Carlos A. Teles

Effect of city-wide sanitation programme on reduction in rate of childhood diarrhoea in northeast Brazil: assessment by two cohort studies

Summary Background A city-wide sanitation intervention was started in Salvador, Brazil, in 1997 to improve sewerage coverage from 26% of households to 80%. Our aim was to investigate the epidemiological effect of this city-wide sanitation programme on diarrhoea morbidity in children less than 3 years of age. Methods The investigation was composed of two longitudinal studies done in 1997–98 before the intervention (the sanitation programme) and in 2003–04 after the intervention had been completed. Each study consisted of a cohort of children (841 in the preintervention study and 1007 in the postintervention study; age 0–36 months at baseline) who were followed up for a maximum of 8 months. Children were sampled from 24 sentinel areas that were randomly chosen to represent the range of environmental conditions in the study site. At the start of each study an individual or household questionnaire was applied by trained fieldworkers; an environmental survey was done in each area before and after introduction of the sanitation programme to assess basic neighbourhood and household sanitation conditions. Daily diarrhoea data were obtained during home visits twice per week. The effect of the intervention was estimated by a hierarchical modelling approach fitting a sequence of multivariate regression models. Findings Diarrhoea prevalence fell by 21% (95% CI 18–25%)—from 9·2 (9·0–9·5) days per child-year before the intervention to 7·3 (7·0–7·5) days per child-year afterwards. After adjustment for baseline sewerage coverage and potential confounding variables, we estimated an overall prevalence reduction of 22% (19–26%). Interpretation Our results show that urban sanitation is a highly effective health measure that can no longer be ignored, and they provide a timely support for the launch of 2008 as the International Year of Sanitation.

Risk Factors for Childhood Diarrhea Incidence: Dynamic Analysis of a Longitudinal Study

Background: Several longitudinal studies have investigated factors associated with childhood diarrhea in developing countries. However, most studies have neglected important dynamic features of the longitudinal design and hierarchical interrelationships among the potential risk factors. Methods: We conducted a longitudinal study of 902 children, age 0 to 36 months at baseline, in a large urban center in northeastern Brazil. Diarrhea data were collected by following children from October 2000 until January 2002 with biweekly home visits. We used a dynamic time-to-event analysis to account for several longitudinal features. We applied an effect-decomposition strategy to quantify direct and indirect effects of risk factors grouped in different blocks. Results: Childs age and an autoregressive effect of past diarrhea episodes explained some of the decline of diarrhea incidence observed throughout the study (from more than 14 episodes to 2 episodes per child-year), a phenomenon already observed but not explained in other longitudinal diarrhea studies. We identified the following major diarrhea determinants: low socioeconomic status, poor sanitation conditions, presence of intestinal parasites, and absence of prenatal examination. The effect of socioeconomic status was mediated mostly by living and sanitation conditions. Conclusion: Our study shows important advantages of applying a dynamic analysis approach to longitudinal observational studies of diarrhea or other acute diseases and highlights the complex interrelationships of diarrhea determinants. Our results confirm the importance of sanitation as a major determinant of child health in urban settings of developing countries.

Impact of a citywide sanitation program in Northeast Brazil on intestinal parasites infection in young children.

Background Sanitation affects health, especially that of young children. Residents of Salvador, in Northeast Brazil, have had a high prevalence of intestinal parasites. A citywide sanitation intervention started in 1996 aimed to raise the level of sewer coverage from 26% to 80% of households. Objectives We evaluated the impact of this intervention on the prevalence of Ascaris lumbricoides, Trichuris trichuria, and Giardia duodenalis infections in preschool children. Methods The evaluation was composed of two cross-sectional studies (1998 and 2003–2004), each of a sample of 681 and 976 children 1–4 years of age, respectively. Children were sampled from 24 sentinel areas chosen to represent the range of environmental conditions in the study site. Data were collected using an individual/household questionnaire, and an environmental survey was conducted in each area before and after the intervention to assess basic household and neighborhood sanitation conditions. Stool samples were examined for the presence of intestinal parasites. The effect of the intervention was estimated by hierarchical modeling, fitting a sequence of multivariate regression models. Findings The prevalence of A. lumbricoides infection was reduced from 24.4% to 12.0%, T. trichuria from 18.0% to 5.0%, and G. duodenalis from 14.1% to 5.3%. Most of this reduction appeared to be explained by the increased coverage in each neighborhood by the sewage system constructed during the intervention. The key explanatory variable was thus an ecological measure of exposure and not household-based, suggesting that the parasite transmission prevented by the program was mainly in the public (vs. the domestic) domain. Conclusion This study, using advanced statistical modeling to control for individual and ecological potential confounders, demonstrates the impact on intestinal parasites of sanitation improvements implemented at the scale of a large population.

