RESUMEN

BACKGROUND AND OBJECTIVE: Norovirus (NoV) infections are known to have high-morbidity and mortality rates and are a major health problem globally. The impact of NoV on child development is, however, poorly understood. We evaluated the distribution of NoV genotypes in children from a low-income Brazilian semiarid region, in relation with their clinical symptoms, nutritional status, and co-pathogens. METHODS: The test population included children aged 2 to 36 months from 6 cities of the Brazilian semiarid region. Fecal samples were collected from each child, along with the information regarding their socioeconomic/clinical conditions using a standardized questionnaire. Detection and quantification of NoV were performed by reverse-transcription quantitative polymerase chain reaction, followed by molecular and phylogenetic analyses. RESULTS: The NoV detection rate was 45.2%. Presence of NoV was associated with lower z scores for weight-for-age (P = 0.03), weight-for-height (P = 0.03), and body mass index-for-age (P = 0.03). NoV infection was associated with more frequent respiratory illnesses (P < 0.01). GII.P7 (polymerase) and GII.3 (capsid) were the most frequent NoV genotypes. Analysis of the open reading frame (ORF)1-2 junction identified recombinant NoV strains in 80% of the sequenced samples. Enteroaggregative Escherichia coli coinfection was the major predictor for diarrhea in NoV-positive samples (P < 0.02). Moreover, Shigella spp was also associated with NoV-positive diagnosis (P = 0.02). CONCLUSIONS: This study highlights the genetic variability of NoV and, associated co-infections and undernutrition in infants from low-income Brazilian semiarid region.

Asunto(s)

Infecciones por Caliciviridae/virología , Caliciviridae/genética , Trastornos de la Nutrición del Niño/virología , Coinfección/microbiología , Variación Genética , Estatura , Índice de Masa Corporal , Peso Corporal , Brasil/epidemiología , Infecciones por Caliciviridae/epidemiología , Infecciones por Caliciviridae/fisiopatología , Proteínas de la Cápside/análisis , Trastornos de la Nutrición del Niño/epidemiología , Preescolar , Coinfección/epidemiología , Diarrea/virología , Escherichia coli , Infecciones por Escherichia coli/epidemiología , Infecciones por Escherichia coli/virología , Heces/virología , Femenino , Genotipo , Humanos , Lactante , Masculino , Estado Nutricional , Filogenia , Reacción en Cadena en Tiempo Real de la Polimerasa , Shigella , Factores Socioeconómicos

RESUMEN

Host genetic resistance to Norovirus (NoV) has been observed in challenge and outbreak studies in populations from Europe, Asia, and USA. In this study, we have investigated if histo-blood group antigens can predict susceptibility to diarrhea caused by NoV in Nicaragua, Central America, and if this can be reflected in antibody-prevalence and titer to NoV among individuals with different histo-blood group antigen phenotypes. Investigation of 28 individuals infected with NoV and 131 population controls revealed 6% of non-secretors in the population and nil non-secretors among patients infected with NoV, suggesting that non-secretors may be protected against NoV disease in Nicaragua. Surprisingly, 25% of the population was Lewis negative (Le(a-b-)). NoV infections with genogroup I (GI) and GII occurred irrespective of Lewis genotype, but none of the Lewis a positive (Le(a + b-)) were infected. The globally dominating GII.4 virus infected individuals of all blood groups except AB (n = 5), while the GI viruses (n = 4) infected only blood type O individuals. Furthermore, O blood types were susceptible to infections with GI.4, GII.4, GII.7, GII.17, and GII.18-Nica viruses, suggesting that secretors with blood type O are susceptible (OR = 1.52) and non-secretors resistant. The overall antibody-prevalence to NoV GII.3 VLP was 62% with the highest prevalence among blood type B carriers (70%) followed by A (68%) and O (62%). All four investigated individuals carrying blood type AB were antibody-negative. Among secretors, 63% were antibody-positive compared to 33% among non-secretors (P = 0.151). This study extends previous knowledge about the histo-blood group antigens role in NoV disease in a population with different genetic background than North American and European.

