrovirus infection in 456 Chilean children with diarrhea was determined by enzyme-linked immunosorbent assay, reverse transcriptase PCR, and cell culture. Astrovirus was detected in 16.5% of rotavirus-negative and 7% of rotavirus-positive samples obtained from emergency rooms or hospitals and in 11% of samples from day care centers. HAst-1 was the predominant serotype identified.
Assuntos
Infecções por Astroviridae/epidemiologia , Gastroenterite/virologia , Doença Aguda , Pré-Escolar , Chile/epidemiologia , Ensaio de Imunoadsorção Enzimática , Fezes/virologia , Humanos , Lactente , Recém-Nascido , PrevalênciaRESUMO
AIM: To describe the epidemiologic and clinical characteristics of astrovirus-associated diarrhea in a cohort of young children from a periurban community in Mexico City. METHODS: From November, 1988, through December, 1991, a total of 214 children were enrolled in a longitudinal study of diarrhea and monitored from birth to 18 months of age. A stool specimen was collected during each episode of diarrhea. Specimens from a total of 510 diarrhea episodes were tested for astrovirus by enzyme immunoassay and examined for other enteric pathogens. The antigenic types of astrovirus were determined by a typing enzyme immunoassay. RESULTS: Astrovirus was detected in 26 (5%) of 510 diarrhea episodes, with an incidence rate of 0.1 episode/child year; the highest rate was in children 13 to 18 months of age. Astrovirus-associated diarrhea was characterized by a median of 4 stools (range, 2 to 10) during the first 24 h, a median duration of 3 days (range, 1 to 21), vomiting (20%), and fever (7%). No cases of dehydration or repeat symptomatic infections were observed. Coinfection with another pathogen was detected in 11 of the 26 episodes (42%). Serotype 2 (35%) was most common, followed by serotypes 4 (15%), 3 (11%), and 1 and 5 (4% each); 31% were nontypable. Astrovirus-associated diarrhea was less severe, as measured by the number of stools (4.3 +/- 1.9), than diarrhea caused by rotavirus (7.1 +/- 2.8) or when coinfections occurred (5.5 +/- 1.6; P = 0.008). CONCLUSIONS: Astrovirus was associated with 5% of the episodes of diarrhea in this cohort of young Mexican children and presented as a mild secretory diarrhea. Five predominant antigenic types were detected with type 2 being the most common.
Assuntos
Infecções por Astroviridae/epidemiologia , Diarreia Infantil/epidemiologia , Diarreia Infantil/virologia , Mamastrovirus/isolamento & purificação , Infecções por Astroviridae/diagnóstico , Infecções por Astroviridae/fisiopatologia , Estudos de Coortes , Fezes/virologia , Feminino , Humanos , Técnicas Imunoenzimáticas , Lactente , Recém-Nascido , Estudos Longitudinais , Masculino , México/epidemiologia , Gravidez , Estudos ProspectivosRESUMO
The seroepidemiology of Norwalk virus infections was examined among Amerindians belonging to eight relatively isolated communities in the Amazon region by means of a new enzyme immunoassay using recombinant Norwalk virus antigen. The seroprevalence of antibodies to Norwalk virus ranged from 39% in the Maiogong to 100% in the Kubenkrankrein. The distribution of antibody levels varied greatly among groups; five of the eight communities had an antibody prevalence greater than 90% with many high values (> 100 units), while three had both a low seroprevalence and a preponderance of low values (< 100 units). While few children less than 5 years of age were sampled, no significant differences in antibody prevalence were noted among age groups, and the prevalence of antibody among children 5-10 years of age approached that of the older age groups. The low prevalence of titers of antibodies to Norwalk virus in several tribes living in these isolated Indian communities suggests that Norwalk virus may have been only recently introduced.
Assuntos
Anticorpos Antivirais/sangue , Infecções por Caliciviridae/epidemiologia , Gastroenterite/epidemiologia , Indígenas Sul-Americanos , Vírus Norwalk/imunologia , Adolescente , Adulto , Brasil/epidemiologia , Criança , Pré-Escolar , Humanos , Técnicas Imunoenzimáticas , Prevalência , Estudos Soroepidemiológicos , Venezuela/epidemiologiaRESUMO
OBJECTIVE: This study evaluated astrovirus as a cause of diarrhea outbreaks among infants and toddlers in day care centers. DESIGN: Stool specimens were collected weekly during four periods (from January 1986 through December 1991) from children 6 to 30 months of age who were enrolled in prospective studies of diarrhea in day care centers. All diarrheal stool specimens were tested for bacterial enteropathogens, rotavirus, enteric adenovirus, and Giardia lamblia. A total of 1365 stool specimens from 70 outbreaks in which no etiologic agent was identified and from another 11 outbreaks with a known cause were tested for astrovirus, by means of a monoclonal antibody-based enzyme immunoassay. Confirmatory testing was performed by reverse transcriptase-polymerase chain reaction with primers designed to produce an 89 base-pair product. RESULTS: Astrovirus was detected in 6 (7%) of the 81 outbreaks. Of 217 children tested, 73 (34%) were infected with astrovirus; infections in 35 (48%) were symptomatic and in 38 (52%) asymptomatic. The six outbreaks lasted 11 to 44 days (median 22 days). Astrovirus excretion was detected for a duration of 2 to 30 days, with excretion occurring from 1 to 8 days (median 2 days) before diarrhea began to 1 to 20 days (median 2 days) after diarrhea ceased. Younger children (< or = 12 months) were at greater risk than older children (p = 0.011) of becoming infected with astrovirus during an outbreak and were more likely (p = 0.015) to have symptoms when infected. Of 24 specimens with astrovirus by enzyme immunoassay, 20 (83%) were confirmed to have the virus by reverse transcriptase-polymerase chain reaction. CONCLUSION: Astrovirus was an important cause of outbreaks of diarrhea among children attending day care centers, more frequently infected younger children, and often produced asymptomatic infections.