Multilevel analysis of hepatitis A infection in children and adolescents: a household survey in the Northeast and Central-west regions of Brazil

Background The objectives were to estimate the prevalence of hepatitis A among children and adolescents from the Northeast and Midwest regions and the Federal District of Brazil and to identify individual-, household- and area-levels factors associated with hepatitis A infection. Methods This population-based survey was conducted in 20042005 and covered individuals aged between 5 and 19 years. A stratified multistage cluster sampling technique with probability proportional to size was used to select 1937 individuals aged between 5 and 19 years living in the Federal capital and in the State capitals of 12 states in the study regions. The sample was stratified according to age (59 and 10- to 19-years-old) and capital within each region. Individual- and household-level data were collected by interview at the home of the individual. Variables related to the area were retrieved from census tract data. The outcome was total antibodies to hepatitis A virus detected using commercial EIA. The age distribution of the susceptible population was estimated using a simple catalytic model. The associations between HAV infection and independent variables were assessed using the odds ratio and corrected for the random design effect and sampling weight. Multilevel analysis was performed by GLLAMM using Stata 9.2. Results The prevalence of hepatitis A infection in the 59 and 1019 age-group was 41.5 and 57.4, respectively for the Northeast, 32.3 and 56.0, respectively for the Midwest and 33.8 and 65.1 for the Federal District. A trend for the prevalence of HAV infection to increase according to age was detected in all sites. By the age of 5, 31.5 of the children had already been infected with HAV in the Northeast region compared with 20.0 in the other sites. By the age of 19 years, seropositivity was 70 in all areas. The curves of susceptible populations differed from one area to another. Multilevel modeling showed that variables relating to different levels of education were associated with HAV infection in all sites. Conclusion The study sites were classified as areas with intermediate endemicity area for hepatitis A infection. Differences in age trends of infection were detected among settings. This multilevel model allowed for quantification of contextual predictors of hepatitis A infection in urban areas.

The Impact of Vitamin A Supplementation on the Immune System of Vitamin A-deficient Children

Background & Aims: To investigate the effect of vitamin A supplementation on parameters of the immune system of vitamin A-deficient children. Methods: The study was carried out in four phases: 1) determination of serum retinol in 631 children from 36 to 83 months of age; 2) assessment of immunological markers [immunoglobulins and complement fractions, immunophenotyping of T and B lymphocytes, and natural killer (NK) cells], blood count, and serum ferritin of 52 vitamin A-deficient children (serum retinol <0.70 mu mol/L); 3) supplementation of the 52 deficient children with 200,000 IU of vitamin A; 4) determination of serum retinol and the immunological parameters 2 months after vitamin A supplementation. Results: Before vitamin A supplementation, 24.0% of the children were anemic and 4.3 %had reduced ferritin concentrations. There was no significant difference between mean values of retinol according to the presence/absence of anemia. The mean values of the humoral and cellular immunological parameters did not show a statistically significant difference before and after supplementation with vitamin A. Children with concomitant hypovitaminosis A and anemia presented a significant increase in absolute CD4 and CD8 T-cell counts after vitamin A supplementation (p < 0.05). Conclusion: Vitamin A had an effect on the recruitment of T and B lymphocytes to the circulation of children with hypovitaminosis A and anemia.

Fortified food made by the extrusion of a mixture of chickpea, corn and bovine lung controls iron-deficiency anaemia in preschool children

A fortified food that was rich in protein, vitamins and iron made of chickpea, bovine lung and corn was developed with the aim of controlling iron-deficiency anaemia in children from poorer areas. It was tested in Teresina, State of Piaui, Northeastern Brazil, on a population with high anaemia prevalence. Two local daycare units with similar characteristics were selected and the children at one of them received a 30 g pack three times a week, representing a total iron daily intake of 6.96 mg. The other daycare unit was followed as a control. The capillary haemoglobin concentration was determined for the children at both daycare units, at the beginning of the study and after a two-month intervention period. The mean haemoglobin concentration in the test group at the beginning of the intervention was 11.8 g/dL, which increased to 13.1 g/dL at the end of the intervention. In the control group these figures remained practically constant (11.6-11.8 g/dL). These represented a dramatic and significant drop in anaemia prevalence, from 61.5% to 11.5% in the test group, and an insignificant reduction (63.1-57.7%) in the control group. The acceptance of the fortified snack was excellent and no undesirable effects were observed. (C) 2007 Published by Elsevier Ltd.