Impact of a city-wide sanitation intervention in a large urban centre on social, environmental and behavioural determinants of childhood diarrhoea: analysis of two cohort studies

BACKGROUNDnPoor socioeconomic status (SES) increases diarrhoea risk, mostly mediated by lack of sanitation, poor infrastructure and living conditions. The effectiveness of a city-wide sanitation intervention on diarrhoea in a large urban centre in Northeast Brazil has recently been demonstrated. This article aims to explore how this intervention altered the magnitude of relative and attributable risks of diarrhoea determinants and the pathways by which those factors affect diarrhoea risk.nnnMETHODSnWe investigated determinants of prevalence of diarrhoea in two cohort studies conducted before and after the intervention. Each study enrolled pre-school children followed up for 8 months. For both cohorts, we calculated relative, attributable and mediated risks of diarrhoea determinants by a hierarchical effect decomposition strategy.nnnRESULTSnThe intervention reduced diarrhoea and also changed attributable and relative risks of diarrhoea determinants by altering the pathways of mediation. Before the intervention SES was a major distal diarrhoea determinant (attributable risk: 24%) with 90% of risk mediated by other factors, mostly by lack of sanitation and poor infrastructure (53%). After the intervention, only 13% of risk was attributed to SES, with only 42% mediated by other factors (18% by lack of sanitation and poor infrastructure).nnnCONCLUSIONnThe intervention reduced diarrhoea risk by reducing direct exposure to unfavourable sanitation conditions. At the same time it altered the effect and mediation pathways of most distal diarrhoea determinants, especially SES. This finding corroborates the importance of public sanitation measures in reducing the impact of poverty on diarrhoea. It also underlines the value of studying the impact of public health interventions to improve our understanding of health determinants.

Urbanisation is associated with prevalence of childhood asthma in diverse, small rural communities in Ecuador

Background Studies conducted in transitional communities from Africa and Asia have pointed to the process of urbanisation as being responsible for the increase in asthma prevalence in developing regions. In Latin America, there are few published data available on the potential impact of urbanisation on asthma prevalence. The aim of the present study was to explore how the process of urbanisation may explain differences in asthma prevalence in transitional communities in north-eastern Ecuador. Methodology/principal findings An ecological study was conducted in 59 communities in Esmeraldas Province, Ecuador. Indicators of urbanisation were grouped into three indices representing the processes associated with urbanisation: socioeconomic, lifestyle and urban infrastructure. Categorical principal components analysis was used to generate scores for each index and a fourth index—a summary urbanisation index—was derived from the most representative variables in each of the three indices. The authors analysed the associations between community asthma prevalence and the indices, as well as with each indicator variable of every group. The overall prevalence of asthma was 10.1% (range 0–31.4% between communities). Three of the four indices presented significant associations with community asthma prevalence: socioeconomic (r=0.295, p=0.023), lifestyle (r=0.342, p=0.008) and summary urbanisation index (r=0.355, p=0.006). Variables reflecting better socioeconomic status and a more urban lifestyle were associated with greater asthma prevalence. Conclusions These data provide evidence that the prevalence of asthma increases with increasing levels of urbanisation in transitional communities, and factors associated with greater socioeconomic level and changes towards a more urban lifestyle may be particularly important.

