Genetic Diversity of Norovirus Infections, Co-Infections, and Undernutrition in Children from Brazilian Semiarid Region.

BACKGROUND: Norovirus (NoV) infections are known to have high morbidity and mortality rates and are a major health problem globally. However, the impact of NoV on child development is poorly understood.

OBJECTIVE: 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 2-36 months from six cities of the Brazilian semiarid region. Fecal samples were collected from each child, along with the information regarding their socio-economic/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 ORF1-2 junction identified recombinant NoV strains in 80% of the sequenced samples. Enteroaggregative Escherichia coli co-infection 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).

CONCLUSION: This study highlights the genetic variability of NoV and, associated co-infections and undernutrition in infants from low-income Brazilian semiarid region.