Etiology and severity of diarrheal diseases in infants at the semiarid region of Brazil: A case-control study

Background

Diarrheal diseases are an important cause of morbidity and mortality among children in developing countries. We aimed to study the etiology and severity of diarrhea in children living in the low-income semiarid region of Brazil.

Methodology

This is a cross-sectional, age-matched case-control study of diarrhea in children aged 2–36 months from six cities in Brazil’s semiarid region. Clinical, epidemiological, and anthropometric data were matched with fecal samples collected for the identification of enteropathogens.

Results

We enrolled 1,200 children, 596 cases and 604 controls. By univariate analysis, eight enteropathogens were associated with diarrhea: Norovirus GII (OR 5.08, 95% CI 2.10, 12.30), Adenovirus (OR 3.79, 95% CI 1.41, 10.23), typical enteropathogenic Escherichia coli (tEPEC), (OR 3.28, 95% CI 1.39, 7.73), enterotoxigenic E. coli (ETEC LT and ST producing toxins), (OR 2.58, 95% CI 0.99, 6.69), rotavirus (OR 1.91, 95% CI 1.20, 3.02), shiga toxin-producing E. coli (STEC; OR 1.77, 95% CI 1.16, 2.69), enteroaggregative E. coli (EAEC), (OR 1.45, 95% CI 1.16, 1.83) and Giardia spp. (OR 1.39, 95% CI 1.05, 1.84). By logistic regression of all enteropathogens, the best predictors of diarrhea were norovirus, adenovirus, rotavirus, STEC, Giardia spp. and EAEC. A high diarrhea severity score was associated with EAEC.

Conclusions

Six enteropathogens: Norovirus, Adenovirus, Rotavirus, STEC, Giardia spp., and EAEC were associated with diarrhea in children from Brazil’s semiarid region. EAEC was associated with increased diarrhea severity.

Most childhood diarrheal diseases studies focus on children from health centers or emergency hospitals that contribute to a lack of understanding of the etiology of community diarrhea. We aimed to investigate the etiology and severity of diarrheal diseases in children living in Brazil’s low-income, semiarid region communities. We used a case-control study of diarrhea (1,200 children, 596 cases and 604 controls) and showed that six enteropathogens (norovirus, adenovirus, rotavirus, STEC, Giardia and EAEC) are associated with diarrhea in these communities. Furthermore, enteroaggregative E. coli (EAEC) was associated with a high diarrhea clinical severity score. These findings help further the understanding of diarrheal disease etiology of previously unevaluated children from Brazil’s low-income semiarid region. This study contributes new information that expands our knowledge of diarrheal etiology in non-hospitalized children from developing countries. Moreover, we believe this work will support further research on specific enteropathogens, with special attention to the role of EAEC in severe cases of diarrhea and guide public health policies and physicians in the management of diarrheal diseases in Brazil’s low-income semiarid region.

Rotavirus A Infections in Community Childhood Diarrhea in the Brazilian Semiarid Region During Postvaccination Era

BACKGROUND

Rotavirus A (RVA) is one of the leading causes of acute gastroenteritis worldwide; however, few studies assessed RVA genetics with community surveillance.

OBJECTIVES

This study aimed to investigate clinical data, genetic diversity, and coinfection patterns of RVA infections in children from 2 to 36 months old with or without community childhood diarrhea in the Brazilian semiarid region during postvaccination era.

METHODS

We enrolled and collected socioeconomic/clinical information using a standardized questionnaire and fecal samples from 291 children. Viral RNA samples were extracted and analyzed using quantitative reverse transcription polymerase chain reaction to establish the diagnosis of RVA. Sequencing of VP7 and VP4 (VP8*) regions and phylogenetic analysis were performed.

RESULTS

RVA-negative diagnosis was associated with children 24 to 36 months old with complete vaccination schedule. Genotype G1P[8] was the most prevalent (57%), whereas unusual genotypes including G1P[4], G2P[8], and G3P[9] were also detected. G1- and P[8]-positive samples showed high degrees of similarity with the vaccine strain. RVA coinfections were frequently observed, and enteroaggregative Escherichia coli was the most prevalent copathogen.

CONCLUSIONS

These results demonstrate that genotype G1P[8] is the most prevalent strain. VP7 and/or VP8* gene segments arising from RV1 vaccine strain were documented in these children, suggesting shedding or herd vaccination. Moreover, our study indicates full vaccination is important for protection against RVA infections.