Impulsivity is relevant for trauma exposure and PTSD symptoms in a non-clinical population

Impulsivity is a relevant construct for explaining both normal individual differences in personality and more extreme personality disorder, and is often investigated within clinical populations. This study aims to explore the college students impulsivity patterns and to investigate the association across levels of impulsivity with trauma exposure and PTSD development in a non-clinical population. A one-phase census survey of seven college institutions assessed 2213 students in three metropolitan regions of Northeastern Brazil. All subjects anonymously completed a self-applied protocol consisting of: a socio-demographic questionnaire, Trauma History Questionnaire (THQ), PTSD Checklist (PCL-C), and Barratt Impulsiveness Scale (BIS-11). The median for frequency of trauma exposure was 4 events for people with low and normal impulsivity, and 6 for highly impulsive ones. Individuals with higher impulsivity presented earlier exposition than non-impulsive ones, and worst outcome: 12.4% with PTSD, against 8.4% and 2.3% (normal and low impulsivity). Of the three factors of impulsivity, the Attentional factor conferred the strongest association with PTSD development. Results suggest that impulsivity is also a relevant trait in a non-clinical population and is associated with trauma exposure and PTSD. Strategies to promote mental health in adolescents may be pertinent, especially with the aim of managing impulsivity.

Hospitalizations of children due to primary health care sensitive conditions in Pernambuco State, Northeast Brazil

Admissions due to primary health care sensitive conditions from 1999 to 2009 among children < 5 years old were analyzed for municipalities in Pernambuco State, Brazil. Using data from the Brazilian Unified National Health Systems Hospital Information System, a negative binomial regression was applied to estimate rate ratio (RR) and 95%CI for the effect on primary health care sensitive condition rates (admissions/10,000 inhabitants) of the Family Health Program (FHP) coverage (%), some demographic variables and living conditions. Hospitalizations due to primary health care sensitive conditions represented 44.1% of 861,628 admissions and the rate declined from 557.6 to 318.9 (-42.8%), a reduction three times greater than the rate due to all other causes. Increased FHP coverage was protective against primary health care sensitive conditions (RR = 0.94; 95%CI: 0.89-0.99). A decline in hospitalizations due to primary health care sensitive conditions indicated improvements in health status and may be associated with the consolidation of primary health care. Studies on access and quality of primary health care in relation to child morbidity and hospitalizations are needed.

Padrões alimentares de crianças menores de cinco anos de idade residentes na capital e em municípios da Bahia, Brasil, 1996 e 1999/2000

This cross-sectional study included 3,817 preschool children, of whom 1,770 in Salvador, Bahia State, Brazil, and 2,047 in urban and rural areas from nine other municipalities (counties) in the same State. The study used 24-hour recall and principal components analysis to identify and compare dietary patterns. The sample was stratified by age and area. In the first six months of life, breast milk composed the second and third patterns, with positive loadings for children in all 10 municipalities. For children under 17 months of age, pattern 1 was characterized by cows milk, flour, and sugar, except in rural areas. Pattern 2 was similar for children aged 6-17 months and consisted of bread/cookies, rice, beans, and meat. For children 18-23 months of age in urban areas, pattern 1 showed negative loadings for sugar, cows milk, and flour. In children over 24 months of age, fruits were not part of the first pattern. The study showed low consumption of milk and low variety of fruits and vegetables. This food consumption profile indicates the need for early interventions to promote healthy eating habits.Estudo transversal com 3.817 pre-escolares, 1.770 residentes em Salvador, Bahia, Brasil, e 2.047 nas areas urbana e rural de 10 municipios baianos. Utilizou-se recordatorio de 24 horas (R24h) e empregou-se analise fatorial por componentes principais com objetivo de identificar e comparar os principais padroes alimentares dessas criancas. Estratificou-se a amostra por idade e area. Antes dos seis meses de vida o leite materno compos o 2o e 3o padroes com carga positiva para criancas dos dez municipios. Para menores de 17 meses, o padrao 1 foi caracterizado por leite de vaca, farinhas e acucares. Em areas urbanas, pao/biscoito, arroz, feijao e carne integraram o padrao 2 aos 6-17 meses. Aos 18-23 meses, o padrao 1 apresentou carga negativa para acucares, leite de vaca e farinhas, exceto na area rural. Frutas nao fizeram parte do padrao 1 no grupo de 24 meses e mais. Observou-se baixo consumo de leite materno e pouca variacao de frutas e legumes a partir dos seis meses. Tal perfil de consumo alimentar indica a necessidade de intervencoes cada vez mais precoces para promocao de habitos alimentares saudaveis.