Prevalence of untreated caries in deciduous teeth in urban and rural areas in the state of Sao Paulo, Brazil

Objectives. To describe the prevalence of dental caries in children with deciduous teeth in urban and rural areas in the state of Sao Paulo, Brazil, and to identify associated factors. Methods. The study included 24 744 children ( 5 - 7 years of age) examined as part of an epidemiological survey on oral health carried out in the state of Sao Paulo ( Levan-tamento Epidemiologico de Sa de Bucal do Estado de Sao Paulo). Multilevel analysis was used to investigate whether the prevalence of untreated caries was associated with the sociodemographic characteristics of the children examined or with the socioeconomic aspects of the participating cities. Results. Being black or brown ( adjusted odds ratio ( OR) = 1.27), attending school in rural areas ( adjusted OR = 1.88), and attending public school ( adjusted OR = 3.41) were identified as determinants for an increased probability of presenting deciduous teeth with untreated caries. Being a female ( adjusted OR = 0.83) was identified as a protective factor. The negative coefficients obtained for second- level independent variables indicate that the oral health profile of the cities included in the study were positively impacted by a higher municipal human development index ( beta = - 0.47) and fluoridated drinking water ( beta = - 0.32). Conclusions. The prevalence of untreated caries is influenced by individual and sociodemographic factors. The present study provides epidemiological information concerning the rural areas in the state of Sao Paulo. This information is useful for strategic planning and for establishing guidelines for oral health actions in local health systems, thereby contributing to oral health equity.

A multilevel model for the study of breastfeeding determinants in Brazil

The benefits of breastfeeding for the children`s health have been highlighted in many studies. The innovative aspect of the present study lies in its use of a multilevel model, a technique that has rarely been applied to studies on breastfeeding. The data reported were collected from a larger study, the Family Budget Survey-Pesquisa de Orcamentos Familiares, carried out between 2002 and 2003 in Brazil that involved a sample of 48 470 households. A representative national sample of 1477 infants aged 0-6 months was used. The statistical analysis was performed using a multilevel model, with two levels grouped by region. In Brazil, breastfeeding prevalence was 58%. The factors that bore a negative influence on breastfeeding were over four residents living in the same household [odds ratio (OR) = 0.68, 90% confidence interval (CI) = 0.51-0.89] and mothers aged 30 years or more (OR = 0.68, 90% CI = 0.53-0.89). The factors that positively influenced breastfeeding were the following: higher socio-economic levels (OR = 1.37, 90% CI = 1.01-1.88), families with over two infants under 5 years (OR = 1.25, 90% CI = 1.00-1.58) and being a resident in rural areas (OR = 1.25, 90% CI = 1.00-1.58). Although majority of the mothers was aware of the value of maternal milk and breastfed their babies, the prevalence of breastfeeding remains lower than the rate advised by the World Health Organization, and the number of residents living in the same household along with mothers aged 30 years or older were both factors associated with early cessation of infant breastfeeding before 6 months.

The impact of maternal cortisol concentrations on child arterial elasticity

Epidemiological studies suggest that glucocorticoid excess in the fetus may contribute to the pathophysiology of cardiovascular diseases in adulthood. However, the impact of maternal glucocorticoid on the cardiovascular system of the offspring has not been much explored in studies involving humans, especially in childhood. The objective of this study was to assess the influence of maternal cortisol concentrations on child arterial elasticity. One hundred and thirty pregnant women followed from 1997 to 2000, and respective children 5-7 years of age followed from 2004 to 2006 were included in the study. Maternal cortisol was determined in saliva by an enzyme immunoassay utilizing the mean concentration of nine samples of saliva. Arterial elasticity was assessed by the large artery elasticity index (LAEI; the capacitive elasticity of large arteries) by recording radial artery pulse wave, utilizing the equipment HDI/PulseWave CR-2000 Cardiovascular Profiling System (R). The nutritional status of the children was determined by the body mass index (BMI). Insulin concentration was assessed by chemiluminescence, and insulin resistance by the homeostasis model assessment. Blood glucose, total cholesterol and fractions (LDL-c and HDL-c) and triglyceride concentrations were determined by automated enzymatic methods. The association between maternal cortisol and child arterial elasticity was assessed by multivariate linear regression analysis. There was a statistically significant association between maternal cortisol and LAEI (P=0.02), controlling for birth weight, age, BMI and HDL-c of the children. This study suggests that exposure to higher glucocorticoid concentrations in the prenatal period is associated to lower arterial elasticity in childhood, an earlier cardiovascular risk marker.