Asunto(s)

Antígenos de Grupos Sanguíneos , Infecciones por Caliciviridae/genética , Gastroenteritis/genética , Predisposición Genética a la Enfermedad , Norovirus/patogenicidad , Sistema del Grupo Sanguíneo ABO , Adolescente , Adulto , Anticuerpos Antivirales/sangre , Infecciones por Caliciviridae/epidemiología , Infecciones por Caliciviridae/fisiopatología , Infecciones por Caliciviridae/virología , Niño , Preescolar , Codón sin Sentido , Fucosiltransferasas/genética , Gastroenteritis/epidemiología , Gastroenteritis/fisiopatología , Gastroenteritis/virología , Humanos , Lactante , Antígenos del Grupo Sanguíneo de Lewis , Persona de Mediana Edad , Nicaragua/epidemiología , Norovirus/clasificación , Norovirus/genética , Norovirus/inmunología , Prevalencia , Adulto Joven , Galactósido 2-alfa-L-Fucosiltransferasa

RESUMEN

BACKGROUND: The effect of vitamin A supplementation on viral gastrointestinal infections among young children living in developing countries remains unclear. METHODS: The effect of vitamin A supplementation on norovirus (NoV) infection among 127 Mexican children 5-15 months of age was studied in a randomized, placebo-controlled trial during June-August 1998. Stool samples collected every 2 weeks and after diarrheal episodes were screened for NoV and characterized at the genogroup level (GI and GII). RESULTS: Of the stool samples collected, 29.9% were positive for NoV, and NoV GI and NoV GII were found in 55.4% and 46.4% of the positive samples, respectively. Vitamin A supplementation reduced the prevalence of NoV GII infections (rate ratio [RR], 0.60 [95% confidence interval {CI}, 0.20-0.82]), increased the length of both NoV GI and GII shedding, and decreased the prevalence of NoV-associated diarrhea (RR, 0.51 [95% CI, 0.26-0.97]). CONCLUSIONS: These findings suggest that NoV is an important cause of pediatric diarrhea in this study population and that vitamin A supplementation has divergent effects on specific outcomes of NoV infection.

Asunto(s)

Infecciones por Caliciviridae , Gastroenteritis , Norovirus/efectos de los fármacos , Vitamina A , Infecciones por Caliciviridae/tratamiento farmacológico , Infecciones por Caliciviridae/epidemiología , Infecciones por Caliciviridae/fisiopatología , Heces/virología , Femenino , Gastroenteritis/tratamiento farmacológico , Gastroenteritis/epidemiología , Gastroenteritis/fisiopatología , Gastroenteritis/virología , Humanos , Lactante , Masculino , México/epidemiología , Norovirus/clasificación , Norovirus/aislamiento & purificación , Prevalencia , Resultado del Tratamiento , Vitamina A/administración & dosificación , Vitamina A/uso terapéutico , Vitaminas/administración & dosificación , Vitaminas/uso terapéutico

RESUMEN

Sixty-three children in periurban Mexico City were examined for the occurrence of asymptomatic norovirus (NoV) infection from June to August 1998. NoV was detected in 48 of 161 stool specimens (29.8%), with 31 children (49.2%) having at least one positive stool. Asymptomatic NoV infection occurred commonly during summertime in a Mexican pediatric population.

Asunto(s)

Infecciones por Caliciviridae/fisiopatología , Infecciones por Caliciviridae/virología , Heces/virología , Norovirus/aislamiento & purificación , Humanos , Lactante , Recién Nacido , México , Datos de Secuencia Molecular , Norovirus/genética , Filogenia , ARN Viral/análisis , ARN Viral/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Análisis de Secuencia de ADN , Homología de Secuencia , Población Urbana