Dietary patterns of children under five years of age living in the State capital and other counties of Bahia State, Brazil, 1996 and 1999-2000

This cross-sectional study included 3,817 preschool children, of whom 1,770 in Salvador, Bahia State, Brazil, and 2,047 in urban and rural areas from nine other municipalities (counties) in the same State. The study used 24-hour recall and principal components analysis to identify and compare dietary patterns. The sample was stratified by age and area. In the first six months of life, breast milk composed the second and third patterns, with positive loadings for children in all 10 municipalities. For children under 17 months of age, pattern 1 was characterized by cows milk, flour, and sugar, except in rural areas. Pattern 2 was similar for children aged 6-17 months and consisted of bread/cookies, rice, beans, and meat. For children 18-23 months of age in urban areas, pattern 1 showed negative loadings for sugar, cows milk, and flour. In children over 24 months of age, fruits were not part of the first pattern. The study showed low consumption of milk and low variety of fruits and vegetables. This food consumption profile indicates the need for early interventions to promote healthy eating habits.Estudo transversal com 3.817 pre-escolares, 1.770 residentes em Salvador, Bahia, Brasil, e 2.047 nas areas urbana e rural de 10 municipios baianos. Utilizou-se recordatorio de 24 horas (R24h) e empregou-se analise fatorial por componentes principais com objetivo de identificar e comparar os principais padroes alimentares dessas criancas. Estratificou-se a amostra por idade e area. Antes dos seis meses de vida o leite materno compos o 2o e 3o padroes com carga positiva para criancas dos dez municipios. Para menores de 17 meses, o padrao 1 foi caracterizado por leite de vaca, farinhas e acucares. Em areas urbanas, pao/biscoito, arroz, feijao e carne integraram o padrao 2 aos 6-17 meses. Aos 18-23 meses, o padrao 1 apresentou carga negativa para acucares, leite de vaca e farinhas, exceto na area rural. Frutas nao fizeram parte do padrao 1 no grupo de 24 meses e mais. Observou-se baixo consumo de leite materno e pouca variacao de frutas e legumes a partir dos seis meses. Tal perfil de consumo alimentar indica a necessidade de intervencoes cada vez mais precoces para promocao de habitos alimentares saudaveis.

Within- and between-group regression for improving the robustness of causal claims in cross-sectional analysis

BackgroundA major objective of environmental epidemiology is to elucidate exposure-health outcome associations. To increase the variance of observed exposure concentrations, researchers recruit individuals from different geographic areas. The common analytical approach uses multilevel analysis to estimate individual-level associations adjusted for individual and area covariates. However, in cross-sectional data this approach does not differentiate between residual confounding at the individual level and at the area level. An approach allowing researchers to distinguish between within-group effects and between-group effects would improve the robustness of causal claims.MethodsWe applied an extended multilevel approach to a large cross-sectional study aimed to elucidate the hypothesized link between drinking water pollution from perfluoroctanoic acid (PFOA) and plasma levels of C-reactive protein (CRP) or lymphocyte counts. Using within- and between-group regression of the individual PFOA serum concentrations, we partitioned the total effect into a within- and between-group effect by including the aggregated group average of the individual exposure concentrations as an additional predictor variable.ResultsFor both biomarkers, we observed a strong overall association with PFOA blood levels. However, for lymphocyte counts the extended multilevel approach revealed the absence of a between-group effect, suggesting that most of the observed total effect was due to individual level confounding. In contrast, for CRP we found consistent between- and within-group effects, which corroborates the causal claim for the association between PFOA blood levels and CRP.ConclusionBetween- and within-group regression modelling augments cross-sectional analysis of epidemiological data by supporting the unmasking of non-causal associations arising from hidden confounding at different levels. In the application example presented in this paper, the approach suggested individual confounding as a probable explanation for the first observed association and strengthened the robustness of the causal claim for the second one.